Characterisitics and Gene Cloning of Phospholipase D of the Psychrophile, Shewanella sp.

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Phospholipase D, with a molecular mass of 64 kDa, was purified from the psychrophile, Shewanella sp. The enzyme showed maximal activity at pH 7.8 and 40 °C in the presence of the Ca²⁺-ion, and its activity at 10 °C was 6.5% of maximum. The enzyme exhibited high activity to the non-micelle form of phosphatidylcholine in an aqueous solution containing water miscible alcohols such as methanol, ethanol, iso-propanol, and n-propanol. Nucleotide sequencing of the enzyme gene yielded a deduced amino acid sequence, which showed 36.2% identity to that of Streptomyces chromofuscus phopsholipase D alone. The low sequence similarity to other phopsholipase D enzymes suggests that the purified enzyme might be a novel phospholipase D.