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Racemization in the synthesis of polytripeptide models of collagen
Author(s) -
Rapaka Rao S.,
Bhatnagar R. S.,
Nitecki D. E.
Publication year - 1976
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1976.360150209
Subject(s) - racemization , tripeptide , chemistry , amino acid , monomer , peptide synthesis , hydrogenolysis , saponification , organic chemistry , peptide , dipeptide , levulinic acid , stereochemistry , polymer , biochemistry , catalysis
Racemization in the synthesis of tripeptide intermediates and their polymers was investigated, using L ‐amino acid oxidase. Stepwise investigation of peptide intermediates showed no racemization during peptide coupling steps or deprotection of benzyl esters by hydrogenolysis. Saponification of one of the methyl esters produced some racemization. Preparation of active esters from N ‐protected tripeptide acids containing optically active C‐terminal amino acid, with one exception, produced racemization. The fractionated polymers were found to contain less racemized amino acids than the crude products or starting monomeric tripeptides, indicating that the racemized sequences gave rise to lower molecular‐weight oligomers. The sequences investigated were ‐Pro‐Pro‐Ala‐, ‐Ala‐Pro‐Pro‐, ‐Val‐Pro‐Pro‐, ‐Pro‐Pro‐Leu‐, ‐Pro‐Gly‐Leu‐, ‐Pro‐Gly‐Phe‐, ‐Pro‐Gly‐Val‐, ‐Gly‐Val‐Pro‐, ‐Phe‐Pro‐Gly‐, ‐Leu‐Pro‐Gly‐, and Ile‐Pro‐Gly‐.