Oxalate Decarboxylase (OxDC) is a bicupin enzyme produced by <i>B. subtilis</i> to degrade mono-protonated oxalate into formate and carbon dioxide. The active site has a flexible loop which allows the substrate to bind to a Mn ion coordinated inside the N-terminal cupin domain. A Mn ion is also coordinated in the C-terminal cupin domain which was initially hypothesized to help form the correct tertiary structure and to assemble the hexamer of the quaternary structure. Dioxygen is a known co-catalyst for OxDC to consume oxalate, however, the role of dioxygen is not well understood. Our research shows that the assembly of a π-stacked pair comprising W96 and W274 away from the active site significantly disturbs the kinetics for decarboxylation of mono-protonated oxalate without perturbing the tertiary structure of OxDC. This was accomplished by mutating the selected tryptophan residues into residues of phenylalanine, tyrosine, and 5-hydroxytryptophan. Data collected from enzyme kinetics, x-ray crystallography, trypsin digested LC-MS/MS peptide analysis, and unnatural amino acid incorporation provides more evidence to re-evaluate the current mechanism of OxDC found in the literature.

Modulation of activity for <i>B. subtilis</i> oxalate decarboxylase by the assembly of a ?-stacked tryptophan residue pair

2019 Spring National Meeting

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Modulation of activity for B. subtilis oxalate decarboxylase by the assembly of a ?-stacked tryptophan residue pair