1TDY

DISSECTION OF THE FUNCTIONAL ROLE OF STRUCTURAL ELEMENTS OF TYROSINE-63 IN THE CATALYTIC ACTION OF HUMAN LYSOZYME

1TDY の概要

• エントリーDOI: 10.2210/pdb1tdy/pdb
• 分子名称: HUMAN LYSOZYME (2 entities in total)
• 機能のキーワード: hydrolase (o-glycosyl)
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Secreted: P61626
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 14743.73

構造登録者

Harata, K.,Muraki, M.,Jigami, Y. (登録日: 1992-08-06, 公開日: 1993-01-15, 最終更新日: 2024-11-20)

主引用文献

Muraki, M.,Harata, K.,Jigami, Y.
Dissection of the functional role of structural elements of tyrosine-63 in the catalytic action of human lysozyme.
Biochemistry, 31:9212-9219, 1992

PubMed Abstract: The functional role of tyrosine-63 in the catalytic action of human lysozyme (EC 3.2.1.17) has been probed by site-directed mutagenesis. In order to identify the role of Tyr63 in the interaction with substrate, both the three-dimensional structures and the enzymatic functions of the mutants, in which Tyr63 was converted to phenylalanine, tryptophan, leucine, or alanine, have been characterized in comparison with those of the wild-type enzyme. X-ray crystallographical analysis of the mutant enzyme at not less than 1.77-A resolution indicated no remarkable change in tertiary structure except the side chain of 63rd residue. The conversion of Tyr63 to Phe or Trp did not change the enzymatic properties against the noncharged substrate (or substrate analogs) largely, while the conversion to Leu or Ala markedly reduced the catalytic activity to a few percent of wild-type enzyme. Kinetic analysis using p-nitrophenyl penta-N-acetyl-beta-(1----4)-chitopentaoside (PNP-(GlcNAc)5) as a substrate revealed that the reduction of activity should mainly be attributed to the reduction of affinity between enzyme and substrate. The apparent contribution of the phenolic hydroxyl group and the phenol group in the side chain of Tyr63 was estimated to 0.4 +/- 0.4 and 2.5 +/- 0.8 kcal mol-1, respectively. The result suggested that the direct contact between the planar side-chain group of Tyr63 and the sugar residue at subsite B is a major determinant of binding specificity toward a electrostatically neutral substrate in the catalytic action of human lysozyme.

PubMed: 1390708
DOI: 10.1021/bi00153a014

実験手法

X-RAY DIFFRACTION (1.7 Å)