Abstract
Reduction of triphenyltetrazolium chloride by corn embryo homogenates is catalyzed by malic, alcohol, beta-hydroxybutyric, glutamic, and probably also triosephosphate, isocitric, and glycerophosphate dehydrogenases. These systems are linked through diphosphopyridine-nucleotide and diaphorase. Xanthine oxidase (milk) is also active. Optimum conditions and kinetics of the malic system were studied and tetrazolium and methylene blue reduction with a number of substrates was compared.