Determining the Binding Properties of Fetuin and α_1-Acid Glycoproteins Toward ＂Abrus Precatorius＂ Agglutinin by the Fluorescence Spectroscopy and Thermodynamic Analysis

利用螢光光譜及熱力學的分析來決定醣蛋白對凝集素之結合性質

邱紫文(Tzyy-Wen Chiou) ； 林宗建(Tsung-Chien Lin) ； 呂政義(Cheng-Yi Lii) ； 吳明道(Albert M. Wu)

《中央研究院化學研究所集刊》 41期 (1994/03) Pp. 103-112

https://doi.org/10.6522/BICAS.1994.41.13

摘要

本研究藉由螢光光譜法來探討相思豆之凝集素（Abrus preatorius agglutinin）的結合性質。當被螢光標記之醣蛋白與凝集素結合時，其螢光強度會下降，且此下降值為其結合量之函數。由Scatchard圖之分析得知：凝集素分子對於本實驗所探討之諸醣蛋白有四個結合位置，且其結合常數皆位於10^5M^(-1)之範圍內；然而，凝集素對fetuin之親和性較對human plasma α_1-acid glycoprotein為強。此外發現，去除唾液酸可輔助醣蛋白與凝集素之結合。由熱力學的分析得知焓（∆H），自由能（∆G）和熵（∆S）等值可提供重要資訊以決定凝集素之結合特異性。

並列摘要

The binding properties of Abrus precatorius agglutinin (APA) was studied by the method of fluorescence quenching. The fluorescence intensities of the labeled glycoproteins decreased with the increment of bound APA. From the Scatchard plot analysis, APA molecule contained four binding sites for the glycoproteins investigated. The association constants for the binding of the glycoproteins to APA were in the order of 10^5 M^(-1). And fetuin had a stronger affinity toward APA than human plasma α_1-acid glycoprotein. The desialization of the glycoprotein could facilitate the binding to APA. The ∆H, ∆G, and ∆S from thermodynamic analysis provided informative data for elucidating the binding specificity of APA.