Primary structure of p-momorcharin, a ribosome-inactivating protein from the seeds of Momordica Charantia Linn (Cucurbitaceae)

The complete amino acid sequence of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae) has been determined. This has been done by the sequence analysis of peptides obtained by enzymatic digestion with trypsin, chymotrypsin and S. aureus V8 protease, as well as by chemical cleavage with BNPS-skatole. The protein consists of 249 amino acid residues containing one asparagine - linked sugar group attached to the site of Asn 5 1 and has a calculated relative molecular mass of 28,452 Da without addition of the carbohydrate. Comparison of this sequence with those of trichosanthin and other ribosome-inactivating proteins from different species of plants shows a significant homology with each other. Regarding the similarity of their biological properties, an active domain of these proteins has been predicted here.     

Structure determination of glycopeptide of β-momorcharin

The structure of the N-linked oligosaccharide chain of β-momorcharin, a ribosome-inactivating protein from the seeds of Momordica charantia Linn (Cucurbitaceae), was determined. A glycopeptide liberated by pronase digestion of the glycoprotein was subjected to amino acid and neutral carbohydrate analysis to establish the composition of amino acid and sugar residues. The sequences and glycosylation hnkages of the sugar and amino acid residues in the glycopeptide were determined as Manαl-6(XyIβ1-2)-Manβ1-4GlcNAcβ1-4(Fucαl-3)-GlcNAc-Asn-Leu by 2D-NMR spectroscopy and FAB-MS data.     

天花粉蛋白一级结构的修正及不同产地天花粉蛋白的研究

胰蛋白酶酶解天花粉蛋白, 用高效液相色谱分离酶解肽段, 用顺序仪测定其有关肽段的顺序。用羧肽酶A, B, Y测定了天花粉蛋白C-端和天花粉蛋白溴化氰降解肽CB1的C-端顺序, 修正了我们1985年测定的天花粉蛋白一级结构, 证明天花粉蛋白由246(7)氨基酸残基所组成, 除C-端微观不均一外, 与Collins结果一致。同时比较了芜湖产天花粉蛋白一级结构与平湖产的天花粉蛋白一级结构, 没有发现两者的一级结构有差别。     

苦瓜子蛋白的分离纯化及真性质研究

从苦瓜种子的粗提物苦瓜子蛋白丙酮分级沉淀干粉中,用CM-Spehadex C-50和SephadexG-75分离得到了两个核糖体失活蛋白,α-苦瓜子蛋白(C-momorcharin,α-MMC和β-苦瓜子蛋白(β-momorcharin,β-MMC),其等电点分别为9.10(α-MMC),9.32(β-MMC).用ESI-MS和MALDI-TOF-MS测定它们的分子量,分别为28625(α-MMC),29076(β- MMC)(+Na,29099);,28795(α-MMC),29074.7(β-MMC).它们都是糖蛋白,其生物活性的分析测定表明,都属于RNA N-糖苷酶,本文重点对β-苦瓜子蛋白的分离纯化及其性质进行详细报道,并对其N-端部分的氨基酸顺序进行了测定.     

苦瓜子蛋白的分离纯化及其性质研究

从苦瓜种子的粗提物苦瓜子蛋白丙酮分级沉淀干粉中,用CM-SephadexC-50和SephadexG-75分离得到了两个核糖体失活蛋白,α-苦瓜子蛋白(α-momorcharin,α-MMC)和β-苦瓜子蛋白(β-momorcharin,β-MMC),其等电点分别为9.10(α-MMC),9.32(β-MMC)。用ESI-MS和MALDI-TOF-MS测定它们的分子量,分别为28625(α-MMC),29076(β-MMC)(+Na,29099);28795(α-MMC),29074.7(β-MMC)。它们都是糖蛋白。其生物活性的分析测定表明,都属于RNAN-糖苷酶。本文重点对β-苦瓜子蛋白的分离纯化及其性质进行详细报道,并对其N-端部分的氨基酸顺序进行了测定。