1A39

HUMICOLA INSOLENS ENDOCELLULASE EGI S37W, P39W DOUBLE-MUTANT

1A39 の概要

• エントリーDOI: 10.2210/pdb1a39/pdb
• 分子名称: ENDOGLUCANASE I, 2-acetamido-2-deoxy-beta-D-glucopyranose (3 entities in total)
• 機能のキーワード: endoglucanase, hydrolase, cellulase, cellulose degradation, glycoside hydrolase family 7, glycosylated protein
• 由来する生物種: Humicola insolens
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 45019.58

構造登録者

Davies, G.J.,Ducros, V.,Lewis, R.J.,Borchert, T.V.,Schulein, M. (登録日: 1998-01-28, 公開日: 1999-03-02, 最終更新日: 2024-10-30)

主引用文献

Davies, G.J.,Ducros, V.,Lewis, R.J.,Borchert, T.V.,Schulein, M.
Oligosaccharide specificity of a family 7 endoglucanase: insertion of potential sugar-binding subsites.
J.Biotechnol., 57:91-100, 1997

PubMed Abstract: Family 7 of the glycosyl hydrolases contains both endoglucanases and cellobiohydrolases. In addition to their different catalytic activities on crystalline substrates, the cellobiohydrolases differ from the endoglucanases in their activity on longer soluble substrates, indicative of a greater number of subsites on the enzyme. A double mutant (S37W, P39W) of the Humicola insolens endoglucanase I (EG I) has been constructed in order to mimic aspects of the subsite structure of the corresponding family 7 cellobiohydrolase, cellobiohydrolase-I (CBH I). The 3-D crystal structure of the double mutant has been solved and refined to a crystallographic R-factor of 0.17 at a resolution of 2.2 A (1 A = 0.1 nm). The two mutant tryptophans are clearly visible in the electron density and are in the same orientation as those found in the substrate binding groove of CBH I. In addition to the substitutions, the C-terminal amino acids (399QELQ), disordered in the native enzyme structure, are clearly visible and there are a small number of minor loop movements associated with differences in crystal packing. Kinetic determinations show that the S37W, P39W mutant EG I has almost identical activity, compared to native EG I, on small soluble cellodextrins. On phosphoric acid swollen cellulose there is a small (30%), but significant, decrease in the apparent KM indicating that the double mutant may indeed exhibit stronger binding to longer polymeric substrates.

PubMed: 9335168
DOI: 10.1016/S0168-1656(97)00092-8

実験手法

X-RAY DIFFRACTION (2.2 Å)