[an error occurred while processing this directive]

Plant Diversity ›› 1996, Vol. 18 ›› Issue (02): 1-3.

• 研究论文 •    

耐热甜味蛋白Brazzein的特性和化学修饰

丁鸣;Goran Hellekant;胡忠   

  1. 中国科学院昆明植物研究所,昆明 650204
  • 出版日期:1996-04-25 发布日期:1996-04-25

CHARACTERIZATION AND CHEMICAL MODIFICATION OF BRAZZEIN, A HIGH POTENCY THERMOSTABLE SWEET PROTEIN FROM PENTADIPLANDRA BRAZZEANA

DING Ming, Goran Hellekant, HU Zhong   

  1. AHABS, University of Wisconsin-Madison, 1655 Linden Dr., Madison, WI 53706, USA;Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China
  • Online:1996-04-25 Published:1996-04-25

摘要: Ming and Hellekant(1994)从西非洲热带野生植物 Pentadiplandra brazzeana Baill.的果实中,分离出一种甜味蛋白质,命名为brazzein,它是由54个氨基酸残基组成的单链多肽;甜度是蔗糖的2000倍。本实验测得 Brazzein分子量为 6.5 kD,等电点为 5。Brazzein含有 8个半胱氨酸,构成分子内的双硫键;其水溶液经 80℃,4 h处理,甜味和电泳行为不变。虽然 Brazzein的氨基酸序列与芥菜蛋白酶抑制剂MTI—2有高的同源性,但未测出有蛋白酶抑制剂活性。根据氨基酸序列的计算机分析表明:Brazzein是亲水性多肽;二级结构主要是β-折途和β-转角。蛋白质印迹分析显示,Brazzein抗血清与甜味蛋白curculin,mabinlin和miraculin有强的交叉反应。Brazzein的S-基化修饰引起甜味的丧失,同时也丧失与抗血清的免疫反应。Brazzein中赖氨酸ε-氨基的酰化,酪氨酸酚羟基的碘化,组氨酸咪唑基和精氨酸胍基的修饰均导致甜味的丧失或降低;但赖氨酸ε-氨基的甲基化只改变其电泳行为,却不降低甜味。这表明Brazzein分子的表面电荷对于其甜味性质是重要的。

关键词: pentadiplandra brazzeana, 甜味蛋白质, 化学修饰

Abstract: A sweet protein, brazzein, has been discovered from the fruits of Pentadiplandra brazzeana B., a tropical wild plant in west Africa. Brazzein has 54 amino acid residues; it is 2000 times sweeter than sucrose (Ming and Hellekant, 1994 ). In this article, further characterization shows that its molecular weight is 6.5 kD and isoelectric point is 5. It has 8 cysteines and they form four disulfide bonds. After treating its aqueous solution at 80 ℃ for 4 hrs, no changes in sweetness and behavior of electrophoresis are found. Secondary structures predictions suggests that beta turns and beta sheets are the dominant structures in the protein.

Key words: Pentadiplandra brazzeana, Sweet protein brazzein, Chemicl modification