Purification and Characterization of Thermostable Maltooligosyl Trehalose Trehalohydrolase from the Thermoacidophilic Archaebacterium Sulfolobus acidocaldarius

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A thermostable maltooligosyl trehalose trehalohydrolase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius ATCC 33909 was purified from a cell-free extract to an electrophoretically pure state by successive column chromatographies on Sepabeads FP-DA13, Butyl-Toyopearl 650M, DEAE-Toyopearl 650S, Toyopearl HW-55S and Ultrogel AcA44. The enzyme had a molecular mass of 59, 000 by SDS-polyacrylamide gel electrophoresis and a pl of 6.1 by gel isoelectrofocusing. The N-terminal amino acid of the enzyme was methionine. The enzyme showed the highest activity from pH 5.5 to 6.0 and at 75°C, and was stable from pH 5.5 to 9.5 and up to 85°C. The activity was inhibited by Hg⁶<2+>, Cu²⁺, Fe²⁺, Pb²⁺, and Zn²⁺. The K_m values of the enzyme for maltosyl trehalose, maltotriosyl trehalose, maltotetraosyl trehalose, and maltopentaosyl trehalose were 16.7 mM, 2.7 mM, 3.7 mM, and 4.9 mM, respectively.