Sulfur incorporation into the alpha-amylase of Pseudomonas saccharophila.

Studies by Rotman and Spiegelman (1954) and Hogness et al. (1955) on the 3-galactosidase of Escherichia coli have revealed that virtually all of the carbon and sulfur of that enzyme is derived from exogenous sources when cells are induced during growth. These investigations have thus ruled out the direct participation of a specific preformed precursor in the formation of fl-galactosidase in growing cultures of this organism. In more recent experiments on the biosynthesis of the extracellular a-amylase2 of Pseudomonas saccharophila, it was shown (Markovitz and Klein, 1955b) that growing cells utilize exogenous sources of carbon for enzyme synthesis, in a manner analogous to the 13-galactosidase system. However, resting cell suspensions of P. saccharophila were able to form significant quantities of enzyme and, under such conditions, used largely cellular carbon for enzyme formation. The present investigation represents a confirmation and extension of these earlier observations. In this work, the kinetics of the incorporation of exogenous sulfate into enzyme protein was followed using cells induced in complete medium and in buffer.