title: Control of the Position of Oxygen Delivery in Soybean Lipoxygenase-1 by Amino Acid Side Chains within a Gas Migration Channel.
abstract: Understanding gas migration pathways is critical to unraveling structure-function relationships in enzymes that process gaseous substrates such as O2, H2, and N2 This work investigates the role of a defined pathway for O2 in regulating the peroxidation of linoleic acid by soybean lipoxygenase 1. Computational and mutagenesis studies provide strong support for a dominant delivery channel that shuttles molecular oxygen to a specific region of the active site, thereby ensuring the regio- and stereospecificity of product. Analysis of reaction kinetics and product distribution in channel mutants also reveals a plasticity to the gas migration pathway. The findings show that a single site mutation (I553W) limits oxygen accessibility to the active site, greatly increasing the fraction of substrate that reacts with oxygen free in solution. They also show how a neighboring site mutation (L496W) can result in a redirection of oxygen toward an alternate position of the substrate, changing the regio- and stereospecificity of peroxidation. The present data indicate that modest changes in a protein scaffold may modulate the access of small gaseous molecules to enzyme-bound substrates.
authors: From the Department of Molecular and Cell Biology, Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720.
authors: Lara
authors: L
authors: Collazo
authors: From the Department of Molecular and Cell Biology, Department of Chemistry, and the California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720 klinman@berkeley.edu.
authors: Judith P
authors: JP
authors: Klinman
mesh_terms: D019943:Amino Acid Substitution; D008084:Lipoxygenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D030262:Soybean Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics
chemical_list: D030262:Soybean Proteins; D008084:Lipoxygenase; D010100:Oxygen
keywords: catalysis; enzyme mechanism; enzyme mutation; kinetics; lipoxygenase; oxygen channel; protein structure; regio- and stereospecificity