A new thermolabile alkaline phospholipase D from <Emphasis Type="Italic">Streptomyces</Emphasis> sp. CS628

A phospholipase D (PLD₆₂₈), constitutively secreted by Streptomyces sp. CS628, was purified by ion exchange with CM Trisacryl and gel filtration with Sepharose CL-6B. The enzyme production was highest with peptone and starch as nitrogen and carbon sources, and at 30°C with an initial medium pH of 7.5. Molecular weight, optimum pH, optimum temperature, pH stability, and thermostability of the enzyme were 50 kDa, pH 9.6, 30°C, pH 5.7 ∼ 10.6 and ≤30°C, respectively. Detergents and metal ions had varied effects on the enzyme activity. Importantly, PLD₆₂₈ could not catalyze transphosphatidylation of glycerol, L-serine, myo-inositol or ethanolamine, which are extensively used to assess the activity, suggesting that PLD₆₂₈ lacks the transphosphatidylation activity. PLD₆₂₈ could be a novel PLD based on its biochemical characteristics, which are significantly different from previously reported PLDs, such as thermolability, highest activity at alkaline pH, and lack of transphosphatidylation activity.