Enzymatic properties of α-amylase from sea urchin, Strongylocentrotus nudas

α-Amylase from the digestive tube of sea urchin, Strongylocentrotus nudas, was isolated by acetone powder, ammonium sulfate fractionation and ion exchange chromatography. Optimum pH of the α-amylase was ∼7.3 in 50 mM NaCl and ∼6.0 in the absence of NaCl at 30°C. Chloride ions activate amylolytic activity in addition to causing a shift of the optimum pH; the K d value was 2.4 mM at 30°C. The action pattern of a-amylase using amylose as a substrate showed a multiple attack mechanism similar to porcine pancreatic α-amylase. Enzymatic properties of α-amylase from the sea urchin were nearly the same as those of mammalian α-amylases, although the digestive organs are still not fully evolved.