Regiospecificity of Immobilized Candida antarctica Lipase B (CAL-B) towards 2,3-Diacyl-1-O-alkyl Glyceryl Ether in Ethanol

Highly pure 2,3-dioleoyl-1-O-alkyl glyceryl ether (DOGE), whose 1-position is a lipase-tolerant ether bond, was chemically synthesized and its detailed regioselectivity and acyl transfer were confirmed. During ethanolysis using immobilized Candida antarctica lipase B (CAL-B) with DOGE as the substrate, monooleoyl-1-O-alkyl glyceryl ethers (MOGEs) and a few 1-alkyl glyceryl ethers were formed upon consumption of the substrate. The structure of MOGE was confirmed using nuclear magnetic resonance spectroscopy and only the isomer of 2-MOGE was formed, indicating that CAL-B has complete α- regiospecificity. During ethanolysis, 3-MOGE was formed via acyl migration. These results indicate that the formation of 1-alkyl glyceryl ethers is not due to the imperfect regiospecificity of CAL-B, but rather due to ethanolysis of the formed 3-MOGE. The ethanolysis rate at the 3-α-position of DOGE was faster and the rate of acyl transfer was slightly slower for chain lengths greater than 14. These results show for the first time that both deacylation at the 3-position and acyl migration from the 2- to 3-position are affected by the structure of 1-position.

DBU-intercalated γ-titanium phosphate as a latent thermal catalyst in the reaction of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA)

The capabilities and performance of γ-titanium phosphate (γ-TiP) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a latent thermal catalyst were investigated by the copolymerization of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA) at different temperatures for a period of one hour. Polymerization was not observed until the reactants were heated to 100 °C. Upon increasing the temperature to 120 °C, the conversion in the presence of γ-TiP·DBU as a catalyst showed 98% conversion in 1 h. The thermal stability of GPE and MHHPA reacted in the presence of γ-TiP·DBU at 40 °C for 144 h resulted in less than 7% conversion of GPE. The conversion of GPE did not show a significant increase at 40 °C.

Oriented growth of stacking α-cobalt hydroxide salt continuous films and their topotactic-like transformation to oriented mesoporous films of Co3O4 and CoO

Mesoporous metal oxide films composed of nanocrystal assemblies with an aligned crystallographic orientation are key nanostructures for efficient interfacial reactions; however, the development of a simple and versatile method for their formation on substrates still constitutes a challenge. Here we report the template-free centimetre-scale formation of novel cobalt oxide films of Co₃O₄ and CoO with a [111]-oriented mesoporous structure starting from stacking cobalt hydroxide continuous films. The cobalt hydroxide precursor is formed electrochemically on conductive substrates from a Co(NO₃)₂ aqueous solution at room temperature. A thorough characterization by means of scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis-NIR spectroscopy, IR spectroscopy and Raman spectroscopy analyses reveals that the precursor film is an α-type layered cobalt hydroxide salt (α-Co-LHS) containing interlayer nitrate and hydrated water, i.e., α-Co(OH) _x (NO₃) _y ·nH₂O, with a [001]-oriented stacking film structure. Heat treatment of the [001]-α-Co-LHS films using different conditions, i.e., under air at 550 °C or under vacuum at 500 °C, results in the selective formation of Co₃O₄ or CoO mesoporous films, respectively. A plausible explanation for the observed centimetre-scale topotactic-like transformation from α-Co-LHS[001] to Co₃O₄[111] or CoO[111] is given according to the atomic framework similarity between the hydroxide precursor and the final oxides.

Photo/Thermo Dual Stimulus-Responsive Liquid Marbles Stabilized with Polypyrrole-Coated Stearic Acid Particles

In this study, we report on the fabrication of photo/thermo dual stimulus-responsive liquid marbles (LMs) that can be disrupted by light irradiation and/or heating. To stabilize the LMs, we synthesized micrometer-sized stearic acid (SA) particles coated with overlayers of polypyrrole (PPy) by aqueous chemical oxidative seeded dispersion polymerization. The SA/PPy core-shell particles could adsorb at the air-water interface to stabilize LMs by rolling water droplets on the particle powder bed. The presence of SA, known as a phase-change material, which undergoes a transition from solid to liquid by heating, and PPy, which can transduce light to heat, gives rise to the photo and thermo dual stimulus-responsive characters of the LMs. The disruption of the LMs could be induced in a cascade manner: light irradiation on the LM induced a temperature increase, followed by melting of the SA component on the LM surface, leading to its disruption and release of the inner water. The disruption time is linked to the PPy loading and light irradiation power, and it can be tuned from quasi-instantaneous to a few tens of seconds. The melting of SA due to a light-induced phase change from the solid to liquid state is a new mechanism to trigger the disruption of LMs. We finally demonstrated two applications of the LMs as a light-responsive microreactor and a sensor.

Zeolitic Imidazolate Frameworks as Latent Thermal Initiators in the Curing of Epoxy Resin

The curing of a mixture of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA) with zeolitic imidazolate frameworks (ZIFs)-ZIF-7, ZIF-8, ZIF-11, and ZIF-14-as latent thermal initiators has been critically evaluated. For ZIF-8 and ZIF-14, the % conversion values for GPE were 92 and 93%, respectively, for curing at 100 °C and for 1 h. With regard to the stability of ZIF-8 and ZIF-14 in the GPE-MHHPA mixture, the % conversion values for GPE were 11 and 12% for storage over 8 days at 25 °C. The ZIF-8 and ZIF-14 initiators exhibited excellent thermal latency for heating at 100 °C and showed good stability for storage at 25 °C. To evaluate the practicality of the resin curing system, the reactions of 2,2-bis(4-glycidyloxyphenyl)propane (DGEBA) and MHHPA with ZIFs were studied by differential scanning calorimetry. Prominent exothermic peaks for ZIF-8 and ZIF-14 were observed at 157 and 162 °C, respectively; by comparison, for the commercially available microencapsulated latent thermal initiators HX-3088 and HX-3722, the respective peak maxima were 177 and 181 °C, respectively. The exothermic peak maxima for ZIF-8 and ZIF-14 were lower than those for HX-3088 and HX-3722. The ZIF-8 and ZIF-14 initiators can be stored in precured epoxy resin at 25 °C and cured by lower temperatures compared with commercially-available initiators HX-3088 and HX-3722.

Suzuki–Miyaura Cross-Coupling Reaction with Potassium Aryltrifluoroborate in Pure Water Using Recyclable Nanoparticle Catalyst

This paper describes the Suzuki–Miyaura cross-coupling reaction of aryl bromides with potassium aryltrifluoroborates in water catalyzed by linear polystyrene-stabilized PdO nanoparticles (PS-PdONPs). The reaction of aryl bromides having electron-withdrawing groups or electron-donating groups took place smoothly to give the corresponding coupling product in high yields. The catalyst recycles five times without significant loss of catalytic activity although a little bit increase in size of PdNPs was observed after the reaction.

Mechanistic Study on Allylic Arylation in Water with Linear Polystyrene-Stabilized Pd and PdO Nanoparticles

The catalytic cycle of allylic arylation in water catalyzed by linear polystyrene-stabilized Pd or PdO nanoparticles (PS-PdNPs or PS-PdONPs) was investigated. Stoichiometric stepwise reactions indicated that the reaction did not proceed stepwise on the surface of the catalyst. In the case of the reaction with PS-PdNPs, the leached Pd species is the catalytically active species and the reaction takes place through a similar reaction pathway accepted in the case of a complex catalyst. In contrast, allylic arylation using PS-PdONPs as a catalyst occurs via a Pd(II) catalytic cycle.

Poly(tetrafluoroethylene)-Stabilized Metal Nanoparticles: Preparation and Evaluation of Catalytic Activity for Suzuki, Heck, and Arene Hydrogenation in Water

Poly(tetrafluoroethylene)-stabilized Pd nanoparticles (PTFE-PdNPs) were prepared in water with 4-methylphenylboronic acid as a reductant and characterized using powder X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Small PdNPs with a fairly uniform size were obtained in the presence of PTFE, whereas aggregation of palladium was observed in the absence of PTFE. PTFE-PdNPs showed high catalytic activity for the Suzuki coupling reaction in water and were reused without any loss of activity. No palladium species were observed by ICP-AES analysis in the reaction solution after the reaction, nor was any change in particle size observed after the recycle experiment. PTFE-PdNPs also exhibited excellent catalytic activity and reusability for the Heck reaction in water. Although palladium species were not detected in the reaction solution after the reaction, aggregates and smaller sizes of PdNPs were observed in the TEM image of the recovered catalyst. PTFE was also useful as the stabilizer of rhodium nanoparticles (RhNPs) prepared by reduction with NaBH4. PTFE-RhNPs showed high catalytic activity and reusability toward arene hydrogenation under mild conditions.

Synthesis and characterization of polypyrrole-palladium nanocomposite-coated latex particles and their use as a catalyst for Suzuki coupling reaction in aqueous media

Polypyrrole-palladium (PPy-Pd) nanocomposite was deposited in situ from aqueous solution onto micrometer-sized polystyrene (PS) latex particles. The PS seed particles and resulting composite particles were extensively characterized with respect to particle size and size distribution, morphology, surface/bulk chemical compositions, and conductivity. PPy-Pd nanocomposite loading onto the PS seed latex particles was systematically controlled over a wide range (10-60 wt %) by changing the weight ratio of the PS latex and PPy-Pd nanocomposite. Pd loading was also controlled between 6 and 33 wt %. The conductivity of pressed pellets increased with the PPy-Pd nanocomposite loading and four-point probe measurements indicated conductivities ranging from 3.0 x 10(-1) to 7.9 x 10(-6) S cm(-1). Hollow capsule and broken egg-shell morphologies were observed by scanning/transmission electron microscopy after extraction of the PS component from the composite particles, which confirmed a PS core and PPy-Pd nanocomposite shell morphology. X-ray diffraction confirmed that the production of elemental Pd and X-ray photoelectron spectroscopy indicated the existence of elemental Pd on the surface of the composite particles. Transmission electron microscopy confirmed that nanometer-sized Pd particles were distributed in the shell. The nanocomposite particles functioned as an efficient catalyst for Suzuki-type coupling reactions in aqueous media for the formation of carbon-carbon bonds.

“β-cis-SAr effect” on decarbonylation from α,β-unsaturated acyl and aroyl complexes

Lone pair of heteroatom located at the beta-cis position in alpha,beta-unsaturated acyl and aroyl group 10 metal complexes dramatically facilitated the stoichiometric and catalytic decarbonylation reactions.

Photo-and-thiol-driven trans insertion of phenylacetylene into H-Pt bonds

The photo-and-thiol-driven trans insertion of phenylacetylene into H-Pt bonds of Pt(X)(H)(PPh3)2 (X = SAr, Cl, Br, and I) took place to afford Pt[(Z)-C(H)=CH(Ph)](X)(PPh3)2 in good yields.

Functional consensus for mammalian osmotic response elements

The molecular mechanisms underlying adaptation to hyperosmotic stress through the accumulation of organic osmolytes are largely unknown. Yet, among organisms, this is an almost universal phenomenon. In mammals, the cells of the renal medulla are uniquely exposed to high and variable salt concentrations; in response, renal cells accumulate the osmolyte sorbitol through increased transcription of the aldose reductase (AR) gene. In cloning the rabbit AR gene, we found the first evidence of an osmotic response region in a eukaryotic gene. More recently, we functionally defined a minimal essential osmotic response element (ORE) having the sequence CGGAAAATCAC(C) (bp -1105 to -1094). In the present study, we systematically replaced each base with every other possible nucleotide and tested the resulting sequences individually in reporter gene constructs. Additionally, we categorized hyperosmotic response by electrophoretic mobility shift assays of a 17-bp sequence (-1108 to -1092) containing the native ORE as a probe against which the test constructs would compete for binding. In this manner, binding activity was assessed for the full range of osmotic responses obtained. Thus we have arrived at a functional consensus for the mammalian ORE, NGGAAAWDHMC(N). This finding should accelerate the discovery of genes previously unrecognized as being osmotically regulated.

Effects of hyperosmolality on Na, K-ATPase gene expression in vascular smooth muscle cells

Cultured vascular smooth muscle cells (VSMC) from rat thoracic aortas were exposed to hyperosmotic media to determine the effects on Na, K-ATPase alpha1- and beta1-mRNA expression. Hyperosmotic media (500 mOsm/kgH2O) supplemented with glucose or mannitol increased alpha1-mRNA levels threefold at 24 hr and beta1-mRNA levels sevenfold at 12 hr. In sharp contrast, hyperosmotic urea medium had no effect at any time. Both the protein synthesis inhibitor cycloheximide and the RNA transcription inhibitor actinomycin D reduced alpha1- and beta1-mRNA upregulation induced by hyperosmotic glucose or mannitol media. Protein kinase C (PKC) inhibitors (staurosporine A or calphostin C) or tyrosine kinase (TK) inhibitors (genistein or herbimycin A) had no effect on the alpha1-mRNA upregulation induced by hyperosmotic glucose or mannitol media. Hyperosmotic glucose or mannitol media (500 mOsm/kgH2O) significantly increased alpha1- and beta1-subunit protein levels and Na, K-ATPase activity, whereas hyperosmotic urea medium had no effect. Transfection experiments with the 5'-flanking sequences of the alpha1- or beta1-subunit genes linked to the luciferase reporter gene revealed that hyperosmolar glucose medium increased luciferase activity 2.9- and 3.7-fold, respectively. Similarly, hyperosmotic mannitol medium increased such activity 2.7- and 3.4-fold, respectively. These results demonstrate that: (i) hyperosmolality induced by the poorly permeating solutes (glucose and mannitol) stimulates alpha1- and beta1-mRNA accumulation, alpha1- and beta1-subunit protein accumulation, and Na, K-ATPase activity, whereas the rapidly permeating solute (urea) has no effect; (ii) the upregulation of alpha1- and beta1-mRNA in response to hyperosmotic glucose or mannitol media requires, at least in part, de novo synthesis of intermediate regulatory proteins; (iii) the hyperosmolality-induced alpha1-mRNA upregulation occurs through PKC- and TK-independent mechanisms, whereas the hyperosmolality-induced beta1-mRNA upregulation occurs through activation of PKC and TK; and (iv) hyperosmolality induced by glucose or mannitol increases promoter activities of the alpha1- and beta1-subunit genes.

Serum transcriptionally regulates Na(+)-K(+)-ATPase gene expression in vascular smooth muscle cells

The present study was designed to examine the effects of serum on Na(+)-K(+)-ATPase alpha 1- and beta 1-subunit gene expression in cultured vascular smooth muscle cells (VSMC) from rat thoracic aortas. Addition of 10% serum to VSMC for 24 h increased Na(+)-K(+)-ATPase activity 1.5-fold and alpha 1- and beta 1-subunit protein levels 1.9-fold. Serum (10%) caused a 3.5-fold increase in alpha 1-mRNA levels and a 6.7-fold increase in beta 1-mRNA levels, with peak elevations at 12 h. The protein synthesis inhibitor cycloheximide abolished serum-mediated beta 1-mRNA induction but did not affect serum-mediated alpha 1-mRNA induction. Protein kinase C (PKC) inhibitors (staurosporine A or calphostin C) or tyrosine kinase (TK) inhibitors (genistein or herbimycin A) significantly reduced serum-mediated beta 1-mRNA induction but had no effect on serum-mediated alpha 1-mRNA induction. Transfection experiments with the 5'-flanking sequences of the alpha 1- or beta 1-subunit genes linked to the luciferase reporter gene revealed that 10% serum caused 2.8- and 6.5-fold increases in luciferase activity, respectively. Among growth factors, only basic fibroblast growth factor (FGF) enhanced luciferase activities for the alpha 1- and beta 1-subunit genes. We conclude that 1) serum stimulates alpha 1- and beta 1-mRNA expression, alpha 1- and beta 1-subunit protein accumulation, and Na(+)-K(+)-ATPase activity; 2) serum-mediated beta 1-mRNA induction partly requires de novo synthesis of intermediate regulatory proteins and activation of PKC and TK, whereas serum-mediated alpha 1-mRNA induction occurs through PKC- and TK-independent mechanisms; 3) the 5'-flanking regions of the alpha 1- and beta 1-subunit genes are serum responsive; and 4) FGF mimics stimulatory effects of serum on promoter activities for the alpha 1- and beta 1-subunit genes.

Hyperosmolality stimulates Na-K-ATPase gene expression in inner medullary collecting duct cells

Primary cultures of inner medullary collecting duct (IMCD) cells of rats were incubated in hyperosmotic media to determine the effects on Na-K-ATPase alpha 1- and beta 1-subunit mRNA expression. Osmolality of the incubation media was raised from 300 up to 500 mosmol/kgH2O by adding NaCl, mannitol, raffinose, or urea. Hyperosmotic media supplemented with NaCl, mannitol, or raffinose caused two- to fourfold increases in the alpha 1-subunit mRNA accumulation and five- to eightfold increases in the beta 1-subunit mRNA accumulation, with peak elevations of both subunits at 12 h after addition. In sharp contrast, hyperosmolar urea medium had no effect at any time. When NaCl or mannitol was added to the media in amounts ranging from 300 to 600 mosmol/kgH2O, the maximal effects on both alpha 1- and beta 1-subunit mRNA accumulation occurred at 500 mosmol/kgH2O. In urea-supplemented medium, however, there was no significant change at any level of osmolality. The upregulation of alpha 1- and beta 1-subunit mRNA induced by hyperosmotic mannitol- or raffinose-supplemented media was markedly inhibited by removal of Na from the culture medium. Furthermore, pretreatment with a protein synthesis inhibitor cycloheximide partially inhibited the upregulation of alpha 1- and beta 1-subunit mRNA in IMCD cells exposed to hyperosmotic media treated with NaCl or mannitol. When IMCD cells were incubated with hyperosmotic media (500 mosmol/kgH2O) supplemented with NaCl or mannitol for 24 h, Na-K-ATPase activity increased by 78.6 and 82.8%, respectively. In contrast, hyperosmolar urea medium had no significant effect on Na-K-ATPase activity. These results demonstrate that 1) hyperosmolality induced by the poorly permeating solutes (NaCl, mannitol, and raffinose) but not the rapidly permeating solute (urea) stimulates both alpha 1- and beta 1-subunit mRNA accumulations in IMCD cells in a time- and an osmolality-dependent manner, 2) the hyperosmolality-induced upregulation of alpha 1- and beta 1-subunit mRNA leads to an increase in Na- K -ATPase activity; and 3) the above upregulation of alpha1- and beta 1-subunit mRNA in response to hyperosmotic media requires, at least in part, the presence of Na in the extracellular medium and the de novo synthesis of intermediate proteins.

Differential regulation of Na+-K+-ATPase gene expression by corticosteriods in vascular smooth muscle cells

To determine whether gluco- and mineralocorticoids have specific actions on Na+-K+-ATPase gene expression in vascular tissue, we used Northern blot analysis to compare the effects of dexamethasone (Dex) and aldosterone (Aldo) on Na+-K+-ATPase alpha1 and beta1-subunit mRNA expression in cultured vascular smooth muscle cells from rat aortae. Dex at 10(-6)M increased alpha1 -mRNA level 2.5-fold at 24 h and beta1-mRNA level 9.9-fold at 12 h. Aldo at 10(-6)M increased alpha1-mRNA 2.7-fold at 48 h and beta1-mRNA level 10.9-fold at 6 h. The half-maximal stimulation of both alpha1 and beta1-mRNA levels occurred at a concentration of 5-7 X 10(-9)M Dex, whereas it occurred at a concentration of 2-3 X 10(-9)M Aldo. The glucocorticoid receptor antagonist RU-38486 inhibited both Dex- and Aldo-mediated induction of beta1-mRNA. The mineralocorticoid receptor antagonist spironolactone inhibited Aldo-mediated induction of beta1-mRNA, whereas it had no effect on Dex-mediated induction of beta1-mRNA. Removal of Na+ from the extracellular medium (isosmotic replacement with choline) caused no effect on Dex-mediated induction beta1-mRNA, whereas it inhibited Aldo-mediated induction of beta1-mRNA. Addition of a specific inhibitor of the Na+/H+ exchange, ethylisopropylamiloride, had no effect on Dex-mediated induction of beta1-mRNA, whereas it resulted in a significant inhibition of Aldo-mediated induction of beta1-mRNA. We conclude that 1) both Dex and Aldo induce Na+-K+-ATPase alpha1- and beta1-mRNA expression in a time- and dose-dependent manner; 2) Dex-mediated induction of beta1-mRNA occurs only through glucocorticoid receptors, whereas Aldo-mediated induction of beta1-mRNA occurs through both gluco- and mineralocorticoid receptors; and 3) Dex-mediated induction of beta1-mRNA occurs through Na+-independent mechanisms, whereas Aldo-mediated induction of beta1-mRNA, at least in part, occurs through Na+-dependent mechanisms, including stimulation of the Na+/H+ exchange.

Pulmonary hypertension in systemic lupus erythematosus: a report of an autopsied case

An autopsied case of systemic lupus erythematosus with pulmonary hypertension is reported. A 29-year-old woman with a seven-year history of polyarthralgia, butterfly rash, nephrotic syndrome and Raynaud's phenomenon was admitted because of progressive dyspnea on exertion. Tests for antinuclear antibody, anti-cardiolipin antibody and lupus anticoagulant were positive. Echocardiographic examination revealed right ventricular hypertrophy and a moderate pericardial effusion. Estimated systolic pulmonary arterial pressure was 53 mmHg. Despite treatment with corticosteroids including pulse methylprednisolone therapy, lipo-PGE1 and warfarin, she died of progressive congestive heart failure. Postmortem examination of the pulmonary vasculature revealed findings consistent with plexogenic pulmonary arteriopathy, without evidence of vasculitis, fibrinoid necrosis, or thromboemboli.

[Severe bleeding in a case of factor VIII inhibitor associated with intravascular lymphomatosis]

A 70-year-old man was admitted to Jichi Medical School Hospital on October 1, 1990, complaining of spontaneous severe hemorrhage in his extremities. He had prolonged APTT value and normal PT value. Factor VIII level was markedly diminished, and a high titer of factor VIII inhibitor was observed. He was diagnosed as having idiopathic factor VIII inhibitor because of no sign of underlying disorders. He received prednisolone and immunosuppressants, subsequently with plasma exchange and bolous factor VIII, resulting in disappearance of the inhibitor. He was admitted again in February 1991, because of the reappearance of factor VIII inhibitor. In June, furthermore, bone marrow smears showed infiltration of atypical B cells, although no evidence of organomegaly and adenopathy was observed. Therefore, he was suspected to have primary bone marrow lymphoma. He received CHOP therapy, but he died of multiorgan failure. Postmortem autopsy demonstrated multifocal intravascular lymphomatosis with marked intravascular involvement of the lung, liver, kidney, adrenal glands, spleen and bone marrow. Lymph nodes were not swollen, showing little evidence of intravascular lymphomatosis.

Synthesis and characterization of the selenium analog of glutathione disulfide

We synthesized the selenium analog of glutathione disulfide by a liquid phase method and named it glutaselenone (i.e., gamma-L-glutamyl-L-selenocysteinylglycine) diselenide. The selenol of selenocysteine was protected by the p-methoxybenzyl group, which was removed by acidolysis with trifluoroacetic acid in the presence of thioanisol. The overall yield of the final product, glutaselenone diselenide, was about 9% based on the starting compound, Se-(p-methoxybenzyl)-L-selenocysteine. Glutaselenone diselenide showed a broad absorption band between 270 and 400 nm and circular dichroism bands around 270 nm (positive) and 330 nm (negative), which were attributable to diselenide bond.

Interaction of human parathyroid hormone-related peptide with parathyroid hormone receptors in clonal rat osteosarcoma cells

Synthetic peptides corresponding to the amino-terminal region of the human parathyroid hormone-related peptide (hPTHrp) were used to characterize the interaction of hPTHrp with parathyroid hormone (PTH) receptors in clonal rat osteosarcoma cells (ROS 17/2.8). Both hPTHrp-(1-34) and [Tyr40]hPTHrp-(1-40) showed full agonist activity in stimulating cyclic AMP accumulation in ROS cells; human PTHrp-(1-34) was approximately 2.5-fold as potent as hPTH-(1-34). Both [Tyr-40]hPTHrp-(3-40) and hPTH-(3-34) inhibited the cyclic AMP increase induced by either hPTHrp or PTH with parallel dose-inhibition curves. Binding to intact ROS cells of a 125I-labeled [Tyr40]hPTHrp-(1-40) (125I-[Tyr40]hPTHrp-(1-40)) which retains full biological activity was time- and temperature-dependent and reversible. Binding of 125I-[Tyr40]hPTHrp-(1-40) and 125I-labeled [Nle8, Nle18, Tyr34]bovine PTH-(1-34)NH2 to ROS cells was competed for, to the same extent and with the comparable potency, by either unlabeled hPTHrp or PTH peptides. The binding capacity and affinity of receptors in ROS cells were strikingly similar for hPTHrp and PTH. Affinity cross-linking with either radioligand resulted in high affinity, specific labeling of an apparently identical macromolecule centering at Mr = 80,000, which was detected in sodium dodecyl sulfate-polyacrylamide gel electrophoresis in both reducing and nonreducing conditions. The data indicate that hPTHrp and PTH, their amino-terminal fragments at least, interact with the identical receptors with regard to affinity, capacity, specificity, and physicochemical characteristics in osteoblastic ROS 17/2.8 cells.