Premium
The mechanism of aconitase: 1.8 Å resolution crystal structure of the S642A:citrate complex
Author(s) -
Lloyd S. J.,
Lauble H.,
Prasad G. S.,
Stout C. D.
Publication year - 1999
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.8.12.2655
Subject(s) - aconitase , chemistry , crystallography , active site , stereochemistry , crystal structure , binding site , enzyme , biochemistry
The crystal structure of the S642A mutant of mitochondrial aconitase (mAc) with citrate bound has been determined at 1.8 Å resolution and 100 K to capture this binding mode of substrates to the native enzyme. The 2.0 A resolution, 100 K crystal structure of the S642A mutant with isocitrate binding provides a control, showing that the Ser → Ala replacement does not alter the binding of substrates in the active site. The aconitase mechanism requires that the intermediate product, cis ‐aconitate, flip over by 180° about the C α ‐C β double bond. Only one of these two alternative modes of binding, that of the isocitrate mode, has been previously visualized. Now, however, the structure revealing the citrate mode of binding provides direct support for the proposed enzyme mechanism.