Biochemical significance of the non-common amino acid sequences specifying the common functions of enzymes, polysaccharide lyases

指定酶、多糖裂解酶的常见功能的非常见氨基酸序列的生化意义

基本信息

批准号：
14360052
负责人：
MURATA Kousaku
金额：
$ 8.51万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Polysaccharide lyase is an enzyme catalyzing the depolymerization of polysaccharides such as alginate, xanthan, gellan, and hyarunonate, all of which are produced by bacteria, and gives rise oligosaccharides or monosaccharides as reaction products. The enzyme strictly recognizes uronic acids scattered on the polysaccharide molecules and splits the polysaccharides at the acid site through β-elimination reaction. However, these enzymes have no similarities in their primary structures, thus suggesting that the function of these enzymes are written by different amino acid sequences. To elucidate the reason why the enzymes with the different primary structures could show the same substrate recognition and β-elimination reaction, the X-ray crystal structures of Sphingomonas sp. A1 alginate lyase (A1-III), Pseudomonas aeruginosa PAO1 alginate lyase (PA1167), and Bacillus sp.GL1 xanthan lyase were determined and compared with those of porcine kidney N-acyl-D-glucoamine 2-epimerase and Bacillus … More sp.GL1 unsaturated glucuronylhydrolase. The structural comparison of these enzymes indicated that (1)A1-III expresses β-eliination activity by using a lid-loop module. Such the structure is also found in XL, although PA1167 has not. (2) A1-III has α/α -barell structure. PA1167 shows anti-parallel β-sheet structure. XL shows a combined structure of α/α -barrell structure and anti-paralell β-sheet structure. (3)In all the polysaccharide lyases examined, Tyr is an essential catalytic amino acid residue, and His and Arg are involved in the recognition and stabilization of substrate. From these results, it was concluded that, even though the primary structure is different, similar structure for catalytic site and substrate recognition are created through the movement of protein modules. This notion indicates that the estimation of protein function on the basis of primary structure is not always reliable and definitive function of proteins should be determined in combination with the three-dimensional structures of them. Less

多糖裂解酶是一种酶，催化多糖，例如算法，黄褐色，gellan和Yararunonate的沉积，所有这些酶都是由细菌产生的，并产生产生的寡糖或单糖作为反应产物。这些酶严格识别散落在多糖分子上的尿酸，并通过β-脱颗合反应将多糖分裂在酸位点。但是，这些酶在其主要结构上没有相似性，因此表明这些酶的功能是由不同的氨基酸序列编写的。为了阐明具有不同原代结构的酶可以显示相同的底物识别和β-脱离反应的原因，即鞘氨拟补人sp的X射线晶体结构。确定并比较了A1算法（A1-III），铜绿假单胞菌PAO1算法（PA1167）和芽孢杆菌sp.Gl1 xanthan裂解酶，并与猪N-肾脏N-酰基-D-乙酰-D-葡萄糖2-蛋白酶2-粘液酶和芽孢杆菌的A1算法和比较。这些酶的结构比较表明，（1）A1-III通过使用盖环模块表达β-脱位活性。这种结构也可以在XL中找到，尽管PA1167还没有。（2）A1 -III具有α/α -barell结构。 PA1167显示抗平行β-折叠结构。 XL显示了α/α-Barrell结构和抗Paralellβ-折叠结构的组合结构。（3）在检查的所有多糖裂解酶中，Tyr是必不可少的催化氨基酸居住区，他的和ARG参与了底物的识别和稳定。从这些结果可以得出结论，即使主要结构不同，催化位点和底物识别的相似结构是通过蛋白质模块的运动创造的。该概念表明，基于一级结构的蛋白质功能的估计并不总是可靠的，应与它们的三维结构结合确定蛋白质的确定功能。较少的