【摘要】 从马槟榔(Capparis masaikai Levl.)种子分离鉴定了二种甜蛋白:甜蛋白Ⅰ(mabinlinⅠ或MaⅠ)分子量MW11600,等电点pI 11.8;甜蛋白Ⅱ(mabinlinⅡ或MaⅡ)MW10400,pI 11.3。另一组分mabinlinⅢ MW10200,pI 11.8,可能是提取过程产物。MaⅡ有84个氨基酸残基,比MaⅠ少15个。它们有80个氨基酸残基是共同的,都是缺丝氨酸和蛋氨酸的单一多肽链。MaⅠ还缺赖氨酸和酪氨酸。测不出有自由SH基。在8M尿素中用巯基乙醇还原处理,两种甜蛋白分子都可转变为二聚体而失去甜味。 自去壳脱脂的种子干粉中提取MaⅠ和MaⅡ的得率依所用溶剂和提取条件而异。用50％丙酮水溶液提取,继用CM-纤维素分离,甜蛋白的得率达13％。用水或0.1N pH6.2磷酸缓冲液提取,得率低于1％。更多还原

【Abstract】 Two components of sweet protein were saparated and characterized: mabinlin I (MaI), the major one, with MW of 11600 and isoelectric point pI of 11.8, and mabinlin Ⅱ (Ma Ⅱ ) with MW of 10400 and pI of 11.3. Another component mabinlin Ⅲ (Ma Ⅲ) with MW of 10200 and pI of about 11.8 was found to be produced during the extraction. MaⅡ contains 84 amino acid residues that are fewer 15 amino acid residues than Ma I , of which 6 residues are Pro. These proteins are all single polypeptide chains lacking Ser and Met. 80 amino acid residues are common in Ma I and Ma I molecules in which Arg, Glx and Pro are dominant ones. No SH group was detected. After treatment of reductive cleavage withβ -mercaptoethanol in 8 M urea, these protein molecules were transformed into dimers and lost the sweet nature.The yield and the ratio of Ma I to Ma Ⅱ extracted from the lipid-free powder of decorticated seeds depended on the solvent used and the conditions of extraction. A highest yield of 13% was obtained in extraction with 50% aqueous solution of acetone and saparation through CM-cellulose column chromato-graphy. While extraction with watar or 0.lM pH6.2 phosphate buffer the yield was less than 1% because of the less accessibility of the protein in combined state.更多还原