Isolation and characterization of an intracellular aminopeptidase from the extreme thermophilic archaebacterium Sulfolobus solfataricus.
An intracellular aminopeptidase (EC 3.4.11.-) was purified from the extreme thermophilic archaebacterium, Sulfolobus solfataricus. The molecular weight of the native enzyme was about 320,000, as calculated by gel-filtration studies, and a subunit Mr of 80,000 was estimated by SDS-polyacrylamide gel electrophoresis. The temperature optimum of the enzyme was at 75 degrees C and the pH optimum was found to be 6.5. The aminopeptidase was highly active against the chromogenic substrates L-Leu-p-NA and L-Ala-p-NA. The enzyme was inhibited by EDTA, but the activity could be partially restored by removal of the EDTA and incubation with Co2+ or Mn2+. Bestatin, a typical inhibitor of aminopeptidase, fully inhibited the enzyme activity, but inhibitors of serine proteinases had no effect. Beside a high thermostability, the enzyme showed a remarkable stability against 6 M urea, organic solvents and acetonitrile.
Hanner
M
M
Institute of Microbiology, Medical School, University of Innsbruck, Austria.
Redl
B
B
Stöffler
G
G
D000626:Aminopeptidases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D001105:Archaea / Q000201:enzymology*; D001419:Bacteria / Q000201:enzymology*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007526:Isoelectric Point; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature
D010450:Endopeptidases; D000626:Aminopeptidases