Enzymatic properties of the N- and C-terminal halves of human hexokinase II.
Although previous studies on hexokinase (HK) II indicate both the N- and C-terminal halves are catalytically active, we show in this study the N-terminal half is significantly more catalytic than the C-terminal half in addition to having a significantly higher Km for ATP and Glu. Furthermore, truncated forms of intact HK II lacking its first N-terminal 18 amino acids (delta18) and a truncated N-terminal half lacking its first 18 amino acids (delta18N) have higher catalytic activity than other mutants tested. Similar results were obtained by PET-scan analysis using (18)FFDG. Our results collectively suggest that each domain of HK II possesses enzyme activity, unlike HK I, with the N-terminal half showing higher enzyme activity than the C-terminal half.
Ahn
Keun Jae
KJ
Division of Nuclear Medicine, Department of Diagnostic Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul 120-752, Korea.
Kim
Jongsun
J
Yun
Mijin
M
Park
Jeon Han
JH
Lee
Jong Doo
JD
D002384:Catalysis; D020134:Catalytic Domain; D006593:Hexokinase / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D050505:Mutant Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D014407:Tumor Cells, Cultured
D007527:Isoenzymes; D050505:Mutant Proteins; D006593:Hexokinase