Conformational changes in the reaction of pyridoxal kinase.
To understand the processes involved in the catalytic mechanism of pyridoxal kinase (PLK),1 we determined the crystal structures of PLK.AMP-PCP-pyridoxamine, PLK.ADP.PLP, and PLK.ADP complexes. Comparisons of these structures have revealed that PLK exhibits different conformations during its catalytic process. After the binding of AMP-PCP (an analogue that replaced ATP) and pyridoxamine to PLK, this enzyme retains a conformation similar to that of the PLK.ATP complex. The distance between the reacting groups of the two substrates is 5.8 A apart, indicating that the position of ATP is not favorable to spontaneous transfer of its phosphate group. However, the structure of PLK.ADP.PLP complex exhibited significant changes in both the conformation of the enzyme and the location of the ligands at the active site. Therefore, it appears that after binding of both substrates, the enzyme-substrate complex requires changes in the protein structure to enable the transfer of the phosphate group from ATP to vitamin B(6). Furthermore, a conformation of the enzyme-substrate complex before the transition state of the enzymatic reaction was also hypothesized.
Li
Ming-Hui
MH
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Kwok
Francis
F
Chang
Wen-Rui
WR
Liu
Sheng-Quan
SQ
Lo
Samuel C L
SC
Zhang
Ji-Ping
JP
Jiang
Tao
T
Liang
Dong-Cai
DC
D000244:Adenosine Diphosphate / Q000737:chemistry; D000249:Adenosine Monophosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology; D002384:Catalysis; D018360:Crystallography, X-Ray; D004583:Electrons; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010710:Phosphates / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D011731:Pyridoxal Kinase / Q000737:chemistry*; D011733:Pyridoxamine / Q000737:chemistry; D012756:Sheep
D010710:Phosphates; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D011733:Pyridoxamine; D000255:Adenosine Triphosphate; D011731:Pyridoxal Kinase