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PubMed1994

Effect of zinc-chelating dipeptide on bone metabolism in weanling rats: comparison with beta-alanyl-L-histidinato zinc-related compounds.

Rats were orally administered zinc sulfate, di(histidino)-zinc (HZ), beta-alanyl-L-histidinato zinc (AHZ), and di(N-acetyl-L-alanyl-L-histidinato)-zinc (AAHZ) with the doses of 2.75 and 5.50 mg Zn/kg/day for 7 days, and 24 h later they were killed. With the dose of 2.75 mg Zn/kg/day, the administration of AHZ caused a significant increase of zinc content in the femoral diaphysis and a corresponding elevation of alkaline phosphatase activity, deoxyribonucleic acid (DNA), and calcium contents, but similar doses of zinc sulfate, HZ, and AAHZ did not have an appreciable effect on the enzyme activity and DNA content. Moreover, the dose of 5.50 mg Zn/kg/day with AHZ and AAHZ caused an appreciable increase in all zinc compounds observed, whereas zinc sulfate did not have the effect on bone DNA content and HZ had no effect on bone alkaline phosphatase activity. Of the various zinc-chelating dipeptides used, AHZ had a characteristic effect on bone metabolism in weanling rats. Thus, AHZ may have a pharmacological role.

Animals↗
PubMed1994

Effect of zinc-chelating dipeptides on osteoblastic MC3T3-E1 cells: activation of aminoacyl-tRNA synthetase.

The effect of zinc-chelating dipeptides on osteoblastic MC3T3-E1 cells was investigated. As zinc compounds, we used zinc sulfate, AHZ, di(N-acetyl-beta-alanyl-L-histidinato)zinc (AAHZ), and di(histidino)zinc (HZ). Cells were cultured for 72 h in the presence of zinc compounds (10(-8)-10(-5) M). The effect of AHZ (10(-7) and 10(-6) M) to increase protein and deoxyribonucleic acid (DNA) contents in the cells was the greatest in comparison with those of other zinc compounds. Zinc sulfate and HZ at 10(-7) M did not have an effect on the cellular protein content. AHZ (10(-6) M) had a potent effect on cell proliferation, although zinc sulfate (10(-6) M) had no effect. beta-Alanyl-L-histidine (10(-6) and 10(-5) M) did not have an appreciable effect on the cells. Those effects of AHZ (10(-6) M) on osteoblastic cells were completely abolished by the presence of cycloheximide (10(-6) M). AHZ (10(-8)-10(-5) M) directly activated [3H]leucyl-tRNA synthetase in the cell homogenate, whereas the effect of zinc sulfate was seen at 10(-6) and 10(-5) M. The present study suggests that the chemical form of zinc-chelating beta-alanyl-L-histidine (AHZ) can reveal a potent anabolic effect on osteoblastic cells, and that AHZ directly stimulates protein synthesis.

3T3 Cells↗
PubMed1995

Differential effects of transforming growth factor-beta on osteoclast-like cell formation in mouse marrow culture: relation to the effect of zinc-chelating dipeptides.

The effect of transforming growth factor-beta (TGF-beta) on osteoclast-like cell formation in mouse marrow culture in vitro was investigated. The bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone resorbing agent. Osteoclast-like cell formation was estimated with staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of TGF-beta (10(-13)-10(-11) M) caused a significant increase in the number of osteoclast-like multinucleated cells (MNCs); the maximum effect was seen with 10(-12) MTGF-beta. With a higher concentration (10(-10) M) of TGF-beta, the growth factor dramatically inhibited the 1,25-dihydroxyvitamin D5 [1,25(OH)2D3; 10(-8) M]-induced formation of osteoclast-like MNCs. This inhibitory effect was also seen in the formation of osteoclast-like MNCs stimulated by parathyroid hormone (10(-8) M), prostaglandine E2 (10(-6) M), and interleukin-1 alpha (50 U/ml). The stimulatory effect of TGF-beta (10(-12) M) on osteoclast-like MNCs formation was inhibited by zinc sulfate (10(-6) M) or zinc-chelating dipeptide [beta-alanyl-L-histidinato zinc (AHZ), 10(-6) M]. The stimulating effect of TGF-beta was markedly weakened by the presence of EGTA (0.5 mM), a chelator of Ca2+. The inhibitory effect of zinc compounds was not seen in the presence of EGTA. Moreover, the inhibitory effect of TGF-beta (10(-10) M), zinc sulfate (10(-6) M), or AHZ (10(-6) M) on osteoclast-like MNCs formation was not demonstrated in mature osteoclastic cells, although calcitonin (3 x 10(-8) M) significantly inhibited the osteoclastic formation. The present study demonstrates that TGF-beta has a stimulating and an inhibiting effect on osteoclast-like cell formation in mouse marrow culture, and that zinc can inhibit the stimulatory effect of TGF-beta.

Animals↗
PubMed1988

Utilization of dipeptides by Lactococcus lactis ssp. cremoris.

Different strains of Lactococcus lactis ssp. cremoris hydrolyze peptides at different rates while the cell-free extracts of these strains all show the same or much higher rates of hydrolysis. These observations indicate that the uptake of peptides is the rate-limiting step in peptide hydrolysis. Utilization of leucyl-leucine by non-growing cells is competitively inhibited by the structurally related dipeptide alanyl-alanine. After hydrolysis of peptides, the amino acids are released into the medium and only a small fraction is accumulated and/or incorporated. This hydrolysis is independent of the synthesis of proteases indicating that the synthesis of proteases and peptidases are regulated differently. The specific growth rate of L. lactis ssp. cremoris E8 depends upon the amino acid source in the medium. No significant differences have been observed in the intracellular peptidase activities and the rates of peptide uptake between L. lactis ssp. cremoris E8 cells grown in different media, indicating that this growth rate is determined by the availability of amino acids in free amino acids or peptides.

Chromatography, High Pressure Liquid↗
PubMed1994

The solubilities of five cyclic dipeptides in water and in aqueous urea at 298.15 K: a quantitative model for the denaturation of proteins in aqueous urea solutions.

The solubilities of cyclo(L-alanylglycine), cyclo(L-alanyl-L-alanine), cyclo(glycyl-L-leucine), cyclo(L-valyl-L-valine) and cyclo(glycyl-L-phenylalanine) were determined in water and in aqueous urea solutions up to concentrations of 9 molar urea at 298.15 K. The solubilities of all cyclic dipeptides increase with increasing urea concentration. A simple equilibrium model, taking into account the activity of urea and that of water, fits the solubility data yielding apparent equilibrium constants describing the interactions occurring between urea and the peptide groups plus the alkyl groups that are next to these peptide groups. The apparent equilibrium constants were converted to Gibbs energy parameters for each amino acid residue which were then used to make a quantitative estimate of the contribution of urea to the denaturation of proteins.

Chemical Phenomena↗
PubMed1984

Glutamate-containing dipeptides enhance specific binding at glutamate receptors and inhibit specific binding at kainate receptors in rat brain.

The dipeptide, L-phenylalanyl-L-glutamate (PG), augments the specific binding of the excitatory amino acid receptor antagonist, [3H]2-amino-7-phosphonoheptanoic acid (APH), to rat forebrain membranes by 5-fold at 100 microM with an EC50 of 4.9 microM. The increase in the specific binding of [3H]AHP induced by PG results exclusively from an increase in Bmax. In contrast, PG inhibits the specific binding of [3H]kainic acid to forebrain membranes with a Ki of 6.8 microM. Of several related peptides examined, active ones affected the two receptor sites in a reciprocal fashion. The results suggest an allosteric interaction between [3H]APH and kainate receptors modulated by glutamate-containing peptides.

2-Amino-5-phosphonovalerate↗
PubMed1984

Suppression of audiogenic seizures in DBA/2 mice by two new dipeptide NMDA receptor antagonists.

Two new phosphonate dipeptides, gamma-D- glutamylaminomethylphosphonate (Glu-Amp) and beta-D- aspartylaminomethylphosphonate (Asp-Amp), that are antagonists of excitation due to N-methyl-D-aspartate have been compared with omega-phosphonic-alpha-carboxylic amino acids as anticonvulsant agents in mice with sound-induced seizures. Compounds were injected intracerebroventricularly (i.c.v.) or intraperitoneally (i.p.) into DBA/2 mice 45 min prior to sound exposure, and ED50 values for suppression of the different phases of the seizure response were estimated. With i.c.v. injection Glu-Amp is 0.4-0.8 times as potent an anticonvulsant as (+/-)2-amino-7- phosphonoheptanoate and Asp-Amp is 1.3-2.5 times as potent. With i.p. injection Glu-Amp is 0.15-0.28 and Asp-Amp 0.23-0.58 times as potent as (+/-)2-amino-7-phosphonoheptanoic acid. These findings correspond to their known potency as N-methyl-D-aspartate antagonists, and are consistent with an anticonvulsant effect arising from action at a receptor sensitive to N-methyl-D-aspartate.

2-Amino-5-phosphonovalerate↗
PubMed1984

Phosphono dipeptides and piperazine derivatives as antagonists of amino acid-induced and synaptic excitation in mammalian and amphibian spinal cord.

Two novel dipeptides, beta-D-aspartylaminomethylphosphonate (Asp-AMP) and gamma-D-glutamylaminomethylphosphonate (Glu-AMP) are potent and selective N-methyl-D-aspartate receptor antagonists and specifically depress polysynaptic excitation in the cat, rat and frog spinal cords. In the same tissues, 1-(p-chlorobenzoyl)-piperazine-2,3-dicarboxylic acid (pCB-PzDA) and some related piperazines, are broader spectrum excitatory amino acid antagonists, showing increased potency as kainate and quisqualate antagonists compared with previously described antagonists of this type. These piperazines are more effective as depressants of monosynaptic than of polysynaptic excitation.

Amino Acids↗
PubMed1992

Modulation of glutamate agonist-induced influx of calcium into neurons by gamma-L-glutamyl and beta-L-aspartyl dipeptides.

Gamma-L-Glutamate and beta-L-aspartate dipeptides, present in the mammalian brain with a yet unknown function, were shown to affect the influx of Ca2+ into cultured cerebellar granule cells. The most active peptides, gamma-L-glutamyl-L-aspartate, gamma-L-glutamyl-L-glutamate and gamma-L-glutamylglycine, enhanced the basal influx but inhibited the glutamate-activated influx of Ca2+ in a dose-dependent manner. Gamma-L-Glutamyl-L-aspartate, the strongest inhibitor of the glutamate-activated influx of Ca2+, exhibited selective Mg(2+)-dependent antagonism in the N-methyl-D-aspartate (NMDA)-activated influx of Ca2+. This finding may explain its previously shown deleterious effects on the long-term memory. On the other hand, gamma-L-glutamyl-L-aspartate enhanced alone the entry of Ca2+ into neurons. This effect was antagonized by the non-NMDA antagonists 6-nitro-7-cyanoquinoxaline-2,3-dione (CNQX) and 6,7-dinitroquinoxaline-2,3-dione (DNQX), suggesting a non-NMDA receptor-mediated action, that may also be involved in excitotoxicity in some neurodegenerative disorders.

Animals↗
PubMed1993

Effects of intrathecal FK888, a novel dipeptide NK1 receptor antagonist, on the formalin test in the rat.

This study investigates the effects of intrathecally administered FK888, a novel dipeptide NK1 receptor antagonist, on the formalin test in the rat. Subcutaneous formalin induces biphasic episodes of flinching behavior at 0-5 min (Phase 1) and 10-60 min (Phase 2) after treatment. FK888 administered intrathecally 10 min before the formalin injection depresses the Phase 2 flinching behavior in a dose-dependent manner, but not the Phase 1 flinching behavior. FK888 has no effect on the Phase 2 flinching behavior when administered intrathecally 60 min before or 9 min after the formalin injection. Intrathecally administered FK888 has no effect on the motor function. These results suggest that FK888 is good drug to study the role of the NK1 receptor in the spinal cord of the rat.

Animals↗
PubMed1993

Gamma-L-glutamyl-L-glutamate is an endogenous dipeptide in the rat olfactory bulb which activates N-methyl-D-aspartate receptors.

The concentration of gamma-L-glutamyl-L-glutamate (gamma-glu-glu), a potent displacer of excitatory amino acid receptor binding, and other structurally related dipeptides were determined in extracts of the rat olfactory bulb by a novel liquid chromatographic method. Whole-cell patch clamp recordings of currents from freshly isolated neurons showed that gamma-glu-glu produced inward currents at negative holding potentials, provided microM concentrations of glycine were added and no Mg(2+)-ions were present, indicating activation of N-methyl-D-aspartate receptors. Consistently, geometry optimization of gamma-glu-glu using molecular mechanics calculations, suggested a bent conformer with structural features supporting this view.

Animals↗
PubMed1986

Rapid affinity chromatographic purification of human lung and kidney angiotensin-converting enzyme with the novel N-carboxyalkyl dipeptide inhibitor N-[1(S)-carboxy-5-aminopentyl]glycylglycine.

Human angiotensin-converting enzyme has been purified, in a single chromatographic step, using a novel N-carboxyalkyl dipeptide CA-GlyGly (N-[1(S)-carboxy-5-aminopentyl]glycylglycine) synthesised in our laboratory. CA-GlyGly is a weak competitive inhibitor, Ki = 0.18 mM, and its inhibitory profile is markedly pH-dependent. Human lung and kidney angiotensin-converting enzyme were solubilised with Triton X-100 and after ammonium sulphate fractionation the crude extract was applied to a column containing CA-GlyGly coupled to agarose via a 2.8 nm spacer group. Electrophoretically pure human angiotensin-converting enzyme could be eluted by raising the pH of the chromatography buffer from 7.50 to 9.50. The specific activity of human angiotensin-converting enzyme purified from lung was 104 units/mg, while that from kidney was 88 units/mg. Molecular weight for both enzymes was estimated to be 160,000. The Km with respect to hippuryl-L-histidyl-L-leucine was 1.9 mM in the case of lung angiotensin-converting enzyme and 1.7 mM in that of kidney angiotensin-converting enzyme, while for the substrate angiotensin I Km values were 62 microM and 76 microM, respectively. Hydrolysis of either substrate was chloride-dependent and both enzymes were strongly inhibited by captopril.

Angiotensin I↗
PubMed1989

Effects of L-1-methyl-histidine and the muscle dipeptides carnosine and anserine on the activities of muscle calpains.

1. Carnosine, anserine and L-1-methyl-histidine activated muscle calpain II assayed at 2.5 mM Ca2+. 2. At 5 microM Ca2+, none of these compounds activated calpain II sufficiently to bring its activity up to the level measured at 2.5 mM Ca2+. 3. Carnosine increased, whereas both anserine and L-1-methyl-histidine decreased the inhibitory effect of calpastatin on calpain II. 4. These results suggest that although the compounds are not potent activators of calpain II, the ratio of the dipeptides in muscle may have an effect on calpain II-calpastatin interaction.

Alanine↗
PubMed1986

Synthesis of carbon-11 labelled glycine and the dipeptides L-phenylalanylglycine and L-leucylglycine.

Carbon-11 labelled glycine has been prepared in 30 min by carboxylation of alpha-lithiomethylisocyanide with a radiochemical yield of 10-15%. After coupling with L-phenylalanine-N-carboxyanhydride and L-leucine-N-carboxyanhydride followed by HPLC purification, the corresponding dipeptides were obtained in 20 min with a radiochemical yield of 30-40%. Consequently, starting with 11CO2, non carrier added L-phenylalanyl[1-(11)C]glycine and L-leucyl-[1-(11)C]glycine in 0.1 N NaH2PO4 were obtained in 50 min with a radiochemical yield of 3-6%. The radiochemical yield figures are not corrected for decay.

Carbon Isotopes↗
PubMed1996

A solution-phase strategy for the synthesis of chemical libraries containing small organic molecules: a universal and dipeptide mimetic template.

A general approach to the solution phase, parallel synthesis of chemical libraries, which allows the preparation of multi-milligram quantities of each individual member, is exemplified with both a universal and dipeptide mimetic template. In each step of the sequence, the reactants, unreacted starting material, reagents and their byproducts are removed by simple liquid/ liquid or liquid/solid extractions providing the desired intermediates and final compounds in high purities (> or = 90-100%) independent of the reaction yields and without deliberate reaction optimization.

Dipeptides↗
PubMed2005

The inactivation of bovine cathepsin B by novel N-chloro-acetyl-dipeptides: application of the Houghten 'tea bag' methodology to inhibitor synthesis.

In this study, a series of N-chloro-acetylated dipeptides were synthesised by the application of Houghten's methodology of multiple analog peptide syntheses (MAPS). The peptides, all of which contain a C-terminal free acid, were tested as inactivators of bovine cathepsin B, in an attempt at exploiting the known and, amongst the cysteine proteinases, unique carboxy dipeptidyl peptidase activity of the protease. We have succeeded in obtaining a number of effective inactivators, the most potent of which-chloroacetyl-Leu-Leu-OH, inactivates the enzyme with an apparent second-order rate constant of 3.8 x 10(4)M(-1)min(-1). In contrast, the esterified analog, chloroacetyl-Leu-Leu-OMe, inactivates the enzyme some three orders of magnitude less efficiently, lending credence to our thesis that a free carboxylic acid moiety is an important determinant for inhibitor effectiveness. This preliminary study has highlighted a number of interesting features about the specificity requirements of the bovine proteinase and we believe that our approach has great potential for the rapid delineation of the subsite specificities of cathepsin B-like proteases from various species.

Acetylation↗
PubMed2006

Dipeptide proline diphenyl phosphonates are potent, irreversible inhibitors of seprase (FAPalpha).

Dipeptidyl peptidase IV (DPP-IV) and seprase belong to a small group of membrane-bound, proline-specific serine proteases, the serine integral membrane proteases (SIMPs). Whilst DPP-IV is the most exhaustively studied peptidase in this class, relatively less is known about the inhibitor/substrate specificity of its close homolog seprase. Additionally, whereas, DPP-IV expression is largely ubiquitous, seprase expression is restricted to tumour and tissue remodelling sites in vivo. Consequently, the highly restricted expression and distribution of seprase potentially make it an excellent therapeutic target for the modulation of neoplastic invasion and metastasis. Against this background, we now wish to report on the design, synthesis, and kinetic testing of a series of dipeptide proline diphenyl phosphonates, against DPP-IV and seprase. The most potent inhibitor of DPP-IV and seprase was found to be Gly-ProP(OPh)2, which exhibited overall second-order rate constants of inactivation of 5.24 x 105 M-1 min-1 and 1.06 x 104 M-1 min-1 against DPP-IV and seprase, respectively. Both proteases displayed differing profiles of susceptibility towards the other members of the series of inhibitors synthesised. In addition, Gly-ProP(OPh)2 and Tyr-ProP(OPh)2 were found to exert a considerable, dose-dependent anti-invasive effect on the LOX melanoma cell line, in vitro.

Animals↗
PubMed2006

Synthesis, structure, and hydrolytic reaction of trans-dichlorobis(diethanolamine-N)palladium(II) with N-acetylated L-histidylglycine dipeptide.

The reaction of PdCl2, or K2PdCl4, with diethanolamine (DEA), in the molar ratio 1:2, affords the trans-[PdCl2(DEA)2] complex. X-ray structure analysis of this complex confirmed the formation of the trans-isomer. The complex crystallizes in the space group P42bc. The central Pd(II) ion is coordinated in an almost ideal square-planar fashion with a small deformation of the Cl-Pd-Cl angle (175.6(7) degrees) due to N-H...Cl hydrogen bonding. The N-H group participates in a bifurcated interaction with the two symmetry related Cl- anions. The hydroxyl groups of the diethanolamine ligand form very strong hydrogen bonds between the complex units, thus leading to infinite zigzag (O-H...O-H...O-H..) chains in the crystal packing. The complex units are further connected by weaker intermolecular hydrogen bonds of the N-H...Cl type in a way to form layers parallel to the crystallographic (001) plane. The reaction between the trans-[PdCl2(DEA)2] or trans-[Pd(H2O)2(DEA)2]2+ complex and MeCOHis-Gly dipeptide at 1.5 < pH < 2.0 and at 25 degrees C leads to the regioselective cleavage of the amide bond involving the carboxylic group of the histidine. The cleavage of the substrate was fast and went almost to completion within less than one hour.

Catalysis↗