Churchich J E, Scholz G, Kwok F
Department of Biochemistry, University of Tennessee, Knoxville 37916.
Biochem Int. 1988 Sep;17(3):395-403.
Pyridoxal kinase displays high catalytic activity in the presence of metallothionein. The apoprotein of metallothionein as well as the peptide LYS-CYS-THR-CYS-CYS-ALA exert a strong inhibitory effect upon pyridoxal kinase by sequestering free Zn ions. Several steps intervene in the process of pyridoxal kinase activation, i.e. binding of Zn ions by ATP and interaction of Zn-ATP with the enzyme; but direct interaction between metallothionein and pyridoxal kinase (protein association) could not be detected by emission anisotropy measurements. Since the concentration of free Zn++ in mammalian tissues is lower than 10(-9)M, it is postulated that the concentration of metallothionein regulates the catalytic activity of pyridoxal kinase. The mechanism of reconstitution of the metalloenzyme yeast aldolase in the presence of metallothionein was also investigated.
在金属硫蛋白存在的情况下，吡哆醛激酶表现出高催化活性。金属硫蛋白的脱辅基蛋白以及肽LYS-CYS-THR-CYS-CYS-ALA通过螯合游离锌离子对吡哆醛激酶产生强烈的抑制作用。吡哆醛激酶激活过程中有几个步骤，即ATP与锌离子结合以及锌-ATP与酶相互作用；但通过发射各向异性测量未检测到金属硫蛋白与吡哆醛激酶之间的直接相互作用（蛋白质缔合）。由于哺乳动物组织中游离Zn++的浓度低于10^(-9)M，因此推测金属硫蛋白的浓度调节吡哆醛激酶的催化活性。还研究了在金属硫蛋白存在下金属酶酵母醛缩酶的重组机制。
