P3548Noninvasive estimation of left ventricular diastolic function in patients with hypertension and normal ejection fraction using 3-dimensional speckle tracking echocardiography

Background

Left ventricular (LV) relaxation (eTau) and pulmonary capillary wedge pressure (ePCWP) were reported to be estimated by speckle tracking echocardiography (STE). LV camber stiffness (e-c stiffness) may be estimated with the use of 2 diastolic pressure-volume coordinates. The minimum diastolic pressure (mP) is reported to have a strong correlation with Tau.

Purpose

We sought to examine the impact of hypertension on LV diastolic function and LA properties and to elucidate the feature of hypertensive heart failure with preserved EF (HFpEF).

Methods

The e', E/e', Tau, PCWP, LVEDP, LV stiffness, LAV, LA emptying function (LAEF) and LA strain were examined in 53 controls (age 66±11), 136 hypertensive patients (HTN) with normal EF (69±11) and 39 HFpEF (77±14). ePCWP and estimated EDP (eEDP) was calculated as previously reported. Tau was calculated as isovolumic relaxation time/(ln 0.9 x systolic blood pressure − ln PCWP). Myocardial stiffness (e-m stiffness) was estimated as LVED stress/LV strain. LV c-stiffness was calculated as LV pressure change (from mP to EDP) obtained by catheterization divided by LV volume change. Estimated LV c-stiffness (e-c-stiffness) was noninvasively obtained using e-mP and e-EDP. The eTau, eEDP and e-mP by STE were validated by catheterization (n=126).

Results

The mP had a good correlation with Tau (r=0.70, p<0.01). The eTau, eEDP and e-mP by STE had a good correlation with those by catheterization (r=0.75, 0.63 and 0.70, p<0.01). Multivariate analysis revealed that ePCWP and LA strain were independent predictors of HFpEF.

LV diastoric function Variables Control HTN HFpEF LVEF, % 68±6 68±8 63±9*+ LV longitudinal strain x (s–1) 19.1±3.0 16.8±4.3* 14.5±5.1*+ E/e' 9.2±2.6 11.6±4.5* 15.9±7.9*+ eTau, ms 35±12 48±17* 59±17*+ ePCWP, mmHg 7.3±2.7 8.3±4.3 15.0±4.4*+ eLVEDP, mmHg 9.4±2.2 10.4±3.5 15.9±3.7*+ LV e-myocardial stiffness, kdynes/cm 0.56±0.25 0.69±0.56 1.27±0.71*+ LV e-chamber stiffness, mmHg/ml 0.19±0.06 0.20±0.08 0.36±0.19*+ Maximum LAVI, ml/m2 42±15 50±21* 68±17*+ Total LAEF, % 55±7 51±11 36±12*+ LA peak strain 41±15 40±17 19±8*+ *p<0.05 vs Control, +p<0.05 vs HTN.

Conclusion

We demonstrated that LV diastolic function in HTN may be accurately and noninvasively evaluated by STE.

Primary Structure of a Base Non-specific and Adenylic Acid Preferential Ribonuclease from the Fruit Bodies ofLentinus edodes

The complete primary structure of a base non-specific and adenylic acid preferential RNase (RNase Le2) from the fruit bodies of Lentinus edodes was analyzed. The sequence was mostly determined by analysis of the peptides generated by V8 protease digestion and BrCN cleavage (including alpha-chymotryptic, and V8 protease digest of BrCN fragments). It consists of 239 amino acid residues. The molecular weight is 25831. The location of 10 half cystine residues were almost superimposable on those of known fungal RNases of the RNase T2 family. The sequence homologies between RNase Le2 and four known fungal RNases of the RNase T2 family, RNase T2, RNase M, RNase Trv, and RNase Rh, are 102, 103, 109, and 74, respectively. The homologous sequences are concentrated around the three histidines, which are supposed to form the active site of RNase T2 family RNases.

JDP2 suppresses adipocyte differentiation by regulating histone acetylation

Among the events that control cellular differentiation, the acetylation of histones plays a critical role in the regulation of transcription and the modification of chromatin. Jun dimerization protein 2 (JDP2), a member of the AP-1 family, is an inhibitor of such acetylation and contributes to the maintenance of chromatin structure. In an examination of Jdp2 'knock-out' (KO) mice, we observed elevated numbers of white adipocytes and significant accumulation of lipid in the adipose tissue in sections of scapulae. In addition, mouse embryo fibroblasts (MEFs) from Jdp2 KO mice were more susceptible to adipocyte differentiation in response to hormonal induction and members of the CCAAT/enhancer-binding proteins (C/EBP) gene family were expressed at levels higher than MEFs from wild-type mice. Furthermore, JDP2 inhibited both the acetylation of histone H3 in the promoter of the gene for C/EBPdelta and transcription from this promoter. Our data indicate that JDP2 plays a key role as a repressor of adipocyte differentiation by regulating the expression of the gene for C/EBPdelta via inhibition of histone acetylation.

Determination of vitamin B12 using the enzyme glycerol dehydrase

Glycerol dehydrase is an enzyme that catalyzes dehydration of glycerol into beta-propionaldehyde. It requires 5'-deoxyadenosylcobalamin, one of the forms of vitamin B12, as a coenzyme. The enzyme is inactivated in vitro by all forms of vitamin B12 stoichiometrically. The objective of this study was to determine vitamin B12 content by utilizing the inactivation of the enzyme by vitamin B12. After various examinations, an excellent standard curve was obtained up to 1 pmol vitamin B12 using 14 mU of the enzyme per tube. Glycerol dehydrase does not respond to vitamin B12 if it is bound to haptocorrin, a vitamin B12-binding protein. This necessitates a procedure for extraction of vitamin B12 from samples before assay. The enzyme was less inactivated by 5'-deoxyadenosylcobalamin than any other form of vitamin B12. However, this did not matter because all forms of vitamin B12 were converted into cyanocobalamin during the extraction procedure cited above, which was performed in a buffer containing potassium cyanide.

One-dimensional orbital excitations in vanadium oxides

The d electron orbital is a hidden but important degree of freedom controlling novel properties of transition-metal oxides. A one-dimensional orbital system is especially intriguing due to its enhanced quantum fluctuation. We present a combined experimental and theoretical study on the Raman scattering spectra in perovskite oxides NdVO(3) and LaVO(3) to prove that the quasi-one-dimensional orbital chain described by fermionic pseudospinons bears orbital excitations exchanging occupied orbital states on the neighboring sites, termed a two-orbiton in analogy with two-magnon.

Enzymatic properties of sialic acid binding lectin from Rana catesbeiana modified with a water-soluble carbodiimide in the presence of various nucleophiles

The anti-tumor activity of sialic acid binding lectin from Rana catesbeiana (cSBL) was increased by chemical modification with a water-soluble carbodiimide (EDC) in the presence of nucleophiles such as ethylenediamine and glycine methylester. Investigations on ribonuclease (RNase) activities of the modified cSBLs were conducted to elucidate the fundamental mechanisms underlying enhancement of the anti-tumor activity conferred by these modifications. The following three characteristics were observed with modification. (i) RNase activity of the modified cSBL was enhanced towards double stranded RNA and RNA-oligo dA hybrids. The activity increase was observed even under physiologic ionic strength conditions; (ii) RNase activity of the modified cSBL towards single stranded RNA and poly U decreased, while the activity towards poly C was unaffected; (iii) the base preference of the B2 base recognition site of modified cSBL decreased for guanine. On the contrary, the preference for cytosine and adenine increased. This result may explain why the RNase activity towards poly C was not affected by EDC-modification as mentioned above.

Amino acid sequence of a trypsin inhibitor from a Spirometra (Spirometra erinaceieuropaei)

A trypsin inhibitor that is highly homologous with bovine pancreatic trypsin inhibitor (BPTI) was co-purified along with RNase from Spirometra (Spirometra erinaceieuropaei). The amino acid sequence of this inhibitor (SETI) and the nucleotide sequence of the cDNA encoding this protein were determined by protein chemistry and gene technology. SETI contains 68 amino acid residues and has a molecular mass of 7,798 Da. SETI has 31 amino acid residues that are identical with BPTI's sequence, including 6 half-cystine and 5 aromatic amino acid residues. The active site Lys residue in BPTI is replaced by an Arg residue in SETI. SETI is an effective inhibitor of trypsin and moderately inhibits a-chymotrypsin, but less inhibits elastase or subtilisin. SETI was expressed by E. coli containing a PelB vector carrying the SETI encoding cDNA; an expression yield of 0.68 mg/l was obtained. The phylogenetic relationship of SETI and the other BPTI-like trypsin inhibitors was analyzed using most likelihood inference methods.

Effect of modification of the carboxyl groups of the sialic acid binding lectin from bullfrog (Rana catesbeiana) oocyte on anti-tumor activity

The sialic acid binding lectin from bullfrog Rana catesbeiana oocyte (cSBL) is known to have anti-tumor activity. In order to investigate the relationship between the net charge of cSBL and its anti-tumor effect, cSBL was modified with a water-soluble carbodiimide (EDC) in the presence of three kinds of nucleophiles, taurine, glycine methylester and ethylenediamine. cSBL having four carboxyl groups was partially modified (ca. 2 residues). The anti-tumor activity of modified cSBLs was in the order of ethylenediamine-modified cSBL > glycine methylester-modified cSBL > taurine modified cSBL > or = native cSBL. The results suggested that anti-tumor activity seems to increase with the increase in positive net charge, possibly enhancing the interaction of cSBL with sialoglycoprotein on the surface of tumor cells. The ribonuclease activity of ethylenediamine-modified cSBL decreased with the progress of the reaction, but the number of internalized molecules in the tumor cell increased. Thus, for antitumor activity, a higher incorporation of cSBL with reasonable RNase activity seems to be more important than total RNase activity.

Justification of measurement of eight congeners levels instead of twenty congeners of dioxins for mass screening of human exposure

Measurement of blood dioxin levels to monitor human exposure is tedious and expensive work, although high-resolution mass spectrometers equipped with high-resolution gas chromatography are becoming relatively common in Japan. The Ministry of Health and Welfare and the Environmental Agency require measurement of 17 dioxins, seven PCDDs and 10 PCDFs, according to a statement in "Dioxin Measurement Guidelines" published in 1997. Additionally, three coplanar polychlorinated biphenyls, for which TEFs were determined, have been included for measurement ad libitum. Recently, we have examined 316 blood samples from four groups of subjects, living in areas 5 km away from any incinerator (A), within 2 km from incinerators that emitted slightly higher levels of dioxins than the allowed level (higher than 80 ng/Nm3) (B), within 2 km of an incinerator which emitted a high level of dioxin (C), and workers at this incinerator (D), for dioxin levels by measuring 20 congeners, including three coplanar PCBs. The average pg TEQ/g lipid values were 23.8 +/- 12.3, 25.6 +/- 11.6, 39.1 +/- 18.8 and 100.7 +/- 127.4 for A, B, C and D, respectively. It was found that more than 90% of the total TEQs of the subjects in all groups were accounted for by eight congeners, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, 3,3',4,4',5-PeCB, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF and 2,3,4,6,7,8-HxCDF. This is also the case for a further 30 blood samples that had no connection with incinerators. Further, regression analysis of the 346 samples leads to an equation of y = 1.109x - 1.077, with a correlation coefficient, r = 0.9996. Here, y = total pg TEQ of 20 congeners/g lipid of blood, and x = total pg TEQs of eight congeners/g lipid. Accordingly, we propose that measurement of eight instead of 20 congeners is appropriate to obtain dioxin TEQ values of blood, at low cost, with high accuracy and with high efficiency, in a short time.

Amino acid sequence and characterization of a rice bran ribonuclease

A base-nonspecific and acid ribonuclease (RNase Os) belonging to the RNase T2 family was purified from rice bran to a homogeneous state by SDS-PAGE. The primary structure of RNase Os was determined by protein chemistry and molecular cloning. The RNase Os was a simple protein and consisted of 205 amino acid residues. Its molecular weight was 22578 and its amino acid sequence showed that it was most similar to barley RNase among the known RNase T2 family enzymes having 157 amino acid residues identical with barley RNase. However, its N-terminus was blocked by a gamma-pyroglutamyl residue. The optimal pH of RNase Os was around 5.5. The base preference at the B1 and B2 site of RNase Os was estimated from the rates of hydrolysis of 16 dinucleoside phosphates, to be guanine as the case of RNase LE from tomato. RNase Os was successfully expressed from yeast cells using the E. coli yeast expression vector pYE-RNAP.

Actinohivin, a novel anti-HIV protein from an actinomycete that inhibits syncytium formation: isolation, characterization, and biological activities

Blocking human immunodeficiency virus (HIV) entry into target cells is an important goal of HIV and acquired immune deficiency syndrome (AIDS) therapies. We have searched for anti-HIV substances from microorganisms using a syncytium formation assay system constructed with HeLa/CD4/Lac-Z and HeLa/T-env/Tat cells. We discovered a novel anti-HIV protein that inhibits syncytium formation, designated as actinohivin, from a cultured broth of a soil isolate, actinomycete strain K97-0003. ESI mass spectrometry of actinohivin isolated from the culture filtrate showed an ion with molecular mass of 12,520.3 Da. The amino acid sequence was determined by N-terminal Edman degradation of the intact protein and peptide fragments formed by endoproteinase digestions. Actinohivin consists of a 114-amino-acid chain that exhibits internal sequence triplication. Actinohivin inhibited both T-cell and macrophage tropic syncytium formation, with IC(50) values of 60 and 700 nM, respectively, and the cytopathic effect of HIV-1(IIIB) in MT-4 cells, with IC(50) value of 230 nM.

Enzymatic properties of phenylalanine101 mutant enzyme of ribonuclease rh from Rhizopus niveus

To investigate the role of Phe101, a component of a base recognition site (B2 site) of a base-nonspecific RNase Rh from Rhizopus niveus, we prepared several enzymes mutated at this position, F101W, F101L, F101I, F101A, F101Q, F101R, and F101K, and their enzymatic activities towards RNA, 16 dinucleoside phosphates, and 2', 3'-cyclic pyrimidine nucleotides were measured. Enzymatic activity toward RNA of F101W, F101L, and F101I were about 7, 20, and 3.8% of the native enzyme, respectively, and those of the other mutants were less than 1% of the RNase Rh. Similar results were also obtained with GpG as substrate. Thus, it was concluded that Phe101 is a very important residue as a component of the B2 site of RNase Rh, and its role could be replaced by Leu, then Trp and Ile, though in less effectively. The results suggested that some kind of interaction between B2 base and the side chain of amino acid residue at the 101th position, such as pi/pi or CH/pi interaction is very important for the enzymatic activity of RNase Rh. The mutation of Phe101 markedly affected the enzymatic activity toward dinucleoside phosphates and polymer substrates, but only moderately the rate of hydrolysis of cyclic nucleotides, indicating the presence of secondary effect of the mutation on B1 site.

Relationship of two ribonucleases with molecular masses of 45 kDa and 37 kDa from the culture medium of Lentinus edodes

Lentinus edodes (shiitake) produces three base non- specific and acid ribonucleases, RNase Le2, RNase Le37 and RNase Le45. The primary structures of the former two RNases, having molecular masses about 24 and 37 kDa, respectively, have been elucidated to be members of the RNase T2 family. The latter two are excreted from mycelia into the medium. In this report, we estimated the primary structure of RNase Le45 using the following experimental evidence. (i) The partial amino acid sequence of RNase Le45 determined that up to about 60% of total protein was identical with that of RNase Le37. (ii) The amino acid composition of RNase Le45 was identical to that of RNase Le37. (iii) The elution profiles on HPLC of lysylendopeptidase and Staphylococcus aureus V8 protease digests of RCM-RNase Le45 (reduced and S-carboxymethylated RNase Le45) were very similar to those of RNase Le37, except for the absence of C-terminus peptide which contained O-glycosylated peptides. However, RNase Le45 contained about 70 residues of mannose and 4 residues of hexosamine. These values were more than twice those of RNase Le37. (iv) RNase Le45 was immunologically indistinguishable from RNase Le37. (v) After treatment with both glycosidase EndoH and alpha-mannosidase, RNases Le37 and Le45 gave complex bands by slab-gel electrophoresis. However, one of the major bands with the highest mobility from RNase Le45 and Le37 showed the molecular mass of 29 kDa in common, which is slightly larger than that of RNase Le2 containing no carbohydrate. These results indicated that RNase Le45 is an enzyme which is a heavily glycosylated species of RNase Le37.

Amino acid sequence of a nuclease (nuclease Le1) from Lentinus edodes

The fruit bodies of Lentinus edodes produce two acid nucleases, nucleases Le1 and Le3, both of which are thought to be candidates for the enzymes producing a tasty substance, 5'-GMP. To obtain the basic information on the mechanism of production of 5'-GMP, and structure-function relationship of these nucleases, the primary structure of nuclease Le1 was estimated by both protein chemistry and gene cloning. Nuclease Le1 is a glycoprotein and consists of 290 amino acid residues, and about 2 and 6 residues of hexosamine and neutral sugar, respectively. The nucleotide sequence of cDNA and genomic DNA encoding nuclease Le1 indicated the presence of 20 amino acid residues of a signal peptide. Nuclease Le1 has 115 and 108 residues of identical amino acid residues with nucleases P1 and S, respectively. The amino acid residues concerning the coordination with Zn2+ in nuclease P1 are all conserved in nuclease Le1. Nuclease Le1 contains 8 half-cystine residues and 4 of them are located at the same places as those of nucleases P1 and S.

Relationship between breast milk feeding and atopic dermatitis in children

OBJECTIVE

To determine whether or not the breast milk feeding has a role in the prevalence of atopic dermatitis among children.

METHODS

The target population of the study was all children participating in health check-up program for 3-year-old children in 60 municipalities locating 10 selected prefectures during designated 2 months between October and December 1997. Using a questionnaire, information on nutrition in infants (breast milk only, bottled milk only, or mixed), parity, mothers' age at birth, and a history of atopic dermatitis was obtained. Besides, data on potential confounding factors were obtained.

RESULTS

Questionnaires from 3856 children (81.6% of those who were to participate in the programs, and 96.4% of children who participated them) were analyzed. After the adjustment for all potential confounding factors using unconditional logistic models, the risk of atopic dermatitis was slightly higher among children with breast milk (odds ratio [OR] = 1.16 with 95% confidence interval [CI] 0.96-1.40). Mothers' age at birth (OR for those who were more than 30 years or older in comparison with those who were younger than 30 years = 1.15; 95% CI, 0.96-1.37) and those with second or later parity orders (OR = 1.14, 95% CI; 0.95-1.35) showed odds ratios that were higher than unity without statistical significance.

CONCLUSION

Breast milk elevates the risk of atopic dermatitis slightly without statistical significance; the risk may be, however, higher in children in second or later parity orders.

Amino acids and peptides. LVII. Synthetic peptide with a sequence of ribonuclease from Sulfolobus solfataricus, SSR(1-62), does not function as an RNase

The 62 residue peptide, SSR(1-62), whose sequence corresponds to that of ribonuclease (RNase) from Sulfolobus solfataricus, and its related peptides, SSR(1-22) and SSR(10-62), were chemically synthesized and their RNase activity and DNA-binding activity were examined. The RNase activity assay using yeast RNA or tRNA(fMet) as substrate showed that the synthetic peptide SSR(1-62) did not hydrolyze yeast RNA or tRNA(fMet). These data were not consistent with previous reports that both the native peptide isolated from S. solfataricus [Fusi et al. (1993) Eur. J. Biochem. 211, 305-311] and the recombinant peptide expressed in Escherichia coli [Fusi et al. (1995) Gene 154, 99-103] were able to hydrolyze tRNA(fMet). However, the synthetic SSR(1-62) exhibited DNA-binding activity. In the presence of synthetic SSR(1-62), the cleavage of DNA (plasmid pUCRh2-4) by restriction endonuclease (EcoRI) was not observed, suggesting that synthetic SSR(1-62) bound to DNA protected DNA from its enzymatic digestion. Neither SSR(1-22) nor SSR(10-62) prevented DNA from being cleaved by a restriction enzyme. These findings strongly suggest the importance of not only the N-terminal region of SSR(1-62) but also the C-terminal region for DNA-binding. Circular dichroism spectroscopy of synthetic SSR(1-62) indicated a beta-sheet conformation, in contrast with synthetic SSR(1-22), which exhibited an unordered conformation.

cDNA-derived amino acid sequence of acetoacetyl-CoA synthetase from rat liver

In order to examine the primary structure of acetoacetyl-CoA synthetase (acetoacetate-CoA ligase, EC 6.2.1.16; AA-CoA synthetase), the cDNA clone encoding this enzyme has been isolated from the cDNA library which was prepared from the liver of rat fed a diet supplemented with 4% cholestyramine and 0.4% pravastatin for 4 days. Nucleotide sequence analysis of cloned cDNA revealed that AA-CoA synthetase of rat liver contains an open reading frame of 2019 nucleotides, and the deduced amino acid sequence (672 amino acid residues) bears 25.0 and 38.9% homologies with acetyl-CoA synthetases of Saccharomyces cerevisiae and Archaeoglobus fulgidus, respectively.

Amino acid sequence of an unique ribonuclease with a C-terminus rich in O-glycosylated serine and threonine from culture medium of Lentinus edodes

The mushroom Lentinus edodes produces three base-non-specific and acid ribonucleases, RNases Le2, Le37, and Le45. The latter two are excreted from mycelia into the medium. The primary structure of RNase Le37, which had a molecular mass of 37 kDa, was sequenced. It was a member of the RNase T2 family, as is RNase Le2. RNase Le37 was some 30 amino acid residues longer at the C-terminal end than RNase Le2. The C-terminal region of RNase LE37 was rich in O-glycosylated serine and threonine. In fungal glucoamylases and chitinases, which hydrolyze raw-starch and chitin, respectively, have structures resembling the structure of the C-terminal of RNase Le37.

Involvement of a cellular glycolytic enzyme, phosphoglycerate kinase, in Sendai virus transcription

In vitro mRNA synthesis of Sendai virus is almost entirely dependent on the addition of cellular proteins (host factors). Previous studies indicated that the host factor activity from bovine brain was resolved into at least two complementary fractions, one of which may be tubulin. In this study, the host factor activity that stimulates the transcription in the presence of tubulin was further purified from bovine brain. This fraction was found to contain at least two complementary factors, and one of them was purified to a single polypeptide chain with an apparent M(r) of 46,000 (p46). From the amino acid sequence, biochemical, and immunological analyses, p46 was identified as a glycolytic enzyme, phosphoglycerate kinase (PGK). Purified native PGK from rabbit and yeast, and a recombinant human PGK substituted for p46. Although, as previously suggested, tubulin was involved in the transcription initiation complex formation by being integrated into the complex, p46 and its complementary factor had little effect on the complex formation. On the other hand, when p46 and the complementary factor were added to the RNA chain elongation reaction from the isolated initiation complex formed with tubulin, mRNA synthesis was dramatically stimulated. The enzymatic activity per se of PGK did not seem to be required for its activity. West-Western blot analysis showed that PGK could directly interact with tubulin. These data suggest that PGK stimulates Sendai virus mRNA synthesis at the elongation step, probably through its interaction with tubulin in the initiation complex.

Fiber-coupled writing and reading in magneto-optical media

Curie point writing and Kerr signal reading in magneto-optical disk media are accomplished with a flint glass single-mode fiber that connects the optical source (laser diode)-detector and the magneto-optical medium. The Kerr signal is detected sensitively with high stability against external disturbances such as stress and deformation of the fiber. This technique offers a simple, flexible, light, movable, and remotely settable means for signal processing of magneto-optical devices.

Purification and characterization of caffeine synthase from tea leaves

Caffeine synthase (CS), the S-adenosylmethionine-dependent N-methyltransferase involved in the last two steps of caffeine biosynthesis, was extracted from young tea (Camellia sinensis) leaves; the CS was purified 520-fold to apparent homogeneity and a final specific activity of 5.7 nkat mg-1 protein by ammonium sulfate fractionation and hydroxyapatite, anion-exchange, adenosine-agarose, and gel-filtration chromatography. The native enzyme was monomeric with an apparent molecular mass of 61 kD as estimated by gel-filtration chromatography and 41 kD as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme displayed a sharp pH optimum of 8.5. The final preparation exhibited 3- and 1-N-methyltransferase activity with a broad substrate specificity, showing high activity toward paraxanthine, 7-methylxanthine, and theobromine and low activity with 3-methylxanthine and 1-methylxanthine. However, the enzyme had no 7-N-methyltransferase activity toward xanthosine and xanthosine 5'-monophosphate. The Km values of CS for paraxanthine, theobromine, 7-methylxanthine, and S-adenosylmethionine were 24, 186, 344, and 21 microM, respectively. The possible role and regulation of CS in purine alkaloid biosynthesis in tea leaves are discussed. The 20-amino acid N-terminal sequence for CS showed little homology with other methyltransferases.

Induction of apoptosis in vitro and in vivo by H-1 parvovirus infection

Apoptosis induced by H-1 parvovirus infection was investigated in C6 rat glioblastoma cells and in newborn rats. Apoptotic changes, such as chromatin condensation, the appearance of apoptotic nuclear bodies and oligonucleosomal DNA ladders, were observed in infected C6 cells 2 days after infection. Inhibitor assay results suggest that a caspase-3-dependent apoptosis activation pathway is induced by H-1 virus infection in C6 cells. Observations made in vivo revealed that the number of apoptotic cells increased in the infected cerebellum, coinciding with known virus infection sites.

Characterization and primary structure of a base non-specific and acid ribonuclease from Dictyostelium discoideum

A base non-specific and acid RNase was isolated from cellular slime mold (Dictyostelium discoideum) cells in a homogeneous state (about 2.4 kDa) by SDS-polyacrylamide gel electrophoresis. The RNase (RNase DdI) has a pH optimum of 5.0. The amino acid sequence of RNase DdI was determined by a combination of protein chemistry, a search of Data base, Dicty cDB and further sequence analysis of cDNA from the same bank. RNase DdI consists of 198 amino acid residues, and about 13.3, 0.9, 1.2, 3.3, and 1.0 residues of mannose, xylose, glucose, GlcNAc, and GalNAc, respectively. RNase DdI has two characteristic conserved segments of the RNase T2 family, and thus belongs to the RNase T2 family. Considering the fact that most of the RNase activity of D. discoideum is present in the lysosomal fraction [Wiener and Ashworth (1970) Biochem. J. 118, 505-512], it was concluded that the lysosomal RNase in D. discoideum is a member of the RNase T2 family. The amino acid sequence of RNase DdI is highly homologous with that of Physarum polycephalum RNase (RNase Phyb), and its amino acid sequence seems to be similar to those of plant/animal type RNases, rather than fungal RNases. The location of RNase DdI in the phylogenetic tree of the RNase T2 family was estimated.

Prevalence of "orphan" parvovirus infections in mice and rats

"Orphan" parvovirus (OPV) infection in laboratory mice and rats was serologically surveyed for 465 mouse sera and 271 rat sera collected from 1986 to 1987 and from 1993 to 1996 in Japan. The results suggest that parvovirus infection is rare in mice but common in rats (positive rate: 13-22%) and that most putative viruses were OPVs. OPV is therefore considered to already have been harbored for at least ten years in Japan.

A protease sensitive region of plant and animal ribonucleases belonging to the RNase T2 family

Recombinant RNase LE from tomato and squid liver RNase Tp, typical plant/animal type RNases belonging to the RNase T2 family, were subjected to limited digestion with several proteases, and the cleavage sites were analyzed by Edman degradation. Recombinant RNase LE was cleaved specifically at the 24th Lys by lysylendopeptidase and trypsin, and RNase Tp was cleaved at the 21st Glu by V8 protease. These cleavage sites are located very close to those where the cleavage during preparation of several animal RNase T2 family enzymes was observed. From this finding, it was concluded that the short segment around the 20th amino acid residue in plant/animal RNases is located on the surface of the molecules and forms loops, and is thus very sensitive to proteases.

Primary structure of porcine spleen ribonuclease: sequence homology

The primary structure of porcine spleen RNase (RNase Psp1) was investigated as a mean of assessing the structure-function relationship of base non-specific ribonucleases of animal origin. N-terminal analysis of RNase Psp1 yielded three N-terminal sequences. These peptides were separated by gel-filtration on Superdex 75HR, after reduction and S-carboxymethylation of RNase Psp1. Determination of the amino-acid sequence of these peptides indicated that the RNase Psp1 preparation consisted of three peptides having 20 (RCM RNase Psp1 pep1), 15 (RCM RNase Psp1 pep2), and 164 (RCM RNase Psp1 pro) amino-acid residues, respectively. It possessed two unique segments containing most of the active site amino-acid residues of the RNases of the RNase T2 family. The alignment of these three peptides in RNase Psp1 was determined by comparison with the other enzymes in the RNase T2 family. The overall results showed that RCM RNase Psp1 pep1 and RCM RNase Psp1 pep2 are derived from the N-terminal and C-terminal regions of RNase Psp1, respectively, probably by processing by some protease. The molecular mass of the protein moiety of RNase Psp1 was 23235 Da.

Primary structure of a squid acid and base non-specific ribonuclease

Squid (Todarodes pacificus) liver RNase (RNase Tp) was purified. RNase Tp was a base non-specific and acid RNase. Upon hydrolysis of RNA, RNase Tp released four mononucleotides in the order of G > A > U > C. RNase Tp consisted of two peptides with 198 and 23 amino acid residues. The amino acid sequences of these peptides were analyzed. The large peptide had two unique segments containing most of the active site amino acid residues of RNase T2 family enzymes. From the comparison of the sequence of short peptide with the sequences of the other RNase belonging to RNase T2 family RNases, it was found that the amino acid sequence of the short peptide was very similar to that of the C-terminal portion of RNases of the RNase T2 family. Thus, we concluded that the short peptide was a C-terminal part of RNase Tp. The molecular mass of the protein moiety of RNase Tp was 25,582 daltons. The amino acid sequence of RNase Tp most resembles that of oyster RNase (91 amino acid residues identical) in the RNase T2 family RNases. However, the N-terminal portion of RNase Tp was unusually similar to those of plant RNases, rather than the other animal RNases.

Primary structure of porcine spleen ribonuclease: sequence homology

The primary structure of porcine spleen RNase (RNase Psp1) was investigated as a mean of assessing the structure-function relationship of base non-specific ribonucleases of animal origin. N-terminal analysis of RNase Psp1 yielded three N-terminal sequences. These peptides were separated by gel-filtration on Superdex 75HR, after reduction and S-carboxymethylation of RNase Psp1. Determination of the amino-acid sequence of these peptides indicated that the RNase Psp1 preparation consisted of three peptides having 20 (RCM RNase Psp1 pep1), 15 (RCM RNase Psp1 pep2), and 164 (RCM RNase Psp1 pro) amino-acid residues, respectively. It possessed two unique segments containing most of the active site amino-acid residues of the RNases of the RNase T2 family. The alignment of these three peptides in RNase Psp1 was determined by comparison with the other enzymes in the RNase T2 family. The overall results showed that RCM RNase Psp1 pep1 and RCM RNase Psp1 pep2 are derived from the N-terminal and C-terminal regions of RNase Psp1, respectively, probably by processing by some protease. The molecular mass of the protein moiety of RNase Psp1 was 23235 Da.

Enzymatic properties of double mutant enzymes at Asp51 and Trp49 and Asp51 and Tyr57 of RNase Rh from Rhizopus niveus

Mutation of Asp51 of a base-nonspecific RNase, RNase Rh, to Ser, Thr, or Gln makes the enzyme more preferential for the dinucleoside phosphate (XpY) having G and C at the 5'-side (X). On the other hand the mutation of one of the B1 site components, Tyr57 to Trp, and Trp49 to Phe makes the enzyme more preferential for purine bases and pyrimidine bases, respectively. In this study, to obtain more specific RNases and RNases with different base specificity, we prepared double-mutant enzymes that have Ser, Thr, and Asn at the 51st position and Trp at the 57th position or Phe at the 49th position, and their enzymatic specificities were studied with XpYs as substrates. The double-mutant enzymes D51SY57W and D51TY57W are more guanylic acid preferential than the mother single-mutant enzymes, D51S and D51T, respectively. They are extremely guanylic preferential RNases. D51NY57W is more a guanylic acid preferential enzyme than D51N, but cytidylic acid preference is of a similar order to that of D51N. The double mutant enzymes D51NW49F and D51TW49F showed an increased cytidylic acid preference as well as guanylic acid preference as compared to the mother single-mutant enzymes, D51T and D51N. The results of analysis of base specificity by the release of mononucleotides from RNA and the rates of hydrolysis of homopolynucleotides led to the same conclusion as in the case of the hydrolysis of XpY.

Primary structure of base non-specific and acid ribonuclease from bullfrog (Rana catesbeiana)

A base non-specific acid ribonuclease (RNase RCL2) was purified from bullfrog liver [H. Yagi et al. Biol. Pharm. Bull., 18, 219-222 (1992)]. The sequence study and comparison of the amino acid sequence of the enzyme with homologous RNases from oyster, drosophila and chicken liver suggested that the RNase RCL2 consisted of two components, large protein fraction (182 amino acid residues) and peptide 2 (20 amino acid residues) or peptide 1 (18 amino acid residues), and that both components bind with disulfide bridge. The RNase preparation was probably formed from a single polypeptide protein by processing with some proteases. The amino acid sequence of RNase RCL2 showed that the RNase belongs to the RNase of RNase T2 family and its sequence most resembles chicken liver acid RNase. In RNase RCL2, the amino acid residues which consist of the active site and major base recognition site of RNase Rh, a typical RNase of RNase T2 family, are very well conserved except for Tyr57 (RNase Rh numbering), and part of the amino acid residues of the minor base recognition site (Phe101 and Pro92) are also conserved.

Role of histidine 46 in the hydrolysis and the reverse transphosphorylation reaction of RNase Rh from Rhizopus niveus

In order to study the reaction mechanism of RNase Rh from Rhizopus niveus, the rates of cleavage of four 2',3'-cyclic nucleotides by mutant enzymes of RNase Rh, H46F, H109F, E105Q, and K108L were measured. H46F is virtually inactive towards cyclic nucleotides, but H109F hydrolyzed these substrates at 0.7-4.5% of the rates of the native RNase Rh. The other mutants hydrolyzed 2',3'-cyclic nucleotides at 15-20% of the rates of the native enzyme. Relative enzymatic activities towards four cyclic nucleotides of H109F in the hydrolysis reaction (2nd step) were much higher than in the transphosphorylation reaction (the 1st step). In the presence of a 13-fold excess of uridine, H109F catalyzed the transphosphorylation reaction of 2',3'-cyclic AMP (A>p) to ApU. However, this reaction was not catalyzed by H46F mutant or native RNase Rh. These results showed that His46 is crucial to the hydrolysis reaction, and to the reversed reaction of the transphosphorylation reaction. We suggest that His46 in RNase Rh plays a major role in these reactions by acting as a base catalyst to activate water and the 5'-hydroxyl group of nucleosides, respectively.

The base specificities of tomato ribonuclease (RNase LE) and its Asp44 mutant enzyme expressed from yeast cells

RNase LE from cultured tomato cells is a member of the RNase T2 family. It is, however, distinguishable from RNase Rh from Rhizopus niveus, a typical RNase of the RNase T2 family, by its CD spectrum in the 200-250 nm region. In order to reinvestigate the base specificity of RNase LE and to study the role of Asn44 in RNase LE, which is considered to correspond to the base recognition site Asp51 of RNase Rh, RNase LE, and its Asp mutant at the 44th position were expressed from yeast cells with the same expression system as RNase Rh [K. Ohgi, et al., J. Biochem., 109, 776-785 (1991)]. RNase LE with four extra amino acid residues at the 2nd amino acid residue of mature RNase LE and its Asp44 mutant were secreted from yeast cells to give a yield of 10 mg/liter and 0.5 mg/liter culture broth, respectively. The expressed RNase LE (RNase RNAP LE) had the same characteristics as native RNase LE in the CD spectrum and specific activity. This is the first example of the expression of plant RNase from microbes and in sufficient amount to perform further enzymological research. The base specificity of RNase LE was guanylic acid preferential and that of N44D was changed to a more adenylic acid preference as compared to that of RNase LE. These experiments showed that Asn44 of RNase LE is crucial for base recognition as the case of Asp51 in RNASE Rh, and also suggested that the base recognition mechanism of RNase LE is very similar to that of RNase Rh.

Base specificity and primary structure of poly U-preferential ribonuclease from chicken liver

The primary structure and base specificity of chicken liver RNase CL1 which has been reported by Miura et al. [Chem. Pharm. Bull., 32, 4053-4060 (1984)] as poly U-preferential RNase, were extensively studied. The sequence study of this enzyme and comparison of the amino acid sequence of the enzyme with homologous RNases from oyster and Drosophila melanogaster suggested that RNase CL1 consists of three peptides with 17, 19, and 163 amino acid residues. The amino acid sequence of these three peptides were identified. The two small peptides are joined to the large peptide by disulfide bridges. The amino acid sequence of RNase CL1 had 62 (31.2%) and 63 residues (31.6%) identical with oyster RNase and D. melanogaster RNase, respectively, and belongs to the RNase T2 family RNase. Reassessment of the base specificity of RNase CL1 found that it is guanylic acid, then uridylic acid-preferential, and not poly U preferential.

Positive and negative host factors for Sendai virus transcription and their organ distribution in rat

In vitro mRNA synthesis by Sendai virus is almost entirely dependent on the addition of cellular proteins (positive host factors), one of which could be tubulin. In this study, we investigated the distribution of host factors in various rat organs. Extracts from the brain, thymus, heart, lung, testis, ovary, and uterus all supported in vitro Sendai virus transcription, among which the highest activity was obtained with the brain extract. On the other hand, little or no activity was detected in the liver, spleen, and kidney extracts. An inverse correlation between the apparent host factor activity to stimulate mRNA synthesis and RNase activity that hydrolyzes Sendai virus mRNAs was found, except in the liver extract. However, when a transcription initiation complex was isolated and subjected to RNA chain elongation reaction, all of the extracts including those from liver, spleen and kidney, were active. Immunoblotting showed that tubulin molecules were integrated in these initiation complexes, supporting the notion that tubulin is involved in the initiation complex formation. We also identified a transcription inhibitory activity without any detectable RNase activity in the liver extract. This negative host factor seemed to act on RNA chain elongation. It is likely that Sendai virus transcription is regulated by both positive and negative regulatory factors.

Enzymatic activities of several K108 mutants of ribonuclease (RNase) Rh isolated from Rhizopus niveus

We previously investigated the role of the Lys108 residue of ribonuclease (RNase) Rh from Rhizopus niveus, and suggested that Lys108 probably acts to stabilize the pentacovalent intermediate, and that an Arg residue could replace the role of Lys108. In RNase Le2 from Lentinus edodes, a homologous enzyme of RNase Rh, Lys108 is replaced by Thr. In this paper, the enzymatic properties of a K108T mutant and its analogous enzyme, K108S, were investigated to determine the effect of Thr and its analog, Ser at the 108th position on enzyme activity. The enzymatic properties of these mutant enzymes were compared with those of other mutant enzymes at this position (K108M, K108A, K108L). The results showed that Thr and Ser could replace Lys108 but resulted in only 2-20% of the activity of the native enzyme depending on the substrates used.

Enzymatic properties of mutant forms of RNase Rh from Rhizopus niveus as to Asp51

In order to determine the role of Asp51 of RNase Rh from Rhizopus niveus, enzymes with mutations at the 51st position, D51N, D51E, D51Q, D51S, D51T, D51A, and D51K, were prepared, and their enzymatic properties were investigated as to specific activity and base specificity. All the mutant enzymes showed relatively high activity toward poly I and poly C, and markedly reduced activity toward poly A and poly U. In particular, the enzymatic activities toward poly I of D51T and D51S were higher than that of RNase RNAP Rh. Among the mutant enzymes, D51N, D51S, and D51T showed more than ca. 30% of the activity of RNase Rh, when RNA, poly I and poly C were used as substrates, respectively. The substitution of Ala, Glu, or Lys at Asp51 is unfavorable for enzymatic activity. Among XpGs (X = A, G, U, or C), D51N, D51S, and D51T showed higher activity toward GpG then CpG. Therefore, Asp51 in RNase Rh plays a critical role in the adenylic acid preference of RNase T2 family enzymes. Our results obtained with a protein engineering technique provide basic insights into the control of the base specificity of RNase Rh.

Effects of human diets of two different Japanese populations on cancer incidence in rat hepatic drug-metabolizing and antioxidant enzyme systems

Hepatic enzyme systems of drug metabolism and antioxidation were investigated in rats fed the complete human diets consumed in the two Japanese prefectures, Akita and Okinawa, where the incidence of cancers was quite different: Okinawa had the lowest and Akita the highest age-adjusted mortality rate. In rats fed the human diet consumed in Okinawa, hepatic glutathione S-transferase activity was higher and lipid peroxide content was lower than in rats fed the diet consumed in Akita. These data might indicate that the number and/or quantity of the dietary components attributed to the detoxification of carcinogens and the scavenging reactive carcinogen species was much higher in the foods consumed in the population having lower cancer mortality rate.

Enzymatic properties of mutant enzymes at Trp49 and Tyr57 of RNase Rh from Rhizopus niveus

In order to establish the role of Tyr57 and Trp49 in the enzymatic reaction of RNase Rh, several mutant enzymes at Tyr57 and Trp49 were prepared by protein engineering and their enzymatic properties were investigated. Among the four mutant enzymes at Trp49 (W49F, W49Y, W49A, and W49I), W49F showed 16% of the activity of the native enzyme, but the others (W49Y, W49A, and W49I) showed greatly decreased activity. The data showed that Trp49 is very important for the enzyme activity. Among 8 mutant enzymes at the 57th position, Y57F and Y57W showed similar enzymatic activity toward RNA to that of the wild-type enzyme, but the others (Y57G, Y57A, Y57V, Y57M, and Y57K) are more active toward RNA and less active toward XpGs. The reason for the apparent increase for RNA activity is discussed from the view point of substrate inhibition. It is noteworthy that W49F and Y57W became more pyrimidine base- and purine base-preferential, respectively.

Base non-specific acid ribonuclease from Irpex lacteus, primary structure and phylogenetic relationships in RNase T2 family enzyme

Two base non-specific acid RNases (RNase Irp1 and RNase Irp2) were purified from a commercial enzyme, "Driselase" (Irpex lacteus) in a homogenous state on SDS-PAGE by several steps of chromatographic separations. RNAse Irp2 was a simple polypeptide with 235 amino acid residues and RNase Irp1 was a glycopeptide with 248 amino acid residues. The amino acid sequences of both RNases were identified by Edman degradation of the peptides derived from these RNAses. RNase Irp1 was composed of the RNase Irp2 and extra C-terminal 13 residues of peptide. The phylogenetic relation of these RNases with the other fungal RNases already known was discussed. The sequence of RNase Irp2 was very highly homologous (67.5%) with that of RNase Le2 from Lentinus edodes.

In vitro mRNA synthesis by Sendai virus: isolation and characterization of the transcription initiation complex

We have developed an in vitro transcription system using purified Sendai virus particles in which viral mRNA synthesis is almost entirely dependent on the addition of cellular proteins (host factors), one of which can be replaced by highly purified cellular tubulin [Mizumoto et al. (1995) J. Biochem. 117, 527-534]. In this study, to elucidate the function of host factors in transcription, we isolated an active initiation complex as a viral ribonucleoprotein, by incubating virus particles with bovine brain extract in the absence of nucleoside triphosphates, followed by ultracentrifugation. RNA products from the isolated initiation complex contained six mRNA species corresponding to all the virus-encoded genes, and most of them had a 5'-cap structure as well as a 3'-poly(A) tail. Immunoblotting showed that tubulin was specifically associated in the active complex. These data suggest that cellular tubulin, one of the host factors essential for Sendai virus transcription, interacts with the viral ribonucleoprotein to form an active complex at the initiation step.