Two L-amino Acid Oxidase Isoenzymes from Russell’s Viper (Daboia russelli russelli) Venom with Different Mechanisms of Inhibition by Substrate Analogs
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Two L-amino Acid Oxidase Isoenzymes from Russell’s Viper
(Daboia russelli russelli) Venom with Different Mechanisms
of Inhibition by Substrate Analogs
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| Creator |
Mandal, Somnath
Bhattacharyya, Debasish |
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| Subject |
Structural Biology & Bioinformatics
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| Description |
Two isoforms, L1 and L2, of l-amino acid oxidase have been isolated from Russell’s viper venom by Sephadex G-100 gel filtration followed by CMSephadex C-50 ion exchange chromatography. The enzymes, with different
isoelectric points, are monomers of 60–63 kDa as observed from size exclusion HPLC and SDS⁄PAGE. Partial N-terminal amino acid sequencing of L1 and L2 showed significant homology with other snake venom l-amino acid oxidases. Both the enzymes exhibit marked substrate preference for
hydrophobic amino acids, maximum catalytic efficiency being observed with l-Phe. Inhibition of L1 and L2 by the substrate analogs N-acetyltryptophan and N-acetyl-l-tryptophan amide has been followed. The initial uncompetitive inhibition of L1 followed by mixed inhibition at higher concentrations suggested the existence of two different inhibitor-binding sites distinct from the substrate-binding site. In the case of L2, initial linear competitive inhibition followed by mixed inhibition suggested the existence of two nonoverlapping inhibitor-binding sites, one of which is the substratebinding
site. An inhibition kinetic study with O-aminobenzoic acid, a mimicking substrate with amino, carboxylate and hydrophobic parts, indicated the presence of three and two binding sites in L1 and L2, respectively,
including one at the substrate-binding site. An inhibitor cross-competition kinetic study indicated mutually excluding binding between N-acetyltryptophan,
N-acetyl-l-tryptophan amide and O-aminobenzoic acid in both the isoforms, except at the substrate-binding site of L1. Binding of substrate analogs with different electrostatic and hydrophobic properties provides useful insights into the environment of the catalytic sites. Furthermore, it
predicts the minimum structural requirement for a ligand to enter and anchor at the respective functional sites of LAAO that may facilitate the design of suicidal inhibitors.
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| Date |
2008
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/283/1/FEBS_JOURNAL%2C275(9)%2C_2078%2D2095%2C2008[89].pdf
Mandal, Somnath and Bhattacharyya, Debasish (2008) Two L-amino Acid Oxidase Isoenzymes from Russell’s Viper (Daboia russelli russelli) Venom with Different Mechanisms of Inhibition by Substrate Analogs. FEBS Journal, 275 (9). pp. 2078-2095. |
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| Relation |
http://dx.doi.org/10.1111/j.1742-4658.2008.06362.x
http://www.eprints.iicb.res.in/283/ |
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