Christen P, Gasser A
Eur J Biochem. 1980;107(1):73-7. doi: 10.1111/j.1432-1033.1980.tb04626.x.
In the presence of hexacyanoferrate(III), or other suitable oxidants, transketolase catalyzes the oxidative cleavage of its donor substrates xylulose 5-phosphate or fructose 6-phosphate into glycolate and glyceraldehyde 3-phosphate or erythrose 4-phosphate, respectively. Two moles of hexacyanoferrate(III) are reduced per mole of oxidatively cleaved donor substrate. In analogy to the oxidative trapping of carbanion intermediates of other enzymes [Healy, M. J. & Christen, P. (1973) Biochemistry, 12, 35-41], the kinetic features of the reaction indicate that the 1,2-dihydroxyethylthiamin diphosphate intermediate is the oxidation-susceptible species. The molecular activity for the oxidative cleavage of fructose 6-phosphate at a hexacyanoferrate(III) concentration of 0.5 mM is 0.2% of that for the normal transfer reaction with erythrose 4-phosphate as acceptor substrate. Glycolate is also produced with H2O2 as oxidant; however, the reaction is at least two orders of magnitude slower than with hexacyanoferrate(III).
在高铁氰化钾或其他合适的氧化剂存在下，转酮醇酶催化其供体底物5-磷酸木酮糖或6-磷酸果糖分别氧化裂解为乙醇酸和3-磷酸甘油醛或4-磷酸赤藓糖。每摩尔被氧化裂解的供体底物会使两摩尔高铁氰化钾被还原。与其他酶的碳负离子中间体的氧化捕获类似[希利，M. J. & 克里斯滕，P.（1973年）《生物化学》，12卷，35 - 41页]，该反应的动力学特征表明1,2 - 二羟乙基硫胺二磷酸中间体是易被氧化的物种。在高铁氰化钾浓度为0.5 mM时，6-磷酸果糖氧化裂解的分子活性是与4-磷酸赤藓糖作为受体底物的正常转移反应的0.2%。以过氧化氢作为氧化剂时也会产生乙醇酸；然而，该反应比用高铁氰化钾时至少慢两个数量级。
