Structure and catalytic mechanism of LigI: insight into the amidohydrolase enzymes of cog3618 and lignin degradation.

ABSTRACT: LigI from Sphingomonas paucimobilis catalyzes the reversible hydrolysis of 2-pyrone-4,6-dicarboxylate (PDC) to 4-oxalomesaconate and 4-carboxy-2-hydroxymuconate in the degradation of lignin. This protein is a member of the amidohydrolase superfamily of enzymes. The protein was expressed in Escherichia coli and then purified to homogeneity. The purified recombinant enzyme does not contain bound metal ions, and the addition of metal chelators or divalent metal ions to the assay mixtures does not affect the rate of product formation. This is the first enzyme from the amidohydrolase superfamily that does not require a divalent metal ion for catalytic activity. The kinetic constants for the hydrolysis of PDC are 340 s(-1) and 9.8 × 10(6) M(-1) s(-1) (k(cat) and k(cat)/K(m), respectively). The p

SUBMITTER: Hobbs ME 

PROVIDER: S-EPMC3416963 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature