Abstract: Two sweet proteins named mabinlin I and mabinlin II (Ma I , Ma I) with MW. 11.6 kD and 10.4 kD respectively had been isolated. By using Edman degradation and the method of reversed phase HPLC identification of PTH-aa, it were found that the N-terminuses of both proteins are blocked because of cyclization of pyroglutamic acid. The pyrrolidone was opened by treatment with 1 mol/l HCl-methanol at 35°C for 24 h. The eight amino acid sequence of N-terminal peptide was pyroglutamic acid-Pro-Arg-Gly-Pro-Ala-Leu-Arg-in both proteins. Dynamic analysis of the enzymatic products by carboxypeptidasc showed that the amino acid sequence of C-terminal peptide is -Phe-Gln-Leu-Ala-Scr in Ma II , and -Phe Gin-Leu-Ala in Ma II . the result means that even though the Ma II lack a Ser residue at C-terminus the main difference of the two sweet proteins is not- in the amino acid sequences of both C- and N- terminal regions.

Key words: Sweet protein

摘要： 从马槟榔（Capparis masaikai）种子中曾分离出二种甜味蛋白，称为Mabinlin和II,分子量分别为11．6kD和10．4kD。用Edman降解和反相HPLC鉴定PTH－aa方法测定证明：二者的N末端均因焦谷氨酸环化而封闭。采用 lmol／l HCL-甲醇溶液35℃处理24小时的方法可使之开环。二种蛋白N端肽8个氨基酸奶基顺序均为：Pyroglutamic acid－Pro－Arg-Gly－Pro-Ala-Leu－Arg-. 用羧肽酶酶解的动态分析证明MaI 羧端的氨基酸顺序为-Phe-Gln- Leu-Ala-Ser，MaII为-Phe-Gln-Leu-Ala. 其差别仅在于MSII缺一个Ser,这一结果表明MaI和MaII的主要差异不是在端肽。

关键词: 甜味蛋白, 马槟榔, 氨基酸顺序测定