prolylglycine and glycylproline

Our own data and data from the literature on the regulatory role of the simplest proline-containing peptides GP, PG, PGP, GPGG, and cyclic-PG are summarized. These peptides are involved in homeostasis of gastric mucosa and the anticoagulant and fibrinolytic potential of blood plasma. They also potentiate memory consolidation processes in the central nervous system. The most probable sources of these peptides are polypeptide precursors of collagen, elastin, and enterostatin.

Topics: Animals; Blood Coagulation; Dipeptides; Fibrinolysis; Gastric Mucosa; Homeostasis; Humans; Memory; Oligopeptides; Proline

Folding motifs of the secondary structures of peptides and proteins are primarily based on the hydrogen bonding interactions in the backbone as well as the sequence of the amino acid residues present. For instance, the β-turn structure directed by the Pro-Gly sequence is the key to the β-hairpin structure of peptides/proteins as well as a selective site for the enzymatic hydroxylation of pro-collagen. Herein, we have investigated the sequence dependent folding motifs of end-protected Gly-Pro and Pro-Gly dipeptides using a combination of gas phase laser spectroscopy, quantum chemistry calculations, solution phase IR and NMR spectroscopy and single crystal X-Ray diffraction (XRD). All three observed conformers of the Gly-Pro peptide in the gas phase have been found to have extended β-strand or polyproline-II (PP-II) structures with C5-C7 hydrogen bonding interactions, which correlates well with the structure obtained from solution phase spectroscopy and XRD. On the other hand, we have found that the Pro-Gly peptide has a C10/β-turn structure in the solution phase in contrast to the C7-C7 (

Topics: Dipeptides; Hydrogen Bonding; Magnetic Resonance Spectroscopy; Oligopeptides; Peptides; Protein Conformation

The role of PEPT1 in the uptake of intact peptides as compared to hydrolysis prior to uptake of their constituents is unknown. Here, dipeptides, tripeptides, and amino acids are quantified to study the fate of selected peptides in different intestinal models.. An LC-MS/MS-based method is applied for the simultaneous assessment of rates of hydrolysis and transport of a peptide panel in Caco-2 transwell cell culture, in vitro and in vivo in mice expressing or lacking PEPT1, and in hydrolysis studies in vitro using human intestinal samples. It is shown that susceptibility to hydrolysis of peptides at the brush border membrane or within epithelial cells is practically identical in all tested models and strictly structure-dependent. Peptides with high luminal disappearance show substantial hydrolysis and low basolateral appearance, while peptides with low disappearance show strong PEPT1 dependency and high basolateral appearance in intact form in Caco-2 transwell culture.. Hydrolysis and transport of intact peptides are highly variable and structure-dependent. For peptides possessing less polar N-terminal residues, hydrolysis usually dominates over transport via PEPT1. For other peptides with high intrinsic hydrolysis resistance, including anserine, carnosine, ɣ-glutamyl-dipeptides, and aminocephalosporins, PEPT1 is the main determinant for appearance in peripheral blood.

Topics: Amino Acids; Animals; Caco-2 Cells; Chromatography, Liquid; Dipeptides; Female; Humans; Hydrolysis; Intestinal Absorption; Intestinal Mucosa; Male; Mice, Inbred C57BL; Mice, Knockout; Peptide Transporter 1; Peptides; Protein Transport; Proteolysis; Tandem Mass Spectrometry

To study the chemical constituents of n-butanol extract in the broth of Myrothecium verrucaria.. The chemical constituents were isolated,purified and identified by various chromatographic and spectral techniques.. 14 compounds were isolated and identified from n-butanol extracts of Myrothecium verrucaria broth. They were identified as cyclo-( Pro-Phe)( 1),cyclo-( 4-OH-Pro-Phe)( 2),cyclo-( 4-OH-Pro-Leu)( 3),cyclo-( Ala-Pro)( 4),cyclo-( 4-methyl-Pro-9-propyl-Gly)( 5),cyclo-( Pro-Gly)( 6),cyclo-( Phe-Gly)( 7),cyclo-( Leu-Leu)( 8),N-acetyl tryptamine( 9),N-( 2-phenylethyl) acetamide( 10),N-( 2-hydroxyphenethyl) acetamide( 11),N-( 4-hydroxyphenethyl) acetamide( 12),uracil( 13) and thymine( 14).. Compounds 1 ~ 14 are obtained from the strain Myrothecium verrucaria for the first time.

Topics: 1-Butanol; Dipeptides

l-Amino acid ligase (Lal) catalyzes dipeptide synthesis from unprotected l-amino acids by hydrolysis ATP to ADP. Each Lal displays unique substrate specificity, and many different dipeptides can be synthesized by selecting suitable Lal. We have already successfully synthesized Met-Gly selectively by replacing the Pro85 residues of Lal from Bacillus licheniformis (BL00235). From these results, we deduced that the amino acid residue at position 85 had a key role in enzyme activity, and applied these findings to other Lals. When Pro and Gly were used as substrates, TabS from Pseudomonas syringae, synthesized the salt taste enhancing dipeptide Pro-Gly and other three dipeptides (Gly-Pro, Pro-Pro, and Gly-Gly) was hardly synthesized from its substrate specificity. However, the amount of Pro-Gly was low. Therefore, to alter the substrate specificity and increase the amount of Pro-Gly, we selected amino acid residues that might affect the enzyme activity, Ser85 corresponding to Pro85 of BL00235, and His294 on the results from previous studies and the predicted structure of TabS. These residues were replaced with 20 proteogenic amino acids, and Pro-Gly synthesizing reactions were conducted. The S85T and the H294D mutants synthesized more Pro-Gly than wild-type. Furthermore, the S85T/H294D double mutant synthesized considerably more Pro-Gly than the single mutant did. These results showed that the amino acid position 85 of TabS affect the enzyme activity similarly to BL00235. In addition, replacing the amino acid residue positioning around the N-terminal substrate and constructing the double mutant led to increase the amount of Pro-Gly.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Amino Acids; Dipeptides; Glycine; Hydrolysis; Kinetics; Ligases; Mutagenesis, Site-Directed; Proline; Pseudomonas syringae; Substrate Specificity

Topics: Administration, Intranasal; Administration, Intravenous; Animals; Area Under Curve; Blood; Blood Chemical Analysis; Brain; Central Nervous System Agents; Dipeptides; Male; Oligopeptides; Proline; Proteolysis; Rats, Wistar; Time Factors

Intranasal administration of Semax, peptide Pro-Gly-Pro, and a mixture of peptides Pro-Gly+Gly-Pro to rats for 5 days enhanced anticoagulant and fibrinolytic potential of the plasma (total fibrinolytic activity and plasmin and plasminogen activator activities) and decreased antiplasmin concentration. Semax and Pro-Gly-Pro decreased the weight of thrombi during experimental thrombosis.

Topics: Adrenocorticotropic Hormone; Animals; Anticoagulants; Blood Coagulation; Dipeptides; Fibrinolysin; Fibrinolysis; Fibrinolytic Agents; Humans; Male; Oligopeptides; Peptide Fragments; Proline; Rats

Intraperitoneal administration of the PGP did not change basal mucosal blood flow, whereas the PG and GP significantly decreased it. Ethanol and Indomethacin caused a rapid and stable decrease in the blood flow. Administration of the PGP prior to ethanol abolished this effect. Injections of the PGP and PG following Indomethacin administration prevented reduction of the mucosal blood flow. Administration of the GP did not change the blood flow decrease induced with Indomethacin. The mucosal blood flow correction seems to be one of the possible mechanisms of the PGP and PG antiulcer effect. The effect seems to be realised through a change in the CNS activity.

Topics: Animals; Anti-Ulcer Agents; Dipeptides; Ethanol; Gastric Mucosa; Indomethacin; Male; Oligopeptides; Proline; Rats; Regional Blood Flow

Topics: Acetylcholine; Animals; Dipeptides; Drug Interactions; Glycine; Heart; In Vitro Techniques; Male; Muscle, Smooth; Myocardial Contraction; Norepinephrine; Proline; Ranidae; Rats; Seminiferous Tubules

Renal metabolism of Glycyl-glycine (Gly-gly), Glycyl-proline (Gly-pro) and Prolyl-glycine (Pro-gly) was studied in the non-filtering, isolated perfused rat kidney. Gly-gly is metabolized by more than 90% after 120 min of perfusion. Gly-pro is more resistant to degradation and about 75% of the original peptide can be found intact in the perfusate at the end of perfusion. For Pro-gly, only 25% remains intact at the end of the experiment. Glycine was also monitored as another marker for dipeptide degradation and its production increased throughout the perfusion time. In some experiments we also determined the production of proline. We conclude from these experiments that the basolateral membrane, or perhaps the kidney blood vessels, possess an efficient apparatus for the hydrolysis of Gly-gly and Pro-gly. This mechanism is less efficient in the case of Gly-pro. This confirms an earlier hypothesis that dipeptide metabolism does not occur solely in the brush-border membranes.

Topics: Animals; Dipeptides; Glycylglycine; Kidney; Male; Perfusion; Rats; Rats, Inbred Strains