5CTS

PROPOSED MECHANISM FOR THE CONDENSATION REACTION OF CITRATE SYNTHASE. 1.9-ANGSTROMS STRUCTURE OF THE TERNARY COMPLEX WITH OXALOACETATE AND CARBOXYMETHYL COENZYME A

Summary for 5CTS

• Entry DOI: 10.2210/pdb5cts/pdb
• Descriptor: CITRATE SYNTHASE, OXALOACETATE ION, CARBOXYMETHYL COENZYME *A, ... (4 entities in total)
• Functional Keywords: oxo-acid-lyase
• Biological source: Gallus gallus (chicken)
• Cellular location: Mitochondrion matrix: P23007
• Total number of polymer chains: 1
• Total formula weight: 48278.81

Authors

Karpusas, M.,Branchaud, B.,Remington, S.J. (deposition date: 1989-11-16, release date: 1990-10-15, Last modification date: 2024-03-06)

Primary citation

Karpusas, M.,Branchaud, B.,Remington, S.J.
Proposed mechanism for the condensation reaction of citrate synthase: 1.9-A structure of the ternary complex with oxaloacetate and carboxymethyl coenzyme A.
Biochemistry, 29:2213-2219, 1990

PubMed Abstract: The crystal structure of the ternary complex citrate synthase-oxaloacetate-carboxymethyl coenzyme A has been solved to a resolution of 1.9 A and refined to a conventional crystallographic R factor of 0.185. The structure resembles a proposed transition state of the condensation reaction and suggests that the condensation reaction proceeds through a neutral enol rather than an enolate intermediate. A mechanism for the condensation reaction is proposed which involves the participation of three key catalytic groups (Asp 375, His 274, and His 320) in two distinct steps. The proposed mechanism invokes concerted general acid-base catalysis twice to explain both the energetics of the reaction and the experimentally observed inversion of stereochemistry at the attacking carbon atom.

PubMed: 2337600
DOI: 10.1021/bi00461a002

Experimental method

X-RAY DIFFRACTION (1.9 Å)