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2bk5
From Proteopedia
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Revision as of 18:57, 12 November 2007
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HUMAN MONOAMINE OXIDASE B: I199F MUTANT IN COMPLEX WITH ISATIN
Overview
Several reversible inhibitors selective for human monoamine oxidase B (MAO, B) that do not inhibit MAO A have been described in the literature. The, following compounds: 8-(3-chlorostyryl)caffeine, 1,4-diphenyl-2-butene, and trans,trans-farnesol are shown to inhibit competitively human, horse, rat, and mouse MAO B with K(i) values in the low micromolar range but are, without effect on either bovine or sheep MAO B or human MAO A. In, contrast, the reversible competitive inhibitor isatin binds to all known, MAO B and MAO A with similar affinities. Sequence alignments and the, crystal structures of human MAO B in complex with 1,4-diphenyl-2-butene or, with trans,trans-farnesol provide molecular insights into these, specificities. These inhibitors span the substrate and entrance cavities, with the side chain of Ile-199 rotated out of its normal conformation, suggesting that Ile-199 is gating the substrate cavity. Ile-199 is, conserved in all known MAO B sequences except bovine MAO B, which has Phe, in this position (the sequence of sheep MAO B is unknown). Phe is, conserved in the analogous position in MAO A sequences. The human MAO B, I199F mutant protein of MAO B binds to isatin (K(i) = 3 microM) but not to, the three inhibitors listed above. The crystal structure of this mutant, demonstrates that the side chain of Phe-199 interferes with the binding of, those compounds. This suggests that the Ile-199 "gate" is a determinant, for the specificity of these MAO B inhibitors and provides a molecular, basis for the development of MAO B-specific reversible inhibitors without, interference with MAO A function in neurotransmitter metabolism.
About this Structure
2BK5 is a Single protein structure of sequence from Homo sapiens with FAD and ISN as ligands. Active as Amine oxidase (flavin-containing), with EC number 1.4.3.4 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
Reference
Demonstration of isoleucine 199 as a structural determinant for the selective inhibition of human monoamine oxidase B by specific reversible inhibitors., Hubalek F, Binda C, Khalil A, Li M, Mattevi A, Castagnoli N, Edmondson DE, J Biol Chem. 2005 Apr 22;280(16):15761-6. Epub 2005 Feb 14. PMID:15710600
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