Purification and characterization of 3-isopropylmalate dehydrogenase from a thermoacidophilic archaebacterium Sulfolobus sp. strain 7 |
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Authors: | Emiri Yoda Yoriko Anraku Hiromi Kirino Takayoshi Wakagi Tairo Oshima |
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Institution: | Department of Life Science, Tokyo Institute of Technology, Midori-ku, Nagatsuta, Yokohama 226, Japan |
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Abstract: | Abstract 3-Isopropylmalate dehydrogenase was purified (about 2000-fold) to homogeneity for the first time from an archaebacterium, Sulfolobus sp. strain 7. The enzyme showed an apparent molecular mass of about 110 kDa by gel filtration and a single 36-kDa polypeptide band on SDS-PAGE, suggesting tri- or tetrameric structure. The p I value was 6.9. The N-terminal amino acid sequence was similar to enzymes from other sources. The enzyme activity was greatly stimulated by the presence of Mn2+, Cd2+, Mg2+, or Co2+. In contrast to 3-isopropylmalate dehydrogenase from other sources, monovalent cations such as K2+ and Na2+ were neither essential for activity nor stability of the protein. The enzyme was extraordinarily thermostable. |
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Keywords: | Archaebacterium Sulfolobus 3-Isopropylmalate dehydrogenase |
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