1P50

Transition state structure of an Arginine Kinase mutant

1P50 の概要

• エントリーDOI: 10.2210/pdb1p50/pdb
• 分子名称: Arginine kinase, MAGNESIUM ION, ADENOSINE-5'-DIPHOSPHATE, ... (6 entities in total)
• 機能のキーワード: phosphagen kinase, transition state, transferase
• 由来する生物種: Limulus polyphemus (Atlantic horseshoe crab)
• 細胞内の位置: Cytoplasm: P51541
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 40806.30

構造登録者

Pruett, P.S.,Azzi, A.,Clark, S.A.,Yousef, M.S.,Gattis, J.L.,Somasundarum, T.,Ellington, W.R.,Chapman, M.S. (登録日: 2003-04-24, 公開日: 2003-06-17, 最終更新日: 2023-08-16)

主引用文献

Pruett, P.S.,Azzi, A.,Clark, S.A.,Yousef, M.S.,Gattis, J.L.,Somasundaram, T.,Ellington, W.R.,Chapman, M.S.
The putative catalytic bases have, at most, an accessory role in the mechanism of arginine kinase.
J.Biol.Chem., 278:26952-26957, 2003

PubMed Abstract: Arginine kinase is a member of the phosphagen kinase family that includes creatine kinase and likely shares a common reaction mechanism in catalyzing the buffering of cellular ATP energy levels. Abstraction of a proton from the substrate guanidinium by a catalytic base has long been thought to be an early mechanistic step. The structure of arginine kinase as a transition state analog complex (Zhou, G., Somasundaram, T., Blanc, E., Parthasarathy, G., Ellington, W. R., and Chapman, M. S. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 8449-8454) showed that Glu-225 and Glu-314 were the only potential catalytic residues contacting the phosphorylated nitrogen. In the present study, these residues were changed to Asp, Gln, and Val or Ala in several single and multisite mutant enzymes. These mutations had little impact on the substrate binding constants. The effect upon activity varied with reductions in kcat between 3000-fold and less than 2-fold. The retention of significant activity in some mutants contrasts with published studies of homologues and suggests that acid-base catalysis by these residues may enhance the rate but is not absolutely essential. Crystal structures of mutant enzymes E314D at 1.9 A and E225Q at 2.8 A resolution showed that the precise alignment of substrates is subtly distorted. Thus, pre-ordering of substrates might be just as important as acid-base chemistry, electrostatics, or other potential effects in the modest impact of these residues upon catalysis.

PubMed: 12732621
DOI: 10.1074/jbc.M212931200

実験手法

X-RAY DIFFRACTION (2.8 Å)