Complication rates of percutaneous brachial artery puncture: effect of live ultrasound guidance

Purpose

The current literature on the use of brachial artery access is controversial. Some studies found increased puncture site complications. Others found no higher complication rates than in patients with femoral or radial access. The purpose of this study was to determine the impact of ultrasound (US)-guidance on access site complications.

Materials and methods

This is a single-center retrospective study of all consecutive patients with brachial arterial access for interventional procedures. Complications were classified into minor complications (conservative treatment only) and major complications (requiring surgical intervention). The brachial artery was cannulated in the antecubital fossa under US-guidance. After the intervention, manual compression or closure devices, both followed by a compression bandage for 3 h, either achieved hemostasis.

Results

Seventy-five procedures in seventy-one patients were performed in the study period using brachial access. Access was successful in all cases (100%). Procedures in different vascular territories were performed: neurovascular (10/13.5%), upper extremity (32/43.2%), visceral (20/27.0%), and lower extremity (12/16.3%). Sheath size ranged from 3.2F to 8F (mean: 5F). Closure devices were used in 17 cases (22.7%). In total, six complications were observed (8.0%), four minor complications (5.3%, mostly puncture site hematomas), and two major complications, that needed surgical treatment (2.7%). No brachial artery thrombosis or upper extremity ischemia occurred.

Conclusion

Exclusive use of US-guidance resulted in a low risk of brachial artery access site complications in our study compared to the literature. US-guidance has been proven to reduce the risk of access site complications in several studies in femoral access. In addition, brachial artery access yields a high technical success rate and requires no additional injection of spasmolytic medication. Sheath size was the single significant predictor for complications.

[Clinical experience in the diagnosis and treatment of kidney trauma]

BACKGROUND

Kidney trauma belongs to the rarely arising urological illnesses. In recent years guidelines for the treatment of urological injuries have been compiled by the Société Internationale d'Urologie (SIU) and the European Association of Urology (EAU). In the current literature increasingly more meaning is granted to a conservative in relation to a surgical therapy procedure, also with grade 4 and 5 kidney injuries.

PATIENTS

From 2002 to 2009, 83 patients with kidney injuries were treated in our hospital. There were 56 patients with grade 1 and grade 2 injuries, 12 patients with grade 3 and grade 4 injuries, and in addition, a total of 15 patients with a grade 5 injury.

RESULTS

In 75% of the cases a conservative procedure could be arranged depending on the further clinical course. In 25% of the cases, however, relative and/or absolute indications for operative intervention stood in the foreground, so that this group had an exploratory laparotomy. In 7 cases total nephrectomy had to be performed; however, in 11 cases organ-preserving surgery was possible.

Increase of intracellular Ca2+ by P2X and P2Y receptor-subtypes in cultured cortical astroglia of the rat

Astrocytes express purinergic receptors that are involved in glial-neuronal cell communication. Experiments were conducted to characterize the expression of functional P2X/P2Y nucleotide receptors in glial cells of mixed cortical cell cultures of the rat. The vast majority of these cells was immunopositive for glial fibrillary acidic protein (GFAP) and was considered therefore astrocyte-like; for the sake of simplicity they were termed "astroglia" throughout. Astroglia expressed predominantly P2X(4,6,7) as well as P2Y(1,2) receptor-subtypes. Less intensive immunostaining was also found for P2X(5) and P2Y(4,6,13,14) receptors. Pressure application of ATP and a range of agonists selective for certain P2X or P2Y receptor-subtypes caused a concentration-dependent increase of intracellular Ca(2+) ([Ca(2+)](i)). Of the agonists tested, only the P2X(1,3) receptor-selective alpha,beta-methylene ATP was ineffective. Experiments with Ca(2+)-free solution and cyclopiazonic acid, an inhibitor of the endoplasmic Ca(2+)-ATPase, indicated that the [Ca(2+)](i) response to most nucleotides, except for ATP and 2',3'-O-(benzoyl-4-benzoyl)-ATP, was due primarily to the release of Ca(2+) from intracellular stores. A Gprotein-mediated release of Ca(2+) is the typical signaling mechanism of various P2Y receptor-subtypes, whose presence was confirmed also by cross-desensitization experiments and by using selective antagonists. Thus, our results provide direct evidence that astroglia in mixed cortical cell cultures express functional P2Y (P2Y(1,2,6,14) and probably also P2Y(4)) receptors. Several unidentified P2X receptors, including P2X(7), may also be present, although they appear to only moderately participate in the regulation of [Ca(2+)](i). The rise of [Ca(2+)](i) is due in this case to the transmembrane flux of Ca(2+) via the P2X receptor-channel. In conclusion, P2Y rather than P2X receptor-subtypes are involved in modulating [Ca(2+)](i) of cultured astroglia and thereby may play an important role in cell-to-cell signaling.

Study of gelatin supplemented diet on amino acid homeostasis in the horse

REASONS FOR PERFORMING STUDY

Gelatin supplementation is a common measure in an attempt to assist cartilage repair, but little scientific evidence exists to support its efficacy.

OBJECTIVES

To investigate the effects of gelatin administration on post prandial homeostasis.

METHODS

Twelve Standardbred horses (mean 404 kg bwt) were fed a hay-concentrate diet supplemented by soy bean meal and oil (control [C], n = 6) or with the addition of 60 g gelatin/day (G, n = 6). The horses were trained by an alternate order of interval and prolonged exercise every second day. The velocities of the treadmill corresponding to 2 and 10 mmol lactate/l blood were derived from lactate curves during a standardised exercise test at the start and middle of the 64 day training period. Blood samples for amino acid analysis were obtained weekly at rest (2 h post prandial). In the second part of the training period, a post prandial sampling was conducted on a day without exercise (prior feeding up to 8 h post prandial). Plasma free amino acids (AA) were determined by HPLC.

RESULTS

The change from pre- to the training diet induced an increase in many AA during the total training period. At rest free glycine and proline in blood increased with gelatin supplementation during 7 days after the start of supplementation. The AA in plasma showed a post prandial curve with peak concentrations 2-3 h after feeding. Significant post prandial effects of gelatin intake were detectable for glycine, proline and arginine.

CONCLUSIONS

The AA from gelatin are absorbed quickly and become available for AA metabolism.

POTENTIAL RELEVANCE

It is evident that in the horse, gelatin influences the homeostasis of those amino acids required for cartilage synthesis. Further research is needed to elucidate the utilisation of those amino acids for the prevention or repair of cartilage damage.

Ventilator-induced lung injury upregulates and activates gelatinases and EMMPRIN: attenuation by the synthetic matrix metalloproteinase inhibitor, Prinomastat (AG3340)

Mechanical ventilation has become an indispensable therapeutic modality for patients with respiratory failure. However, a serious potential complication of MV is the newly recognized ventilator-induced acute lung injury. There is strong evidence suggesting that matrix metalloproteinases (MMPs) play an important role in the development of acute lung injury. Another factor to be considered is extracellular matrix metalloproteinase inducer (EMMPRIN). EMMPRIN is responsible for inducing fibroblasts to produce/secrete MMPs. In this report we sought to determine: (1) the role played by MMPs and EMMPRIN in the development of ventilator-induced lung injury (VILI) in an in vivo rat model of high volume ventilation; and (2) whether the synthetic MMP inhibitor Prinomastat (AG3340) could prevent this type of lung injury. We have demonstrated that high volume ventilation caused acute lung injury. This was accompanied by an upregulation of gelatinase A, gelatinase B, MT1-MMP, and EMMPRIN mRNA demonstrated by in situ hybridization. Pretreatment with the MMP inhibitor Prinomastat attenuated the lung injury caused by high volume ventilation. Our results suggest that MMPs play an important role in the development of VILI in rat lungs and that the MMP-inhibitor Prinomastat is effective in attenuating this type of lung injury.

Evaluation of intraocular pharmacokinetics and toxicity of prinomastat (AG3340) in the rabbit

To determine the ocular pharmacokinetics, physiological and histological effects of prinomastat (a matrix metalloprotease inhibitor), a total of seventy-seven eyes of New Zealand White rabbits received intravitreous and subtenon injections of prinomastat or of acidified water vehicle as control, Doses of 0.5 mg in 0.05 mL of prinomastat or acidified water were used for intravitreal injection. For the subtenon injections, doses of 5 mg prinomastat in 0.5 mL of acidified water were administered in the superotemporal quadrant. Intraocular pharmacokinetics were determined by analyzing vitreous samples at different postinjection time points using Liquid Chromatography-Mass Spectroscopy/Mass Spectroscopy (LC-MS/MS). The toxicity was evaluated by biomicroscopy, electroretinography (ERG), pneumatonometry, and histology. No toxicity was found with either administration method. At day 14 after intravitreal injection, levels of prinomastat in the vitreous and choroid were 1.4 ng/mg and 7.8 ng/mg, respectively. The retinal levels of prinomastat were 22 ng/mg at 24 hr and dropped below 1 ng/mg at 48 hr. Prinomastat remained well above minimum effective concentration in the choroid for at least four weeks after a single intravitreal injection, suggesting that local intravitreal injection may have potential in treating choroidal neovascularization.

The effect of prinomastat (AG3340), a synthetic inhibitor of matrix metalloproteinases, on posttraumatic proliferative vitreoretinopathy

In a search for a pharmacologic adjuvant in the management of posttraumatic proliferative vitreoretinopathy (PVR), we investigated the effect of intravitreal injection of prinomastat (AG3340) on an experimental model. Posterior penetrating eye trauma was created in one eye each of 24 New Zealand white rabbits. One week after the surgery, all rabbits were randomized (1:1) to receive 0.5 mg prinomastat or the vehicle of the drug intravitreally every week for 6 weeks. The degree of PVR for each hemiretina was scored, and the two scores were summed to obtain a total eye score. The mean total eye score was 3.58 in the treatment group and 5.75 in the control group (p = 0.0307). The numbers of eyes with tractional retinal detachment in the prinomastat-treated (n = 12) and control (n = 12) groups were 3 and 9, respectively (p = 0.0391). These results suggest that intravitreally administered prinomastat has an inhibitory effect on posttraumatic PVR.

The effect of prinomastat (AG3340), a potent inhibitor of matrix metalloproteinases, on a subacute model of proliferative vitreoretinopathy

PURPOSE

To determine the efficacy of prinomastat (AG3340), a synthetic inhibitor of matrix metalloproteinase, in the treatment of experimental proliferative vitreoretinopathy (PVR) induced by intravitreal dispase injection.

METHODS

One eye each of 53 New Zealand white rabbits was injected in the vitreous cavity with 0.07 unit of dispase to induce PVR. One week after PVR induction, 53 rabbits were randomized (27:26) to receive 0.5 mg prinomastat or the vehicle of the drug (acidified water) intravitreally every two weeks. The scores of PVR severity (scale of 1-5) were graded to compare the prinomastat-treated animals with the control group.

RESULTS

The average PVR scores in the treatment and control groups were 2.62 and 3.57 respectively (p = 0.038; Wilcoxon rank sum). Clinically significant PVR with retinal detachment (PVR > or = grade 3) developed in 76% of rabbits in the control group versus 51% of rabbits treated with prinomastat.

CONCLUSIONS

Intravitreally administered prinomastat decreased development of PVR in an experimental model which made use of dispase to induce PVR.

Antitumor efficacy of AG3340 associated with maintenance of minimum effective plasma concentrations and not total daily dose, exposure or peak plasma concentrations

Oral administration of AG3340, a novel metalloprotease (MMP) inhibitor, suppresses the growth of human colon adenocarcinoma (COLO-320DM) tumors in vivo (Proc Am Assoc Cancer Res 39: 2059, 1998). In this report, we tested the hypothesis that the growth inhibition of these tumors is associated with maintaining minimum effective plasma concentrations of AG3340. Nude mice were given a total oral daily dose of 25 or 200 mg/kg; 6.25 mg/kg was given four times per day (QID) (25 mg/kg/day), and 100 mg/kg was given in two daily doses (BID) (200 mg/kg/day). Peak plasma concentrations (Cmax) of 83 +/- 43 (mean +/- SD) and 1998 +/- 642 ng/ml were detected 30 min after a single dose with 6.25 mg/kg and 100 mg/kg AG3340, respectively. AUC(0-24 h) values estimated from dosing with 25 and 200 mg/kg/day AG3340 were 672 and 10882 ng*h/ml, respectively. Importantly, both regimen inhibited tumor growth equivalently (74 to 82%). Efficacy was also compared at a total daily dose of 25 mg/kg by giving AG3340: QID (6.25 mg/kg per dose), BID (12.5 mg/kg per dose), and once daily (25 mg/kg per dose). The Cmax of these regimens was 83 +/- 43, 287 +/- 175 and 462 +/- 495 ng/ml, respectively. AG3340 did not inhibit tumor growth with the latter two regimens. The efficacy of 6.25 mg/kg QID (25 mg/kg/day) was superior to the efficacy of 25 mg/kg BID (50 mg/kg/day), substantiating the independence of efficacy from the total daily dose and Cmax. Expectedly, peak to trough fluctuations were significantly smaller with the QID regimen than with BID and QD dosing. After 24 h, the trough was greater than 1 ng/ml with QID dosing but was less than 1 ng/ml after QD and BID dosing. These results suggest that the antitumor efficacy of AG3340 was associated with maintaining minimum effective plasma concentrations of AG3340 and demonstrate that the antitumor efficacy of AG3340 was independent of the total daily dose, peak plasma concentration, and drug exposure in this tumor model.

Marked antiangiogenic and antitumor efficacy of AG3340 in chemoresistant human non-small cell lung cancer tumors: single agent and combination chemotherapy studies

Effective therapy is needed to improve the survival of patients with advanced lung cancers. We studied the effects of a selective metalloprotease inhibitor, AG3340, on chemoresistant human non-small cell lung cancer tumors (line MV522) in vivo. Mice bearing s.c. tumors were given twice-daily oral doses of AG3340. As a single agent, AG3340 inhibited angiogenesis (up to 77%) and tumor growth (up to 65%) in a dose-dependent manner at well-tolerated daily doses up to 400 mg/kg/day and induced significant tumor necrosis. In contrast, tumors were relatively insensitive to carboplatin with approximately 25% growth inhibition observed at a maximum tolerated dose of approximately 30 mg/kg/week (given i.p., twice weekly). Carboplatin inhibited tumor growth markedly only at toxic doses, demonstrating a superior therapeutic index of AG3340 to carboplatin in this tumor model. A suboptimal dose of AG3340, when used in combination with an ineffective maximum tolerated dose of carboplatin, resulted in greater tumor growth inhibitions than those produced by either agent alone. Similarly, growth inhibition was enhanced when AG3340 was used in combination with paclitaxel. Cotreatment with carboplatin did not alter AG3340 plasma concentrations achieved acutely after oral dosing. These data demonstrate an antiangiogenic and antitumor effect of AG3340 when used as a single agent and enhanced growth inhibitions when AG3340 is used in combination with cytotoxic agents. These data suggest that treatment with this novel matrix metalloprotease inhibitor may be beneficial in advanced lung cancers and other chemoresistant malignancies.

Broad antitumor and antiangiogenic activities of AG3340, a potent and selective MMP inhibitor undergoing advanced oncology clinical trials

We studied AG3340, a potent metalloproteinase (MMP) inhibitor with pM affinities for inhibiting gelatinases (MMP-2 and -9), MT-MMP-1 (MMP-14), and collagenase-3 (MMP-13) in many tumor models. AG3340 produced dose-dependent pharmacokinetics and was well tolerated after intraperitoneal (i.p.) and oral dosing in mice. Across human tumor models, AG3340 produced profound tumor growth delays when dosing began early or late after tumor implantation, although all established tumor types did not respond to AG3340. A dose-response relationship was explored in three models: COLO-320DM colon, MV522 lung, and MDA-MB-435 breast. Dose-dependent inhibitions of tumor growth (over 12.5-200 mg/kg given twice daily, b.i.d.) were observed in the colon and lung models; and in a third (breast), maximal inhibitions were produced by the lowest dose of AG3340 (50 mg/kg, b.i.d.) that was tested. In another model, AG3340 (100 mg/kg, once daily, i.p.) markedly inhibited U87 glioma growth and increased animal survival. AG3340 also inhibited tumor growth and increased the survival of nude mice bearing androgen-independent PC-3 prostatic tumors. In a sixth model, KKLS gastric, AG3340 did not inhibit tumor growth but potentiated the efficacy of Taxol. Importantly, AG3340 markedly decreased tumor angiogenesis (as assessed by CD-31 staining) and cell proliferation (as assessed by bromodeoxyuridine incorporation), and increased tumor necrosis and apoptosis (as assessed by hematoxylin and eosin and TUNEL staining). These effects were model dependent, but angiogenesis was commonly inhibited. AG3340 had a superior therapeutic index to the cytotoxic agents, carboplatin and Taxol, in the MV522 lung cancer model. In combination, AG3340 enhanced the efficacy of these cytotoxic agents without altering drug tolerance. Additionally, AG3340 decreased the number of murine melanoma (B16-F10) lesions arising in the lung in an intravenous metastasis model when given in combination with carboplatin or Taxol. These studies directly support the use of AG3340 in front-line combination chemotherapy in ongoing clinical trials in patients with advanced malignancies of the lung and prostate.

Marked inhibition of tumor growth in a malignant glioma tumor model by a novel synthetic matrix metalloproteinase inhibitor AG3340

Synthetic matrix metalloproteinase (MMP) inhibitors have activity against a variety of tumors in preclinical models but have not been studied in gliomas. We determined the effect of AG3340, a novel synthetic MMP inhibitor with Ki values against gelatinases in the low picomolar range, on the growth of a human malignant glioma cell line (U87) in SCID-NOD mice. Mice were injected s.c. with U87 cells. Tumors were allowed to grow to a size of approximately 0.5 x 0.5 cm (after about 3 weeks), and the mice were randomized to receive either: (a) 100 mg/kg AG3340 in vehicle; or (b) vehicle control (0.5% carboxymethyl cellulose, 0.1% pluronic F68), both given daily i.p. Tumor area was measured twice weekly, and animals were sacrificed when moribund, or earlier if premorbid histology was examined. In vivo inhibition of tumor growth was profound, with AG3340 decreasing tumor size by 78% compared with controls after 31 days (when controls were sacrificed; P < 0.01, Wilcoxon test). Control animals survived 31 days after the i.p. injections began, and AG3340 mice survived 71 days, representing a >2-fold increase in survival associated with tumor growth delay. Histological examination found that AG3340-treated tumors were smaller, had lower rates of proliferation, and significantly less invasion than control-treated tumors. Hepatic or pulmonary metastases were not seen in either group. In a separate experiment, the tumors were smaller and sampled after a shorter duration of treatment; the changes in proliferation were more marked and occurred earlier than differences in tumor invasion between the two groups. Furthermore, in vitro cell growth was not inhibited at AG3340 concentrations of <1 mM. AG3340 plasma concentrations in vivo, 1 h after administration, ranged from 67 to 365 nM. Thus, AG3340 produced a profound inhibition of glioma tumor growth and invasion. AG3340 markedly increased survival in this in vivo glioma model. Treatment with AG3340 may be potentially useful in patients with malignant gliomas.

The high-resolution structure of DNA-binding protein HU from Bacillus stearothermophilus

Protein HU is a ubiquitous prokaryotic protein which controls the architecture of genomic DNA. It binds DNA non-specifically and promotes the bending and supercoiling of the double helical structure. HU is involved in many DNA-associated cellular processes, including replication, transcription and the packaging of DNA into chromosome-like structures. Originally determined at medium resolution, the crystal structure of HU has now been refined at 2.0 A resolution. The high-resolution structure shows that the dimeric molecule is essentially a compact platform for two flexible and basic arms which wrap around the DNA molecule. To maximize the protein's stability, non-secondary structural regions are reduced to a minimum, there is an extensive aromatic hydrophobic core and several salt bridges and hydrogen-bonded water molecules knit together crucial regions. Based on the original medium-resolution structure of HU, several proposals were made concerning the structural basis of HU's ability to bind, bend and supercoil DNA. Each of these proposals is fully supported by the high-resolution structure. Most notably, the surfaces of the molecule which appear to mediate protein-DNA and protein-protein interactions have the ideal shapes and physicochemical properties to perform these functions.

Crystal structure of the kinase domain of human vascular endothelial growth factor receptor 2: a key enzyme in angiogenesis

BACKGROUND

Angiogenesis is involved in tumor growth, macular degeneration, retinopathy and other diseases. Vascular endothelial growth factor (VEGF) stimulates angiogenesis by binding to specific receptors (VEGFRs) on the surface of vascular endothelial cells. VEGFRs are receptor tyrosine kinases that, like the platelet-derived growth factor receptors (PDGFRs), contain a large insert within the kinase domain.

RESULTS

We report here the generation, kinetic characterization, and 2.4 A crystal structure of the catalytic kinase domain of VEGF receptor 2 (VEGFR2). This protein construct, which lacks 50 central residues of the 68-residue kinase insert domain (KID), has comparable kinase activity to constructs containing the entire KID. The crystal structure, determined in an unliganded phosphorylated state, reveals an overall fold and catalytic residue positions similar to those observed in other tyrosine-kinase structures. The kinase activation loop, autophosphorylated on Y1059 prior to crystallization, is mostly disordered; however, a portion of it occupies a position inhibitory to substrate binding. The ends of the KID form a beta-like structure, not observed in other known tyrosine kinase structures, that packs near to the kinase C terminus.

CONCLUSIONS

The majority of the VEGFR2 KID residues are not necessary for kinase activity. The unique structure observed for the ends of the KID may also occur in other PDGFR family members and may serve to properly orient the KID for signal transduction. This VEGFR2 kinase structure provides a target for design of selective anti-angiogenic therapeutic agents.

Characterization and kinetic mechanism of catalytic domain of human vascular endothelial growth factor receptor-2 tyrosine kinase (VEGFR2 TK), a key enzyme in angiogenesis

Vascular endothelial growth factor (VEGF) is a dimeric protein which induces formation of new blood vessels (angiogenesis) through binding to VEGF-receptor-2 tyrosine kinase (VEGFR2 TK) or KDR (kinase insert domain-containing receptor) on the surface of endothelial cells. Angiogenesis has been shown to be essential for malignancy of tumors; therefore, VEGFR2 TK is a potential therapeutic target for the treatment of cancer. Sequence homology studies indicate that VEGFR2 TK contains three domains: extracellular (ligand-binding domain), transmembrane, and intracellular (catalytic domain). In this work, the catalytic domain of VEGFR2 TK was cloned and expressed in a soluble active form using a baculovirus expression system. In the absence of ligand, the enzyme is shown to catalyze its autophosphorylation in a time-dependent and enzyme-concentration-dependent manner, consistent with a trans mechanism for this reaction. Mass spectrometry analysis revealed incorporation of 5.5 +/- 0.5 mol of phosphate/mole of enzyme (monomer). In addition, the enzyme was shown to catalyze phosphorylation of a synthetic peptide, poly(E4Y). Using poly(E4Y) as substrate, the kinetic constants of both native and phosphorylated enzyme were determined. Enzyme phosphorylation increased catalytic efficiency of the enzyme by at least an order of magnitude. Furthermore, the enzyme was shown to catalyze the reverse reaction using phospho-poly(E4Y) as substrate. Cd2+ was found to be an inhibitor of the enzyme. Kinetic studies revealed that inhibition by Cd2+ was competitive with respect to Mg2+ and noncompetitive with respect to MgATP. These results indicate that Cd2+ competes for a second metal-binding site. Therefore, the reaction catalyzed by this enzyme was treated as a terreactant system. The kinetic mechanism of VEGFR2 TK was elucidated through the use of steady-state kinetic studies. According to these studies, the enzyme binds Mg2+ and MgATP in a random fashion followed by ordered addition of the peptide substrate. The release of product is also ordered, with MgADP being released last. The order of substrate binding was confirmed by using AMP-PCP, a dead-end inhibitor.

Viracept (nelfinavir mesylate, AG1343): a potent, orally bioavailable inhibitor of HIV-1 protease

Using a combination of iterative structure-based design and an analysis of oral pharmacokinetics and antiviral activity, AG1343 (Viracept, nelfinavir mesylate), a nonpeptidic inhibitor of HIV-1 protease, was identified. AG1343 is a potent enzyme inhibitor (Ki = 2 nM) and antiviral agent (HIV-1 ED50 = 14 nM). An X-ray cocrystal structure of the enzyme-AG1343 complex reveals how the novel thiophenyl ether and phenol-amide substituents of the inhibitor interact with the S1 and S2 subsites of HIV-1 protease, respectively. In vivo studies indicate that AG1343 is well absorbed orally in a variety of species and possesses favorable pharmacokinetic properties in humans. AG1343 (Viracept) has recently been approved for marketing for the treatment of AIDS.

Rodent pharmacokinetic and anti-tumor efficacy studies with a series of synthetic inhibitors of matrix metalloproteinases

Matrix metalloproteinases are a family of zinc-containing proteases that degrade extracellular matrix and basement membranes. These enzymes are thought to play a role in processes essential for tumor growth, invasion, and metastasis. Here we report pharmacokinetic and anti-tumor efficacy studies with a series of structurally related inhibitors of these enzymes that were synthesized at Agouron Pharmaceuticals using protein structure based drug design. The compounds studied were AG3287, AG3293, AG3294, AG3296, AG3319, and AG3340. Rat oral bioavailability ranged from 15 to 68%. Despite similar profiles of enzyme inhibition across the family of enzymes, and similar pharmacokinetics following i.p. administration to mice, efficacy against the Lewis lung carcinoma murine model varied from tumor growth enhancement, to significant reductions in the size of primary tumors and the number of lung metastases. AG3340 was the most efficacious compound against the Lewis lung carcinoma model, resulting in the complete cessation of primary tumor growth throughout the experiment in 4/6 mice treated with daily i.p. injections at a dose of 50 mg/kg. This treatment inhibited the formation of lung metastases greater than 5 mm in diameter by 90%.

Structure-based design and synthesis of substituted 2-butanols as nonpeptidic inhibitors of HIV protease: secondary amide series

The design, synthesis, and crystallographic analysis of protein-inhibitor complexes is described for a novel series of nonpeptidic HIV protease (HIV Pr)inhibitors. Beginning with a cocrystal structure of a Phe-Pro peptidomimetic bound to the HIV Pr, design was initiated that resulted in the substituted 2-butanol compound 8 as the lead compound (Ki = 24.5 microM, racemic mixture). Modifications on the initial compound were then made on the basis of its cocrystal structure with HIV Pr and inhibition data, resulting in compounds with enhanced potency against the enzyme (compound 18, Ki = 0.48 microM). These inhibitors were found to bind to the enzyme essentially as predicted on the basis of the original design hypothesis. Stereospecific synthesis of individual enantiomers confirmed the prediction of a binding preference for the S alcohol stereochemistry. Modest antiviral activity was demonstrated for several of the more potent HIV Pr inhibitors in a HIV-1 infected CEM-SS cell line.

Bis tertiary amide inhibitors of the HIV-1 protease generated via protein structure-based iterative design

A series of potent nonpeptide inhibitors of the HIV protease have been identified. Using the structure of compound 3 bound to the HIV protease, bis tertiary amide inhibitor 9 was designed and prepared. Compound 9 was found to be about 17 times more potent than 3, and the structure of the protein-ligand complex of 9 revealed the inhibitor binds in an inverted binding mode relative to 3. Examination of the protein-ligand complex of 9 suggested several modifications in the P1 and P1' pockets. Through these modifications it was possible to improve the activity of the inhibitors another 100-fold, highlighting the utility of crystallographic feedback in inhibitor design. These compounds were found to have good antiviral activity in cell culture, were selective for the HIV protease, and were orally available in three animal models.

Structure-based design of lipophilic quinazoline inhibitors of thymidylate synthase

To develop novel lipophilic thymidylate synthase (TS) inhibitors, the X-ray structure of Escherichia coli TS in ternary complex with FdUMP and the inhibitor 10-propargyl-5,8-dideazafolic acid (CB3717) was used as a basis for structure-based design. A total of 31 novel lipophilic TS inhibitors, lacking a glutamate residue, were synthesized; 26 of them had in common a N-((3,4-dihydro-2-methyl-6-quinazolinyl)methyl)-N-prop-2-ynylaniline+ ++ structure in which the aniline was appropriately substituted with simple lipophilic substituents either in position 3 or 4, or in both. Compounds were tested for their inhibition of E. coli TS and human TS and also for their inhibition of the growth in tissue culture of a murine leukemia, a human leukemia, and a thymidine kinase-deficient human adenocarcinoma. The crystal structures of five inhibitors complexed with E. coli TS were determined. Five main conclusions are drawn from this study. (i) A 3-substituent such as CF(3), iodo, or ethynyl enhances binding by up to 1 order of magnitude and in the case of CF(3) was proven to fill a nearby pocket in the enzyme. (ii) A simple strongly electron-withdrawing substituent such as NO(2) or CF(3)SO(2) in the 4-position enhances binding by 2 orders of magnitude; it is hypothesized that the transannular dipole so induced interacts favorably with the protein. (iii) Attempts to combine the enhancements of i and ii in the same molecule were generally unsuccessful (iv) A 4-C(6)H(5)SO(2) substituent provided both electron withdrawal and a van der Waal's interaction of the phenyl group with a hydrophobic surface at the mouth of the active site. The inhibition (K(is) = 12 nM) of human TS by this compound, 7n, showed that C(6)H(5)SO(2) provided virtually as much binding affinity as the CO-glutamate which it had replaced. (v) The series of compounds were poorly water soluble, and also the potent TS inhibition shown by several of them did not translate into good cytotoxicity. Compounds with large cyclic groups linked to position 4 by an SO or SO(2) group did, however, have IC(50)'s in the range 1-5 microM. Of these, 4-(N-((3,4-dihydro-2-methyl-6-quinazolinyl)methyl)-N-prop-2-ynylamino )phenyl phenyl sulfone, 7n, had IC(50)'s of about 1 microM and was chosen for further elaboration.

Antiviral and resistance studies of AG1343, an orally bioavailable inhibitor of human immunodeficiency virus protease

AG1343 ([3S-(3R*,4aR*,8aR*,2'S*,3'S*)]-2-[2' hydroxy-3'-phenylthiomethyl-4'-aza-5'-oxo-5'-(2''-methyl-3''-hydro xy-phenyl) pentyl]-decahydroiso-quinoline-3-N-t-butylcarboxamide methanesulfonic acid) is a selective, nonpeptidic inhibitor of human immunodeficiency virus (HIV) protease (Ki = 2 nM) that was discovered by protein structure-based drug design methodologies. AG1343 was effective against the replication of several laboratory and clinical HIV type 1 (HIV-1) or HIV-2 isolates including pyridinone- and zidovudine-resistant strains, with 50% effective concentrations ranging from 9 to 60 nM. In reversibility studies, inhibition of gag (p55) proteolytic processing in HIV-1 particles from cells treated with AG1343 was maintained for up to 36 h after drug removal. The ability of virus to develop resistance to AG1343 was studied by serial passage of HIV-1 NL4.3 in the presence of increasing concentrations of drug. After 28 passages, a variant with a 30-fold reduction in susceptibility to AG1343 was isolated. Molecular analysis of the protease from this variant indicated a double change from a Met to Ile at residue 46 and an Ile to Val or Ala at residue 84 (M46I+I84V, A). Consistent with these findings, reductions in susceptibility were observed for recombinant viruses constructed to contain the single I84V change or the double M46I+I84V substitutions. Resistance, however, was not detected for recombinant viruses containing other key mutations in HIV-1 protease, including a Val to Ile change at residue 32 or a Val to Ala or Phe at residue 82. The potent anti-HIV activity of AG1343 against several isolates suggests that AG1343 should perform well during ongoing human phase II clinical trials.

Empirical free energy calculations of ligand-protein crystallographic complexes. I. Knowledge-based ligand-protein interaction potentials applied to the prediction of human immunodeficiency virus 1 protease binding affinity

The steadily increasing number of high-resolution human immunodeficiency virus (HIV) 1 protease complexes has been the impetus for the elaboration of knowledge-based mean field ligand-protein interaction potentials. These potentials have been linked with the hydrophobicity and conformational entropy scales developed originally to explain protein folding and stability. Empirical free energy calculations of a diverse set of HIV-1 protease crystallographic complexes have enabled a detailed analysis of binding thermodynamics. The thermodynamic consequences of conformational changes that HIV-1 protease undergoes upon binding to all inhibitors, and a substantial concomitant loss of conformational entropy by the part of HIV-1 protease that forms the ligand-protein interface, have been examined. The quantitative breakdown of the entropy-driven changes occurring during ligand-protein association, such as the hydrophobic contribution, the conformational entropy term and the entropy loss due to a reduction of rotational and translational degrees of freedom, of a system composed to ligand, protein and crystallographic water molecules at the ligand-protein interface has been carried out. The proposed approach provides reasonable estimates of distinctions in binding affinity and gives an insight into the nature of enthalpyentropy compensation factors detected in the binding process.

Protein structure-based design of potent orally bioavailable, nonpeptide inhibitors of human immunodeficiency virus protease

A class of potent nonpeptidic inhibitors of human immunodeficiency virus protease has been designed by using the three-dimensional structure of the enzyme as a guide. By employing iterative protein cocrystal structure analysis, design, and synthesis the binding affinity of the lead compound was incrementally improved by over four orders of magnitude. An inversion in inhibitor binding mode was observed crystallographically, providing information critical for subsequent design and highlighting the utility of structural feedback in inhibitor optimization. These inhibitors are selective for the viral protease enzyme, possess good antiviral activity, and are orally available in three species.

Purification of the Escherichia coli integration host factor (IHF) in one chromatographic step

The integration host factor (IHF) participates in a diverse array of DNA transactions such as replication, recombination and gene expression. We describe a fast and very efficient isolation procedure which yields highly purified IHF in one chromatographic step.

Crystal-structure-based design and synthesis of novel C-terminal inhibitors of HIV protease

The X-ray crystal-structure-based design, synthesis, computational evaluation, and activity of a novel class of HIV protease inhibitors are described. The initial lead compounds 2 and 3 were designed by modeling replacement groups for the C-terminal Val-Val-OCH3 of a known hydroxyethylene inhibitor into the active site of the reported crystal structure of HIV protease complexed with MVT-101. The lead compound 2 was found to be a modest inhibitor with a Ki = 1.67 microM. The X-ray crystal structure of compound 2 complexed with HIV protease was solved and used for subsequent design. The lead compound 3 was found to be a more potent inhibitor with Ki = 0.2 microM, and the structure of it complexed with HIV protease was also solved and used for subsequent design. Modification of both the C-terminus and N-terminus of indole 3 resulted in compounds with Ki = 30 nM. Using the crystal structure of compounds 2 and 3 with HIV protease as a starting point, the thermodynamic cycle perturbation molecular dynamics method was applied to a select group of compounds in order to test the accuracy of this type of computation within a series of closely related compounds.

Calculation of relative differences in the binding free energies of HIV1 protease inhibitors: a thermodynamic cycle perturbation approach

An iterative computer-assisted drug design (CADD) method that combines molecular mechanics, dynamics, thermodynamic cycle perturbation (TCP) calculations, molecular design, synthesis, and biochemical testing of peptidomimetic inhibitors and crystallographic structure determination of the protein-inhibitor complexes has been successfully applied to the design of novel inhibitors for the HIV1 protease. The first "designer" compound in this series (I) was designed by replacing the C-terminal Val-Val methyl ester of a known hydroxyethylene inhibitor with a diphenhydramine amide derivative in which two phenyl groups fill the p2' and p3' side-chain binding pockets in the HIV1 protease. Subsequent testing showed modest inhibition (Ki = 1.67 microM). Concurrently, molecular mechanics calculations on designed analogs indicated the feasibility of replacement of a phenyl ring with an indole ring (II). Synthesis and biochemical testing resulted in better inhibition potency for II. X-ray crystal structure determination of HIV1 protease complexed with I and II provided structural information for subsequent design and TCP calculations. A TCP protocol was established and validated for the mutation of I-->II. TCP results showed a net gain of 2.1 (+/- 0.9) kcal/mol in replacing II with I, which agreed with experimental result within an error margin of 0.8 kcal/mol. TCP calculations for six other mutations (I-->III, II-->III, IV, V, VI, and VII) were performed prior to synthesis and testing. These results allowed for the prioritization of design ideas for synthesis. In all cases where experimental results are available, TCP calculations showed good agreement. These results demonstrate that the TCP approach can be used with medicinal chemistry and crystallography for screening the proposed derivatives of a lead compound prior to synthesis, thus potentially reducing the time for the discovery of new drugs.

Crystallization and preliminary X-ray crystallographic analysis of Mirabilis antiviral protein

Mirabilis antiviral protein is a single-chain ribosome-inactivating protein purified from the tuberous root of Mirabilis jalapa L. We obtained several forms of crystals of the protein by the hanging drop vapor diffusion method, but most of these crystals were not suitable for X-ray crystallography. After refining the growth conditions, crystals of crystallographic quality were grown in 20-microliters droplets of an equi-volume mixture of 1.5% (w/v) protein solution and a reservoir solution containing 49 to 50% (w/v) ammonium sulfate and 50 mM-ammonium citrate (pH 5.4) at room temperature. Addition of 2 mM-adenine sulfate reduced twinning and "crystal shower". The resulting trigonal crystals diffract beyond 2.5 A resolution using a rotating anode X-ray generator. The space group was determined to be P3(1)21 or P3(2)21 (a = b = 103.9.A, c = 134.6 A, alpha = beta = 90 degrees, gamma = 120 degrees) based on their precession photography of h0l and hk0 zones. There seems to be three monomers in an asymmetric unit for VM = 2.51 A3/Da.

Crystal structure of Escherichia coli thymidylate synthase containing bound 5-fluoro-2'-deoxyuridylate and 10-propargyl-5,8-dideazafolate

The crystal structure of an Escherichia coli thymidylate synthase (TS) ternary complex containing 5-fluoro-2'-deoxyuridylate (FdUMP) and 10-propargyl-5,8-dideazafolate (PDDF) has been determined and refined at 2.3 A resolution. Each of the two chemically identical subunits folds into a three-layer domain anchored by a large six-stranded mixed beta-sheet. The backside of one sheet is juxtaposed against the corresponding face of the equivalent sheet in the second protomer creating a beta-sandwich. In contrast to other proteins of known structure in which aligned beta-sheets stack face to face with a counterclockwise rotation, sheets in the TS dimer are related by a clockwise twist. The substrate-binding pocket is a large funnel-shaped cleft extending some 25 A into the interior of each subunit and is surrounded by 30 amino acids, 28 from one subunit and two from the other. FdUMP binds at the bottom of this pocket covalently linked through C-6 to the sulfur of Cys146. Up-pointing faces of the pyrimidine and ribose rings are exposed to provide a complementary docking surface for the quinazoline ring of PDDF. The quinazoline inhibitor binds in a partially folded conformation with its p-aminobenzoyl glutamate tail exposed at the entrance to the active site cleft. Ternary complex formation is associated with a large conformational change involving four residues at the protein's carboxy terminus that close down on the distal side of the inhibitor's quinazoline ring, capping the active site and sequestering the bound ligands from bulk solvent.

High-level expression of self-processed HIV-1 protease in Escherichia coli using a synthetic gene

A synthetic gene coding for HIV-1 protease (PR) has been constructed and a system for its efficient expression in E. coli has been established: PR is synthesized as a fusion protein with E. coli dihydrofolate reductase under the control of a bacteriophage T7 promoter. The synthetic gene was constructed to enable rapid construction of defined mutants by restriction fragment replacement. A set of mutants has been constructed which may facilitate elucidation of the mechanism of PR self-cleavage from polyprotein precursors. We have demonstrated that the C-terminal residue (Phe99 in the native sequence) of the processing intermediate is absolutely required for subsequent cleavage at the N-terminal cleavage site. The potential structural role of this residue is discussed with reference to the recently published HIV-1 PR structure.

Stacked beta-bulges in thymidylate synthase account for a novel right-handed rotation between opposing beta-sheets

The beta-sandwich in thymidylate synthase comprises two six-stranded mixed beta-sheets, each contributed by one subunit of the dimeric molecule. In contrast to other proteins of known structure in which beta-sheets stack face to face, the central beta-sheets in the thymidylate synthase dimer are related by a right-handed rather than a left-handed twist. Using a highly refined model of an Escherichia coli thymidylate synthase ternary complex, we show that the individual beta-sheets in each subunit are severely distorted by an unusual series of stacked beta-bulges, which partitions each larger sheet into two smaller beta-sheets approximately orthogonal to one another. These stacked beta-bulges are locally stabilized by hydrogen bonding involving eight conserved residues. This extended structure anchors the phosphate of bound dUMP and controls the precise orientation of the catalytically essential active site cysteine. Stereochemical factors associated with the pronounced crease caused by these stacked bulges account for the right-handed twist of opposing beta-sheets.

Fluorescence studies of a single tyrosine in a type II DNA binding protein

We studied the fluorescence properties of a single tyrosine (Tyr94) located in the C-terminal tail of transcription factor 1 (TF1), a type II procaryotic DNA binding protein encoded by the Bacillus subtilis phage SPO1. The time-resolved fluorescence intensity of Tyr94 in free TF1 dimers decays as a single exponential, and this is consistent with a twofold symmetrical structure. The fluorescence is readily quenched by acrylamide, but it is less accessible to anionic quenchers (iodide and citrate), suggesting that the tyrosine is located on the protein surface in a negatively charged environment provided by neighboring Glu95 and Asp96 residues. TF1 dimers associate at moderate concentrations (greater than 0.02 mg/mL) as judged from concentration dependencies in the molar fluorescence intensity, the steady-state fluorescence polarization, and the bimolecular quenching constants. Nonspecific binding of TF1 to SPO1 and calf thymus (CT) DNA and various double-stranded polynucleotides quenches the Tyr94 fluorescence to varying extent. Fluorescence lifetimes of TF1 in the bound state correlate with spectral overlaps between TF1 emission and DNA absorption, demonstrating that excitation energy transfer to DNA bases contributes significantly to the observed quenching. From analysis of the observed quenching in the DNA complexes we conclude that Tyr94 is located within 10-14 A of the DNA helix axis and not in direct contact with the DNA bases. Equilibrium analyses based on fluorescence titrations show that the maximum binding density on DNA extrapolates to ca. 1 TF1 dimer/5 DNA base pairs. We find several differences in TF1 binding to SPO1 DNA, which contains hydroxymethyluracil instead of thymine, and CT DNA: (i) The tyrosine residue is less exposed to the solvent in the SPO1 DNA complex than in the CT DNA complex. (ii) D2O addition enhances the Tyr94 fluorescence when TF1 binds to SPO1 DNA but not when it binds to CT DNA. (iii) The TF1-SPO1 DNA complex is stable at higher NaC1 concentrations than is the TF1-CT DNA complex, and its formation involves the dissociation of more Na+ ions than does the TF1-CT DNA complex. On the basis of these observations and the fact that the Tyr94-containing tail of TF1 is essential for binding to SPO1 DNA, we discuss various models for the TF1-DNA complex.

Crystal structure of Escherichia coli thymidylate synthase with FdUMP and 10-propargyl-5,8-dideazafolate

The crystal structure of an E. coli TS ternary complex containing FdUMP and PDDF has been determined and refined at 2.3A resolution. Each of the two chemically identical subunits folds into a three-layer domain anchored by a large six-stranded mixed beta sheet. The backside of one sheet is juxtaposed against the corresponding face of the equivalent sheet in the second protomer creating a beta sandwich. In contrast to other proteins of known structure in which aligned beta sheets stack face to face with a counterclockwise rotation, sheets in the TS dimer are related by a clockwise twist. The substrate binding pocket is a large funnel-shaped cleft extending some 25A into the interior of each subunit and surrounded by 28 amino acids, 26 from one subunit and 2 from the other. FdUMP binds at the bottom of this pocket covalently linked through C6 to the sulfur of Cys-146. Up-pointing faces of the pyrimidine and ribose rings are exposed to provide a complementary docking surface for the quinazoline ring of PDDF. The quinazoline inhibitor binds in a partially folded conformation with its p-aminobenzoylglutamate tail exposed at the entrance to the active site cleft. Ternary complex formation is associated with a large conformational change involving 4 residues at the protein's carboxy-terminus that close down on the distal side of the inhibitor's quinazoline ring, capping the active site and sequestering the bound ligands from bulk solvent.

A protein structural motif that bends DNA

The prokaryotic protein HU, integration host factor (IHF) from Escherichia coli, and transcription factor 1 (TF1) from bacteriophage SPO1 are closely related molecules. Biochemical results suggest that the role of these proteins is to bind and bend DNA. From the high-resolution structure of HU, we propose a model for this interaction with DNA. Crucial amino acid differences between the proteins can be rationalized in terms of their different specific functions.

The integration host factor of Escherichia coli binds to multiple sites at plasmid R6K gamma origin and is essential for replication

Examination of the effect of the himA and himD mutants of E. coli on the maintenance of plasmid R6K has revealed that the gamma origin-containing replicons cannot be established in any of the mutants deficient in the production of E. coli Integration Host Factor (IHF). Contrary, the R6K derivatives containing other origins of the plasmid (alpha and/or beta) replicate in a host lacking functional IHF protein. We show that IHF protein binds specifically to a segment of the replication region which is essential for the activity of all three R6K origins. Mapping the IHF binding sequence with neocarzinostatin showed that the protein protects three segments of the origin: two strong binding sites reside within an AT-rich block, while the third, considerably weaker site is separated from the other two by a cluster of the seven 22 bp direct repeats. These seven repeats have been shown previously to bind the R6K-encoded initiator protein pi. We also demonstrate that the establishment of pi-origin complexes prior to IHF addition prevents the binding of the IHF protein to the gamma origin. The binding sequences of IHF and pi proteins do not overlap, therefore, we propose that the binding of pi protein alters the structure of the DNA and thereby prevents the subsequent binding of IHF protein.

Structure of the lamprey yolk lipid-protein complex lipovitellin-phosvitin at 2.8 A resolution

The X-ray crystallographic structure of the lipid-protein complex lipovitellin-phosvitin has been determined with the multiple isomorphous replacement method using four heavy-atom derivatives. Lamprey yolk lipovitellin-phosvitin is a dimeric molecule of molecular weight 352,000. The monomer consists of three polypeptide chains. The smallest is known as phosvitin and has an extremely high phosphoserine content. The monomeric unit also contains about 16% (w/w) of non-covalently bound lipid, probably in a monolayer or bilayer-like configuration. Within each monomer is a "cavity" or region of low electron density. The cavity has a volume of about 68,000 A3 and is believed to contain the lipid in a presumably disordered state. The cavity is roughly conical in shape and is lined on two sides by seven and eight-stranded antiparallel beta-sheets. The base of the cavity opens away from the intersubunit interface, but appears partially closed off from solvent regions by additional antiparallel beta-sheet structure. The beta-sheets lining the sides of the cavity are surrounded by a shell of two curved layers of 16 interconnected helices. The helices in either layer of the shell are all roughly parallel to each other and antiparallel to all of the helices of the other layer. The connectivity of the helices resembles a "superhelix" and is different from the connectivities seen in proteins containing four-helix bundles. There are an estimated 1300 amino acids in lamprey lipovitellin-phosvitin and almost 1000 alanine residues have been modeled into electron density. The remaining residues are assumed to be disordered.

Structural comparison of the prokaryotic ribosomal proteins L7/L12 and L30

The structures of two prokaryotic ribosomal proteins, the carboxyterminal half of L7/L12 from Escherichia coli (L12CTF) and L30 from Bacilus stearothermophilus display a remarkably similar fold in which alpha-helices pack onto one side of an antiparallel, three-stranded, beta-pleated sheet. A detailed comparison of the structures by least-squares methods reveals that more than two-thirds of the alpha carbons can be superimposed with a root mean square distance of 2.33 A. The principal difference is an extra alpha-helix in L12CTF. The sequences of the proteins display a distinct conservation in regions which are crucial to the common fold, in particular the hydrophobic core. It is proposed that the similarity is a result of divergent evolution.

Crystal structure of a prokaryotic ribosomal protein

The structure of ribosomal protein L30 from Bacillus stearothermophilus has been solved to a resolution of 2.5 A. The molecule is somewhat elongated and contains two helices and a three-stranded, anti-parallel beta-pleated sheet. The protein fold, in which helices pack on the same side of the sheet, generates a simple helix-sheet, two-layered motif. It is possible to distinguish three hydrophobic patches on the molecular surface, and one end has six isolated arginine and lysine residues. It is proposed that these reflect sites of protein-protein and protein-RNA interaction, respectively. The protein fold is very similar to that of the only other known ribosomal protein structure, L7/L12 from Escherichia coli, and, based on this similarity, an attempt is made to align the amino acid sequences of the two proteins.

3-A resolution structure of a protein with histone-like properties in prokaryotes

The 3-A structure of DNA-binding protein II, which exhibits histone-like properties in bacteria, has been determined. The molecule is dimeric and appears to bind to the phosphate backbone of DNA through two symmetry-related arms. A mechanism by which the protein induces DNA supercoiling is proposed.

Proteins of the Bacillus stearothermophilus ribosome. Crystallization of proteins L30 and S5

Proteins L30 and S5 from the 50 S and 30 S subunits, respectively, of the Bacillus stearothermophilus ribosome have been crystallized. L30 crystals are tetragonal and the space group is P4(1)2(1)2 (or P4(3)2(1)2) with cell dimensions a = b = 46.3 A and c = 61.4 A. S5 crystals are trigonal with the space group P3(1)21 (or P3(2)21) and cell dimensions a = b = 59.3 A and c = 109.8 A. In both cases, there appears to be a single molecule in the asymmetric unit.

Proteins of the Bacillus stearothermophilus ribosome. A 5 A structure analysis of protein S5

The structure of protein S5 from the small subunit of the Bacillus stearothermophilus ribosome is described to a resolution of 5 A. The molecular boundary is visible and shows the protein to be essentially compact although slightly elongated in one dimension.

Proteins of the Bacillus stearothermophilus ribosome. A low resolution crystal analysis of protein L30

The 5 A resolution crystal structure analysis of ribosomal protein L30 from Bacillus stearothermophilus is described. The molecule is shown to be compact and extend to about 25-30 A in each dimension.