肽链及蛋白质N-末端羰酰荧光衍生物的形成

短肽及胰岛素的N-末端经Dixpn转氨后具有荧光发色性质,其激发与发射波长随肽链氨基酸残基的种类和数量的不同而有差异,其范围大约为Ex 312—333nm;Em 398—408nm;量子产率为0.020—0.03.荧光发色团的基本化学结构可能是N-末端α-羰酰基及其相连的酰胺基,并且N-末端第二及第三位氨基酸残基对其荧光性质有影响.在碱性溶液中(pH>9.0)它的荧光强度降低,但在NaCl溶液中随盐浓度的增加而增强.在不同浓度的CuHCl溶液中,羰酰三肽的荧光强度变化随其氨基酸残基的种类和构型的不同而有差异.以上结果提示;α-羰酰荧光衍生物可能作为蛋白及肽N-末端的荧光探剂,可能成为研究蛋白和肽结构与功能的一种手段.

FORMATION AND PROPERTIES OF OXOACYL FLUORESCENT DERIVATIVE ON N-TERMINALS OF PROTEINS AND PEPTIDES

Dixon transamination of oligopeptides and insulin results in the formation of a fluorescent derivative having emission maximum about 398-408nm with 0.02-0.03 quantum yield by the excitation at 3l2-333nm depending on the nature and length of the peptide. The chemical structure of the fluorophore may be ?-Oxo-acyl-amide which would be effected by thd second and the third amino acid residues, its intensity decreases when pH>9.0 and increases with the increment of concentrations of NaCl solution. Changes of the Oxoacyl-amide fluorescence of oligopeptides are comparatively different with their different kinds or configurations of the composed residues. It is suggested that such a fluorescence derivative may be used as a probe for the study of the conformation of the N-terminal region of peptides and proteins.