Physiological role of short peptides in nutrition

Preparation of Type II Collagen Short Peptides: Temperature Conditions of Cartilage Homogenization and Collagen Hydrolysis

Physicochemical properties of hyaline cartilage homogenates were studied by the method of microcalorimetry. Collagen hydrolysates were obtained after homogenization of hyaline cartilages under high pressure conditions at the temperatures that denaturate collagen. Thermodynamic parameters of thermal transition of collagen in cartilage suspension were determined. Enthalpy of thermal transition ΔН decreases in comparison with the control. Thermal transition half-width ΔТ varies with temperature. More denatured and homogeneous samples were obtained at homogenization temperature 80°C. According to spectral studies, particles in the samples obtained at the temperature of 80°C were smaller. The temperature of 80°C is preferred for homogenizing hyaline cartilages and obtaining collagen type II short peptides.

Thermostable Recombinant Polypeptides as the Source of L-Amino Acids for Culture Media

Mutant homologues of small chemotactic and DNA-binding proteins from thermophilic bacteria Thermotoga petrophila RKU-1 and Thermotoga naphthophila were obtained. These proteins can be expressed in the recombinant form in E. coli cells. A wide range of properties and parameters that are important for isolation of these proteins were revealed: stability in a wide temperature and pH range, high level of expression, solubility, and the possibility of using simple purification schemes with low number of successive steps. The positive effect of proteins on in vitro fibroblasts growth was demonstrated. The described properties of the target proteins indicate the possibility of their use in different biotechnology industries as an inexpensive source of L-amino acids.

Hypolipidemic and hypoglycemic effect of peptide Lys-Glu-Trp-NH(2) in rats with associated metabolic disorders

The effect of peptide Lys-Glu-Trp-NH2 in doses of 0.2, 20, and 2000 μg/kg on lipid and carbohydrate metabolism was studied in Wistar rats with experimental hyperlipidemia and diabetes mellitus. This tripeptide in a dose of 2000 μg/kg produced a hypolipidemic effect on atherogenic lipoproteins, decreased the intensity of LPO, improved the state of the antioxidant system, and normalized the content of HDL. Treatment with this tripeptide had a hypolipidemic effect and reduced the severity of specifi c morphofunctional changes in the pancreatic and hepatic tissue.

Characterization of N-Boc/Fmoc/Z-N'-formyl-gem-diaminoalkyl derivatives using electrospray ionization multi-stage mass spectrometry

N-Boc/Fmoc/Z-N'-formyl-gem-diaminoalkyl derivatives, intermediates particularly useful in the synthesis of partially modified retro-inverso peptides, have been characterized by both positive and negative ion electrospray ionization (ESI) ion-trap multi-stage mass spectrometry (MS(n)). The MS(2) collision induced dissociation (CID) spectra of the sodium adduct of the formamides derived from the corresponding N-Fmoc/Z-amino acids, dipeptide and tripeptide acids show the [M + Na-NH2CHO](+) ion, arising from the loss of formamide, as the base peak. Differently, the MS(2) CID spectra of [M + Na](+) ion of all the N-Boc derivatives yield the abundant [M + Na-C4H8](+) and [M + Na-Boc + H](+) ions because of the loss of isobutylene and CO2 from the Boc protecting function. Useful information on the type of amino acids and their sequence in the N-protected dipeptidyl and tripeptidyl-N'-formamides is provided by MS(2) and subsequent MS(n) experiments on the respective precursor ions. The negative ion ESI mass spectra of these oligomers show, in addition to [M-H](-), [M + HCOO](-) and [M + Cl](-) ions, the presence of in-source CID fragment ions deriving from the involvement of the N-protecting group. Furthermore, MS(n) spectra of [M + Cl](-) ion of N-protected dipeptide and tripeptide derivatives show characteristic fragmentations that are useful for determining the nature of the C-terminal gem-diamino residue. The present paper represents an initial attempt to study the ESI-MS behavior of these important intermediates and lays the groundwork for structural-based studies on more complex partially modified retro-inverso peptides.

Papain-specific activating esters in aqueous dipeptide synthesis

Enzymatic peptide synthesis has the potential to be a viable alternative for chemical peptide synthesis. Because of the increasing commercial interest in peptides, new and improved enzymatic synthesis methods are desirable. In recently developed enzymatic strategies such as substrate mimetic approaches and enzyme-specific activation, use of the guanidinophenyl ester (OGp) group has been shown to suffer from some drawbacks. OGp esters are sensitive to spontaneous chemical hydrolysis and the group is expensive to synthesize and therefore not suitable for large-scale applications. On the basis of earlier computational studies, we hypothesized that OGp might be replaceable by simpler ester groups to make the enzyme-specific activation approach to peptide bond formation more accessible. To this end, a set of potential activating esters (Z-Gly-Act) was designed, synthesized, and evaluated. Both the benzyl (OBn) and the dimethylaminophenyl (ODmap) esters gave promising results. For these esters, the scope of a model dipeptide synthesis reaction under aqueous conditions was investigated by varying the amino acid donor. The results were compared with those obtained from a previous study of Z-X(AA) -OGp esters. Computational docking analysis of the set of esters was performed in order to provide insight into the differences in the reactivities of all the potential activating esters. Finally, selected ODmap- and OBn-activated amino acids were applied in the synthesis of two biologically active dipeptides on preparative scales.

Effect of tetrapeptide on insulin biosynthesis in rats with alloxan-induced diabetes

Analysis of amino acid sequences of insulinotropic polypeptides revealed a common short fragment consisting of four amino acid residues. We synthesized KEDWa tetrapeptide, analog of this fragment protected from the effects of gastrointestinal proteinases. This tetrapeptide partially restored insulin synthesis in rats with alloxan-induced diabetes. The slope of the sugar curve in this case was similar to that in normal animals. Presumably, this tetrapeptide activates the preproinsulin gene promotor site via complementary interactions with the ggcagg and cctgcc nucleotide sequences of the leading strand of double-stranded DNA.