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Role of key residues of obelin in coelenterazine binding and conversion into 2-hydroperoxy adduct

Paper ID Volume ID Publish Year Pages File Format Full-Text
30333 44469 2013 7 PDF Available
Title
Role of key residues of obelin in coelenterazine binding and conversion into 2-hydroperoxy adduct
Abstract

•Coelenterazine binding and kinetics of active obelin formation are studied.•Tyr138, His175, Trp179, and Tyr190 are all important for coelenterazine activation.•The proper hydrogen bond network over coelenterazine is required for its activation.•His175 might serve as a proton shuttle during 2-hydroperoxycoelenterazine formation.

Bioluminescence of a variety of marine organisms is caused by monomeric Ca2+-regulated photoproteins, to which a peroxy-substituted coelenterazine, 2-hydroperoxycoelenterazine, is firmly bound. From the spatial structure the side chains of Tyr138, His175, Trp179, and Tyr190 of obelin are situated within the substrate-binding pocket at hydrogen bond distances with different atoms of the 2-hydroperoxycoelenterazine. Here we characterized several obelin mutants with substitutions of these residues regarding their bioluminescence, coelenterazine binding, and kinetics of active obelin formation. We demonstrate that Tyr138, His175, Trp179, and Tyr190 are all important for coelenterazine activation; substitution of any of these residues leads to significant decrease of the apparent reaction rate. The hydrogen bond network formed by Tyr138, Trp179 and Tyr190 participates in the proper positioning of coelenterazine in the active site and subsequent stabilization of the 2-hydroperoxy adduct of coelenterazine. His175 might serve as a proton shuttle during 2-hydroperoxycoelenterazine formation.

Keywords
Bioluminescence; Coelenterazine; Obelin; Aequorin; Photoprotein
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Role of key residues of obelin in coelenterazine binding and conversion into 2-hydroperoxy adduct
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 127, 5 October 2013, Pages 133–139
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us