2bfc

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spinqualitylabelsall models 2bfc, resolution 1.64Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

REACTIVITY MODULATION OF HUMAN BRANCHED-CHAIN ALPHA-KETOACID DEHYDROGENASE BY AN INTERNAL MOLECULAR SWITCH

Overview

The dehydrogenase/decarboxylase (E1b) component of the 4 MD human, branched-chain alpha-ketoacid dehydrogenase complex (BCKDC) is a thiamin, diphosphate (ThDP)-dependent enzyme. We have determined the crystal, structures of E1b with ThDP bound intermediates after decarboxylation of, alpha-ketoacids. We show that a key tyrosine residue in the E1b active, site functions as a conformational switch to reduce the reactivity of the, ThDP cofactor through interactions with its thiazolium ring. The, intermediates do not assume the often-postulated enamine state, but likely, a carbanion state. The carbanion presumably facilitates the second, E1b-catalyzed reaction, involving the transfer of an acyl moiety from the, intermediate to a lipoic acid prosthetic group in the transacylase (E2b), component ... [(full description)]

About this Structure

2BFC is a [Protein complex] structure of sequences from [Homo sapiens] with K, MN, TZD and GOL as [ligands]. Active as [3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring)], with EC number [1.2.4.4]. Structure known Active Site: AC1. Full crystallographic information is available from [OCA].

Reference

A versatile conformational switch regulates reactivity in human branched-chain alpha-ketoacid dehydrogenase., Machius M, Wynn RM, Chuang JL, Li J, Kluger R, Yu D, Tomchick DR, Brautigam CA, Chuang DT, Structure. 2006 Feb;14(2):287-98. PMID:16472748

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