Biochemical studies of soluble and immobilized aldehyde dehydrogenase from yeast

Aldehyde dehydrogenase from baker’s yeast was purified to homogeneity. The soluble and immobilized forms of this enzyme were characterized and compared biochemically. These included steady state kinetics, stability study, fluorescence, and NMR spectroscopy. Evidence of the coenzyme binding to this enzyme in the absence of aldehyde substrates was obtained by fluorescence and NMR studies. A significant quenching of protein fluorescence was observed upon the addition of coenzymes to the aldehyde-free enzyme solution. Significant shifts and broadening of coenzyme proton resonances in the presence of enzyme also indicate the enzyme-coenzyme interactions in the aldehyde-free solution. the enzyme was immobilized on glass beads by three different methods. The immobilized enzyme was found to exhibit physical and biochemical properties similar to those of the soluble enzyme. A system in which the immobilized alcohol, aldehyde, and steriod dehydrogenases are included in an enzyme reactor is described.