Preparation of photoreactive derivatives of α‐melanotropin by selective modification of the lysine or tryptophan residue

Abstract

Photoreactive derivatives of α‐melanotropin were prepared by selective modification of the single tryptophan residue in position 9 or the amino group of the lysine residue in position 11 by reaction with 2‐nitro‐4‐azidophenylsulfenyl chloride. [2‐Nitro‐4‐azidophenylsulfenyl‐Trp9]‐α‐melanotropin was found to be five times as potent as α‐melanotropin in stimulating lipolysis in isolated rabbit adipocytes. [Nε‐2‐nitro‐4‐azidophenylsulfenyl‐Lys11]‐α‐melanotropin had only 11% of the lipolytic potency of α‐melanotropin.