title: A specific L-asparaginase from Thermus aquaticus.
abstract: The L-asparaginase from an extreme thermophile, Thermus aquaticus strain T351, was highly substrate- and stereospecific, with no activity against glutamine or D-asparagine. It had a high Km of 8.6 mM. In these aspects it closely resembled the corresponding enzymes from thermophilic bacteria. The enzyme had a molecular weight of 80,000, an isoelectric point of 4.6, and a pH optimum of 9.5. It showed some substrate inhibition above 20 mM asparagine and was also inhibited by L-aspartic acid, D- and L-lysine (Ki of 5.2 and 1.25 mM, respectively), and D- and L-serine. The half-life of the enzyme at 85 degrees C was 40 min. The Arrhenius plot showed a change in slope at 55 degrees C.
mesh_terms: D001215:Asparaginase / Q000032:analysis* / Q000302:isolation & purification; D001224:Aspartic Acid / Q000494:pharmacology; D006358:Hot Temperature; D007700:Kinetics; D008239:Lysine / Q000494:pharmacology; D008970:Molecular Weight; D013824:Thermus / Q000201:enzymology*
chemical_list: D001224:Aspartic Acid; D001215:Asparaginase; D008239:Lysine