A Biotechnological Procedure for Preparing Short Peptides and Their Radioactively Labeled Analogs for Estimating Specific Binding of Semax and Its Metabolites in Various Sections of Rat Brain

摘要

The peptides His-Phe-Pro-Gly-Pro and Phe-Pro-Gly-Pro, as well as their tritium-labeled analogs, were prepared by biotechnological methods from peptides of the melanocortin series using amino-acylaryl-amidase (E.C. 3.4.11.2) (yield >60percent) and glutamate-specific aminopeptidase Bacillus intermedius Glutamyl Endopeptidase (E.C. 3.4.21.19) (yield 100percent). With the latter enzyme, it is possible to prepare the peptides and their modified analogs from precursors containing a Glu residue in the amino acid sequence. The biotechnological method allows synthesis of peptides in preparative amounts in a high yield, without formation of by-products. With radioactively labeled compounds as substrate, the biosynthesis yields peptides identical in the radiochemical characteristics. Experiments with labeled peptides revealed the existence of centers of specific binding in different sections of rat brain for different Semax metabolites.