Fermentation and Protein Biotechnology Laboratory, Department of Botany, Punjabi University, Patiala 147 002, India.
Amino Acids. 2012 Aug;43(2):973-81. doi: 10.1007/s00726-011-1162-1. Epub 2011 Nov 26.
Plant seeds, a rich source of proteins, are considered important for their application as functional ingredients in a food system. A novel ribosome-inactivating protein (RIP), balsamin was purified from the seeds of Balsam apple, Momordica balsamina. Balsamin was purified by ion exchange chromatography on CM Sepharose and gel filtration on superdex-75. It has a molecular weight of 28 kDa as shown by SDS-PAGE analysis. Balsamin inhibits protein synthesis in a rabbit reticulocyte lysate-based cell free translation assay with an IC(50) of 90.6 ng ml(-1). It has RNA N-glycosidase activity and releases a 400-base long fragment termed the Endo fragment from 28S rRNA in the same manner as does saporin-6 from Saponaria officinalis. The N-terminal sequence analysis of the first 12 amino acids of balsamin revealed that it shares 83% similarity with type I RIP α-MMC from Momordica charantia and 50% similarity with β-MMC (from Momordica charantia), bryodin I (from Bryonia dioica) and luffin a (from Luffa cylindrica). Balsamin was further characterized by mass spectrometry. CD spectroscopic studies indicate that secondary structure of balsamin contains helix (23.5%), β-strand (24.6%), turn (20%) and random coil (31.9%). Thus RIPs activity expressed in vegetables like Momordica sp. advocates its usage in diet.
植物种子是蛋白质的丰富来源，被认为是作为功能性成分在食品系统中应用的重要物质。一种新型核糖体失活蛋白（RIP），巴拉斯明，从苦瓜的种子中被分离出来。巴拉斯明通过 CM Sepharose 离子交换层析和 superdex-75 凝胶过滤进行纯化。SDS-PAGE 分析表明，它的分子量为 28 kDa。巴拉斯明在兔网织红细胞裂解物无细胞翻译测定中抑制蛋白质合成，IC50 为 90.6 ng ml(-1)。它具有 RNA N-糖苷酶活性，并以与皂角苷-6 从皂角相同的方式从 28S rRNA 中释放出一个 400 碱基长的片段，称为 Endo 片段。巴拉斯明的前 12 个氨基酸的 N 末端序列分析表明，它与苦瓜的 I 型 RIP α-MMC 有 83%的相似性，与 β-MMC（来自苦瓜）、 bryodin I（来自 Bryonia dioica）和 luffin a（来自 Luffa cylindrica）有 50%的相似性。巴拉斯明进一步通过质谱进行了表征。CD 光谱研究表明，巴拉斯明的二级结构包含螺旋（23.5%）、β-链（24.6%）、转弯（20%）和无规卷曲（31.9%）。因此，像苦瓜这样的蔬菜中表达的 RIPs 活性支持其在饮食中的应用。
