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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 I-对其的淬灭能力
Fluorescence spectroscopy was used to study the endogenous fluorescence properties, I-kinetic fluorescence quenching, and bis-ANS-conjugated fluorescence of human gastric gastrin (GIP-42) and its analogues obtained by solid-phase synthesis. The results showed that GIP-4 2 had a certain conformation in solution, and the fluorescence of Trp residue was biphasic by I-quenching with the quenching constants of 11.5 L / mol and 1.2 L / mol, respectively. GIP-4 2 peptide has a hydrophobic region can be combined with the probe bis-ANS; Trp residues more exposed to aqueous solution in the 25 peptide (GIP-25) molecules obtained after removing the 17 residues at the N-terminal , More easily I-quenched. At the same time, the hydrophobicity of the bis-ANS binding region in its molecule is weak, suggesting that the N-terminal 17 peptide is very important for maintaining the viable conformation of human GIP-42. In addition, the His residue in human GIP-42 was modified to not alter the polarity of the microenvironment of tryptophan residues in the peptide, but to reduce its I-quenching capacity