Chemoenzymatic Synthesis of Peptidyl 3,4-Dihydroxyphenylalanine for Structure–Activity Relationships in Marine Invertebrate Polypeptides

✍ Scribed by Steven W. Taylor

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 77 KB
• Volume: 302
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1006/abio.2001.5522

✦ Synopsis

An improved method for hydroxylating tyrosine-containing sequences in polypeptides to peptidyl 3,4-dihydroxyphenylalanine (DOPA) using mushroom tyrosinase at relatively high enzyme-to-substrate ratios is described. The new method involves incorporating borate into the reaction mixture to stop formation of the unwanted side product 3,4,5-trihydroxyphenylalanine. Using this method, a model for the palindromic central sequence for the antimicrobial peptide family, the styelins, Y*Y*KHKY*Y* (where Y* is DOPA), was successfully synthesized in high yield from YYKHKYY. This sequence represents a particularly challenging target because of the cluster of four precursor tyrosine residues are in close proximity. The method should be readily applied to larger polypeptides produced by either solid-phase synthesis or recombinant techniques and give greater insight into the roles of this unusual posttranslational modification in marine invertebrates such as mussels and ascidians.