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PubMed1985

Structure of alahopcin (nourseimycin), a new dipeptide antibiotic.

The structure of alahopcin (nourseimycin) (1), a new dipeptide antibiotic isolated from Streptomyces, has been established to be (2S, 3R)-2-[(L-alanyl)amino]-4-formyl-3-(hydroxy-aminocarbonyl)butyric acid. 1 exists in two cyclic hemiacetal type tautomers formed by intramolecular ring closure between the hydroxyamino group and the formyl group in aqueous solution. The structure of the new weakly acidic amino acid (2), a constituent of 1, is revealed to be (2S, 3R)-2-amino-4-formyl-3-(hydroxyaminocarbonyl)butyric acid, and 2 also exists in two cyclic hemiacetal type tautomers in aqueous solution.

Anti-Bacterial Agents↗
PubMed2000

Effective production of dehydro cyclic dipeptide albonoursin exhibiting pronuclear fusion inhibitory activity. II. Biosynthetic and bioconversion studies.

Albonoursin production was greatly enhanced when cyclo (L-Leu-L-Phe) (CFL), a tetrahydro derivative of albonoursin, was added to the 2-day culture of an albonoursin-producing actinomycete, Streptomyces albulus KO-23. The increase in albonoursin production paralleled the amount of CFL added. Furthermore, the resting cells of the strain catalyzed the bioconversion of CFL to albonoursin. The optimum pH and temperature for the conversion were found to be pH 10.0 and 50 degrees C. The feeding experiments and the resting-cell reactions revealed that albonoursin is biosynthesized by dehydrogenation of CFL in the actinomycete. This is the first report for a dehydrogenation of amino acid residues at the alpha,beta-positions in cyclic dipeptides.

Actinomycetales↗
PubMedDate not supplied

[Molecular dynamics of oligopeptides. 3. Maps of levels of free energy of modified dipeptides and dynamic correlation in amino acid residues].

A method of free energy maps for studying the dynamic correlations of fluctuations in molecules with conformational mobility is proposed. An agreement between the structure of the free energy level map and the type of the corresponding cross-correlation function (in the presence and absence of the correlation of fluctuations in conformational freedom degree in modified dipeptides) was established.

Amino Acids↗
PubMedDate not supplied

[Synthesis and study of biological activity of stereoisomeric dipeptides containing tyrosine and arginine residues].

Series of methyl esters of stereoisomeric dipeptides of the sequences Tyr-Arg and Arg-Tyr has been synthesized by classic methods of the peptide chemistry. The study of their reactivity towards thrombin and trypsin has shown that the kinetic parameters of enzyme-catalyzed hydrolyses of stereoisomeric compounds differ in values essentially. Testing the synthetic peptides on analgic effect, on inhibition of the reaction fibrinogen with thrombin or on influence upon the process of fibrin-monomer polymerization has shown that these biological effects depend on peptide structure and on configuration of amino acid residues forming the peptides.

Antithrombins↗
PubMed2000

Characterization of a murine gene encoding an acidic-basic dipeptide repeat that interacts with GADD34.

GADD34 is one of a subset of proteins induced after DNA damage or cell growth arrest. To examine the function of GADD34, we used the yeast two-hybrid system to clone the protein that interacts with murine GADD34. We utilized as bait the partial product of GADD34 cDNA including the PEST region and the gamma(1)34.5. One cDNA clone was almost the same as MuRED, which encodes an acidic-basic dipeptide repeat; we named it G34BP. The interaction between GADD34 and G34BP was also confirmed in the NIH3T3 cells by in vivo two-hybrid analysis. For the binding of two proteins, the PEST region was important, and the C-terminal of G34BP was necessary. G34BP was detected in all the mouse tissues examined. Although GADD34 was significantly elevated with methyl methanesulfonate treatment, G34BP expression was not induced. Overexpression of G34BP in the NIH3T3 cells inhibited the cell growth analyzed by WST1 assay.

3T3 Cells↗
PubMedDate not supplied

Interference of rheumatoid factor activity by aspartame, a dipeptide methyl ester.

Circulating autoimmune complexes of IgM rheumatoid factors (RF) bound to the Fc portions of normal, polyclonal IgG antibodies are frequently present in humans with rheumatoid arthritis (RA). The sweet tasting methyl ester of L-Asp-L-Phe (aspartame or APM) was found to relieve pain and improve joint mobility in subjects with osteo- and mixed osteo/rheumatoid arthritis [Edmundson, A. B. and Manion, C. V. (1998). Clin. Pharmac. Ther. 63, 580-593]. These clinical observations prompted the testing of the inhibition by APM of the binding interactions of human IgM RFs with IgG Fc regions. The propensity of APM to inhibit IgM RF binding was assessed by competitive enzyme immunoassays with solid-phase human IgG. Ten RA serum samples and three purified monoclonal cryoglobulins, all of which had RF activity, were tested in this system. We found that the presence of APM significantly reduced the binding of IgM RFs. The inhibitory propensity of APM with monoclonal RF cryoglobulins was increased by the addition of CaCl(2) to the binding buffer. Similar inhibition of the binding of RA derived RFs to IgG was observed for Asp-Phe and its amidated derivative, indicating that the methyl ester is not required for APM's interaction with IgM antibodies. A human (Mez) IgM known to bind octameric peptides derived from the Fc portion of a human IgG(1) antibody was tested for binding of dipeptides by the Pepscan method of combinatorial chemistry. The relative binding constants of Asp-Phe and Phe-Asp were ranked among the highest values for 400 possible combinations of the 20 most common amino acids. Possible blocking interactions of APM were explored by computer-assisted docking studies with the model of a complex of an RF Fab with the Fc of a human IgG(4) antibody. Modeling of ternary immune complexes revealed a few key residues, which could act as molecular recognition sites for APM. A structural hypothesis is presented to explain the observed interference with RF reactivity by APM. Extrapolations of the current results suggest that APM may inhibit the binding of IgG in a substantial proportion of IgM RFs. Interference of RF reactivity, especially in RA patients, may alleviate the pain and immobility resulting from chronic inflammation of the joints.

Adult↗
PubMedDate not supplied

[Statistical distribution of dipeptides in protein structures and dynamic characteristics of some protein fragments].

Statistical distributions of the occurrence of dipeptide fragments in proteins were studied. Various algorithms of ordering of files of frequency distribution were used. A correlation of occurrence of pairs of amino acid residues in various classes of proteins was established. The problem of the dynamic compatibility of amino acid residues in protein structures is discussed. The dynamic properties of frequently and seldom occurring dimers of amino acids are compared.

Amino Acid Sequence↗
PubMedDate not supplied

[Behavioral and electrophysiological analysis of the choline-positive effect of nootropic dipeptide acylproline (GVS-111)].

The behavioral experiments using a passive avoidance learning model showed that the new cognition-enhancing acyl-prolyn containing dipeptide GVS-111 promotes recovery of the test performance in animals with a long-term memory deficit caused by the M-cholinolytic scopolamine (1 mg/kg/day scopolamine for 20 days, followed by 0.5 mg/kg/day GVS-111 for 10 days). At the same time, GVS-111 increased the duration of tremor induced by the M-cholinomimetic arecoline. The results of electrophysicological experiments showed that GVS-111 in a concentration range from 10(-11) to 10(-9) M increased amplitude of the neural response to acetylcholine (Ach) microappications in 75% of the isolated neurons of Helix Pomatum and produced a predominantly facilitating effect upon the endoneuronal pacemaker activity. The effect of GVS-111 upon the Ach response in a part of neurons was attenuated or even blocked by scopolamine, and in the other neurons--by the N-cholinolytic d-tubocurarine. This fact indicates that both muscarinic and nicotinic receptors are involved in the mechanism of the cholino-sensitizing action of GVS-111 upon the neuronal activity.

Acetylcholine↗
PubMed2001

In vitro effects of isoprinosine and a dipeptide methyl ester on Echinococcus multilocularis protoscoleces.

A protoscoleces/vesicles in vitro maintenance test with assessment of viability by eosin exclusion was used to evaluate the quantitative and qualitative activities of isoprinosine, its active component inosine and the dipeptide methylester L-Phe-Phe-OMe on isolated protoscoleces of Echinococcus multilocularis for 24 and 48 h. Isoprinosine and inosine showed dose- and time-dependent activity, the latter displaying a more rapid effect than the former. A high activity was shown with L-Phe-Phe-OMe, when compared to praziquantel. Ultrastructural alterations were much more striking with L-Phe-Phe-OMe, with an effect similar to that of praziquantel, whereas the chemotherapeutic activity of inosine and isoprinosine appeared to be directed against a metabolic target, with a lethal effect not immediately visible at the ultrastructural level. Thus, the previously reported in vivo activities of these drugs result largely from a direct effect on the parasite.

Animals↗
PubMed1999

[Nutritional impact of glycyl-glutamine dipeptide on the autotransplanted small intestine in pig].

OBJECTIVE: To observe the impact of glycyl-glutamine (Gly-Gln) dipeptide on the autotransplanted small bowel. METHODS: Ten unbred pigs underwent small bowel autotransplantation and were divided randomly into two groups: GTPN and STPN. In the GTPN group (n = 5), the pigs received TPN supplemented with Gly-Gln for 28 days, whereas in the STPN group (n = 5), the pigs received isonitrogenous and isocaloric standard TPN for 28 days. The content of plasma glutamine (Gln), the concentrations of mucosal Gln, protein, villous DNA and RNA, villous height, mucosal thickness, crypt depth, villous surface area, D-xylose absorption test, and intestinal permeability to (99m)Tc-DTPA were measured on the operative day or on the 1st and 28th day after operation. RESULTS: All the indexes except the intestinal permeability (IP) to (99m)Tc-DTPA were significantly higher in the GTPN group than in the STPN group (P < 0.05) on the 28th day after operation, but the IP to (99m)Tc-DTPA was significantly lower in the GTPN group than in the STPN group (P < 0.05). CONCLUSIONS: Gly-Gln has special nutritional effect in improving the metabolism, structure and function of autotransplanted small intestine in pig.

Animals↗
PubMedDate not supplied

[Molecular dynamics of oligopeptides. 4. Dynamic characteristics of frequently and rarely occurring dipeptide fragments of proteins].

The existence of differences in the dynamic organization of frequently and the rarely occurring dipeptide fragments in globular and membrane proteins was shown. The dynamic isomorphism and the collective degrees of freedom in these fragments were analyzed. A topological classification of the maps of the levels of free energy for pairs of dihedral angles of the main chain and side residues was carried out.

Algorithms↗
PubMedDate not supplied

[Effect of the novel dipeptide nootropic agent noopept and its metabolite cyclo-L-prolylglycine on the transcallosal evoked potential in the rat brain].

The effect of new nootropic dipeptides--noopept (N-phenylacetyl-L-prolylglycine, GVS-111) and its metabolite (cyclo-L-prolylglycine)--and a standard nootrope piracetam on the transcallosal evoked potential (TEP) in rat brain was studied. In the dose range from 150 to 300 mg/kg, piracetam increased the TEP amplitude, which exhibited a maximum after 1.5-2 h and then gradually decreased. Both noopept and cyclo-L-prolylglycine also increased the TEP amplitude, which attained a plateau and retained this level over the entire observation time (above 3.5 h). All the nootropes studied increased both components of the evoked potential. Piracetam and cyclo-L-prolylglycine led to an approximately equal increase in both waves, while noopept induced a somewhat greater increase in the negative TEP wave amplitude. It is suggested that the positive effect of noopept and cyclo-L-prolylglycine upon the interhemispheric signal transfer (indicated by the improved transcallosal response) can be considered as a potential neurophysiological basis for a positive drug influence on the behavioral level.

Animals↗
PubMedDate not supplied

[Anti-inflammatory properties of noopept (dipeptide nootropic agent GVS-111)].

It is established that single intravenous (0.5 and 5 mg/kg, p.o.) or single peroral (10, 50, 100 mg/kg) and prolonged peroral (5 mg/kg, over 10 days) administration of noopept produces a dose-dependent inhibition of the model inflammatory response to concanavaline A in CBA mice. Intravenously injected (5 mg/kg) noopept suppressed the acute nonimmune carrageenan-induced foot inflammation in rats by 62.2% within 3 h. The most pronounced antiinflammatory effect of dipeptide was observed on the model of adjuvant arthritis in rats, where the drug administered over 25 days in a daily dose of 0.5 mg/kg (i.m.) or 5 mg/kg (p.o.) significantly reduced the chronic immune inflammation (on the 12th day, by 94.0 and 74.1%, respectively). The in vitro experiments with neutrophilic leukocytes of F1(CBA.C57BL/6) mice treated with noopept in a single dose of 5 mg/kg (i.v.) showed a 5- to 6-fold suppression of the hemiluminescence stimulated by opsoinized zymosan or phorbolmyristate acetate. It is suggested that the antiinflammatory activity of noopept is probably related to its antioxidant properties.

Animals↗
PubMed2002

Carnosine and related dipeptides protect human ceruloplasmin against peroxyl radical-mediated modification.

Ceruloplasmin (CP) is the major plasma antioxidant and copper transport protein. In a previous study, we showed that the aggregation of human ceruloplasmin was induced by peroxyl radicals. We investigated the effects of antioxidant dipeptides carnosine, homocarnosine and anserine on peroxyl radical-mediated ceruloplasmin modification. Carnosine, homocarnosine and anserine significantly inhibited the aggregation of CP induced by peroxyl radicals. When CP was incubated with peroxyl radicals in the presence of three compounds, ferroxidase activity, as measured by the activity staining method, was protected. All three compounds also inhibited the formation of dityrosine in peroxyl radicals-treated CP. The results suggest that carnosine and related compounds act as peroxyl radical scavenger to protect the protein modification. It is proposed that carnosine and related peptides might be explored as potential therapeutic agents for pathologies that involve CP modification mediated by peroxyl radicals generated in the lipid peroxidation.

Anserine↗
PubMedDate not supplied

[Intermolecular interactions of dipeptide triterpene derivatives and natural quinones with alpha-tocopherol].

In modeling system of the initiated oxidation of methyl oleate the antioxidation activity of a series of dipeptide derivatives of betulonic and glycyrrhetic acids, natural quinones (ubiquinone, philloquinone and menadione) and the kinetic effects of their combined action with alpha-tocopherol were studied. The same extreme character of the dependence of inhibitory action on the concentration of all investigated substances was found. Combined addition of triterpenoids or quinones together with alpha-tocopherol attenuated their effect. The mechanism of intermolecular interactions of tocopherol with quinones and triterpenoids is offered. The biological importance of these effects is discussed.

Antioxidants↗
PubMed2003

Synthesis of benzylamides of dipeptides as potential inhibitors of plasmin.

Four benzylamides of dipeptides with the general formula: X-L-Lys-NH-CH2-C6H5, where X = L-or D-Leu and L-or D-Phe were prepared as potential inhibitors of plasmin. All of them influenced on the fibrynolytic activity of plasmin, but only D-Leu-L-Lys-NH-CH2-C6H5 inhibited the amidolytic activity of this enzyme. None of the tested compounds was an inhibitor of thrombin in an amidolytic test.

Benzyl Compounds↗
PubMed2003

[Three cyclic dipeptides from the root of Psammosilene tunicoides].

OBJECTIVE: [corrected] To study the cyclic peptides from Psammosilene tunicoides. METHOD: The constituents were separated and purified with chromatographic methods, identified by NMR, MS, UV and IR. RESULT: Three cyclic dipeptides: cyclo(-Pro-Val-) (1), cyclo(-Pro-Ala-) (2) and cyclo(-Pro-Pro-) (3), were isolated and identified. CONCLUSION: Compound 1 and 2 are new natural products, compound 3 was isolated for the first time from Psammosilene tunicoides.

Caryophyllaceae↗
PubMedDate not supplied

Selected cyclic dipeptides inhibit cancer cell growth and induce apoptosis in HT-29 colon cancer cells.

BACKGROUND: An increasing number of cyclic dipeptides (CDPs), particularly those containing proline, have been shown to exhibit important biological activity. MATERIALS AND METHODS: We investigated the potential of seven proline-based CDPs to inhibit cancer cell growth in HT-29, HeLa and MCF-7 cell lines. We also tested whether any of the CDPs were able to induce apoptosis in HT-29 cells. RESULTS: The SRB assay showed that only cyclo(Phe-Pro) (10 mM) exhibited more than 50% growth inhibition (p<0.01). The MTT assay was used to demonstrate a dose-dependent (0.008-10 mM) growth inhibition by cyclo(Phe-Pro). Hoechst 33342 staining showed that 5 mM cyclo(Phe-Pro) induced chromatin condensation in 18.3+/-2.8% (p<0.01) of HT-29 cells after 72 hours. Furthermore, annexin V binding revealed phosphatidylserine externalisation in cyclo(Phe-Pro)-treated HT-29 cells. CONCLUSION: Our findings demonstrate that cyclo(Phe-Pro) inhibits the growth of HT-29, MCF-7 and HeLa cells and induces apoptosis in HT-29 colon cancer cells, suggesting a potential antitumour activity.

Annexin A5↗