Purification and properties of a glucuronan lyase from Sinorhizobium meliloti M5N1CS (NCIMB 40472)

A glucuronan lyase extracted from Sinorhizobium meliloti strain M5N1CS was purified to homogeneity by anion-exchange chromatography. The purified enzy me corresponds to a monomer with a molecular mass of 20 kDa and a pl of 4.9 . A specific activity was found only for polyglucuronates leading to the pr oduction of 4,5-unsaturated oligoglucuronates. The enzyme activity was opti mal at pH 6.5 and 50 degreesC. Zn2+, Cu2+, and Hg2+ (1 mM) inhibited the en zyme activity. No homology of the enzyme N-terminal amino acid sequence was found with any of the previously published protein sequences. This enzyme purified from S. meliloti strain M5N1CS corresponding to a new lyase was cl assified as an endopolyglucuronate lyase.