应用荧光光谱法研究植物LEA3蛋白11-氨基酸基序的保护功能

摘要

胚胎晚期富集蛋白(late embryogenesis abundant,LEA)是增强生物抵抗干旱、低温和盐渍等多种胁迫的重要功能蛋白,但其保护机理仍不清楚.本文利用紫外光谱法证实,含多拷贝11-氨基酸基序的多肽(如PM2D和PM2E)可较好的保护经冻融的乳酸脱氢酶(LDH)活性.进一步通过荧光光谱法证实,含多拷贝11-氨基酸基序的多肽可通过多位点协同结合模式,稳定LDH酶的结构.而含低拷贝11-氨基酸基序的多肽(如PM2F和PM2G)与LDH酶只有一种结合位点,二者的结合强度较弱,因而不能表现出对LDH酶活性的保护作用.此外,含多拷贝11-氨基酸的多肽与海藻糖在保护LDH酶活性上存在协同作用,且二者有着不同的保护机理.%Late embryogenesis abundant protein (LEA) can enhance the tolerance of organisms under drought, low-temperature and other stress conditions. However, their protection mechanisms are still unclear. In the present paper, the peptides consisting of multi-copies of 11-amino acid motif, such as PM2D and PM2E are proved to protect the activity of the lactate dehydrogenase (LDH) from freeze-thaw by using ultroviolet spectrometry. Furthermore, the fluorescence spectroscopic results show that the peptide consisting of multi-copies of 11-amino acid can stabilize the structure of LDH through synergy and multi-sites binding. However, the peptides consisting of less copies of 11-amino acid, such as PM2F and PM2G bind to LDH through one site,and the binding is weak. They thus can not protect the activity of LDH. In addition, the peptides consisted of multi-copies of 11-amino acid protect LDH by acting with trehalose synergically, and the protection mechanisms of LEA and trehalose on LDH are different.