Identification of N-terminal tryptophan in peptides

✍ Scribed by J.R. Giglio

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 168 KB
• Volume: 82
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(77)90160-9

✦ Synopsis

Identification of N-terminal Tryptophan in Peptides

Because of its complete destruction during the usual hydrolysis of peptides or of dansyl (5-dimethylamino-I-naphthalenesulfonyl) peptides with 6 N HCl, tryptophan or dansyl-tryptophan (DNS-tryptophan) may not be identified after this treatment.

The destruction of tryptophan which occurs, even after a short 4-hr period of hydrolysis at 110°C (l), represents a limitation to the Edmandansyl degradation (2) for the sequencing of peptides. The identification of tryptophan along the peptide chain, thus, is usually made by exclusion (no DNS-amino acid, except for traces of DNS-serine, DNS-alanine, and DNS-glycine is detected after hydrolysis of the tryptophan-positive DNS-peptide)

or, as an alternative, by incubation of the DNS-peptide with chymotropsin or carboxypeptidase, followed by thin-layer chromatography or high-voltage electrophoresis (3). Identification by exclusion may lead to a dubious conclusion, and incubation with chymotrypsin or carboxypeptidase has had little success and is seldom used. Recently, Penke et al. ( 4) described the use of 3 N mercaptoethanesulfonic acid (MES) for the hydrolysis of peptides or proteins and reported total hydrolysis of peptide bonds within 22 hr at 110°C with very high recoveries of tryptophan (about 95%).

To investigate the possibility of using this reagent for the release of N-terminal DNS-tryptophan, synthetic peptides (Sigma Chemical Co.,