人抑胃肽溶液构象的荧光光谱学研究

Fluorescence Spectroscopy Study on the Conformation of Human Gastric Inhibitory Polypeptide in Solution

运用荧光光谱方法研究了用固相合成法得到的人抑胃肽 (GIP- 4 2 )及其类似物的内源荧光特性、I-动态荧光淬灭以及与 bis- ANS结合的荧光。结果表明 :GIP- 4 2在溶液中具有一定的构象 ,其 Trp残基荧光被 I-淬灭的结果表现为双相 ,淬灭常数分别为 11.5L/ mol和 1.2 L/ mol;GIP-4 2肽中有一疏水区能与探针 bis- ANS结合 ;在 N-端 17个残基除去后所得到的 2 5肽 (GIP- 2 5)分子中 ,Trp残基更多地暴露在水溶液中 ,更易被 I-淬灭。同时其分子中 bis- ANS结合区的疏水性很弱 ,提示 N-端 17肽对于维持人 GIP- 4 2具有活力必需的构象十分重要。此外 ,人 GIP- 4 2中的 His残基被修饰后并不改变肽中色氨酸残基的微环境的极性 ,但降低

The human gastric inhibitory polypeptide (GIP 42)and its analogs were studied by fluorescence spectroscopy in this paper The results indicated that in solution the GIP 42 existed in a certain conformation The quenching of the Trp fluorescence by I - was in bi phase with the quenching constants of 11 5 L/mol and 1 2L/mol respectively It was also found that there was a hydrophobic area in GIP 42 molecule which bis ANS can bind to The Trp residues in the analog GIP 25 became more exposed to solvent The Trp fluorescence of GIP 25 molecule was quenched by I - more easily and the hydrophobicity of the bis ANS binding site became much weaker, suggesting that the 17 residues in N terminus are very important in maintaining the conformation necessary for the biological activity of human GIP 42 In addition, it was found that the modification of His residues in GIP 42 did not affect the polarity of the environment of Trp residues, but it seems protect Trp from the quenching by I -