热稳定甜味蛋白马槟榔II的二硫键桥结构。
Disulfide bridge structure of the heat-stable sweet protein mabinlin II.
作者信息
Nirasawa S, Liu X, Nishino T, Kurihara Y
机构信息
Department of Chemistry, Faculty of Education, Yokohama National University, Japan.
出版信息
Biochim Biophys Acta. 1993 Oct 6;1202(2):277-80. doi: 10.1016/0167-4838(93)90016-k.
The heat-stable sweet protein mabinlin was composed of a A-chain of 33 amino-acid residues and a B-chain of 72 amino-acid residues (Liu, X., Maeda, S., Hu, Z., Aiuchi, T., Nakaya, K. and Kurihara, Y. (1993) Eur. J. Biochem. 211, 281-287). A-chain and B-chain contain two and six cysteine residues, respectively. The formation of two interchain disulfide bridges at Cys(A5)-Cys(B21) and Cys(A18)-Cys(B10), and two intrachain disulfide bridges at Cys(B11)-Cys(B59) and Cys(B23)-Cys(B67) were determined by amino-acid sequencing and composition analysis of cystine-containing peptides isolated by HPLC. Cleavage of the disulfide bridges with dithiothreitol results in complete loss of the sweet activity of mabinlin II. It was suggested that the structure fixed by four disulfide bridges contributes to heat stability of mabinlin II.
热稳定甜味蛋白马槟榔甜蛋白由一条含33个氨基酸残基的A链和一条含72个氨基酸残基的B链组成（Liu, X., Maeda, S., Hu, Z., Aiuchi, T., Nakaya, K. 和Kurihara, Y. (1993) Eur. J. Biochem. 211, 281 - 287）。A链和B链分别含有两个和六个半胱氨酸残基。通过对经高效液相色谱法分离得到的含胱氨酸肽段进行氨基酸测序和组成分析，确定了在Cys(A5)-Cys(B21)和Cys(A18)-Cys(B10)处形成了两个链间二硫键，以及在Cys(B11)-Cys(B59)和Cys(B23)-Cys(B67)处形成了两个链内二硫键。用二硫苏糖醇裂解二硫键会导致马槟榔甜蛋白II的甜味活性完全丧失。有人提出，由四个二硫键固定的结构有助于马槟榔甜蛋白II的热稳定性。
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