MOLECULAR CHARACTERISTICS OF YEAST ALDOLASE

The preparation of a stable crystalline yeast fructose diphosphate aldolase has allowed the study of the molecular properties of this class II aldolase. Isoelectric fractionation shows the presence of three enzymatically active components each exhibiting similar molecular properties. Ultracentrifugal experiments demonstrate these molecules have a molecular weight of 80,000 ± 2,000 g/mole. In the presence of 6 m guanidine hydrochloride and 0.1 m 2-mercaptoethanol (or in acid solution), the molecule dissociates into two subunits which have molecular weights of 40,000 ± 1,000 g/mole. Yeast aldolase may be reconstituted from an acid solution of monomers to yield an enzymatically active preparation which is principally dimeric. The metal ion is not necessary for the stabilization of the dimeric structure of yeast aldolase, but is essential for enzymatic activity. The similarities in subunit size and amino acid compositions of yeast aldolase and the rabbit aldolases suggest a structural relationship. © 1969, American Chemical Society. All rights reserved.