Biochemical characterization of deblocking aminopeptidase from hyperthermophilic archaeon Thermococcus onnurineus NA1.
A genomic analysis of the hyperthermophilic archaeon Thermoccoccus onnurineus NA1 (TNA1) revealed the presence of a deblocking aminopeptidase (DAP) gene with high similarity to the genes of DAPs from Pyrococcus furiosus (86%) and Pyrococcus horikoshii (83% identity). The optimum aminopeptidase activity of the recombinant enzyme was observed at pH 7.5 and in the range of 90 degrees C to 100 degrees C. The specific aminopeptidase and deblocking activities of the enzyme toward Leu-pNA and Ac-Leu-pNA were 18- and 3-fold higher than those of a P. horikoshii DAP (DAP2), respectively. The enzyme activity was significantly increased by Co(2+) ions. The presence of Co(2+) ions induced the activation of the enzyme with heating and changed the large oligomer to a dimer. The enzyme activated by Co(2+) ions appeared to eventually be inactivated by autodegradation, which was confirmed by mass spectrometry.
Lee
Hyun Sook
HS
Korea Ocean Research & Development Institute, Ansan P.O. Box 29, Seoul 425-600, Korea.
Cho
Yona
Y
Kim
Yun Jae
YJ
Nam
Kwanghyun
K
Lee
Jung-Hyun
JH
Kang
Sung Gyun
SG
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D013045:Species Specificity; D013379:Substrate Specificity; D019712:Thermococcus / Q000145:classification / Q000201:enzymology*
D000626:Aminopeptidases