Studies on the oligomeric structure of yeast aldehyde dehydrogenase by cross-linking with bifunctional reagents

The molecular w:ight of yeast aldehyde dehydrogenase determined by sucrose density gradient centrifugation was 207,000 +/- 13,000. The enzyme activity was proportional to the enzyme concentration in the range of 2 X 10(-11) M to 1 X 10(-7) M. Cross-linking patterns obtained with yeast aldehyde dehydrogenase after treatment with a series of diimidoesters of increasing chain lengths with different reaction times resulted in the appearance of tetramers as the largest cross-linked product of the enzyme subunits. The molecular weights of its monomer, dimer, trimer, and tetramer were, 57,000, 114,000, 171,000, and 228,000, respectively, as estimated from their mobilities on SDS-electrophoresis. In tetramers monomers are probably assembled in a heterologous square arrangement.