Preliminary characterization of two glucan synthetase preparations and their reaction products from Candida albicans.

Two glucan synthetase preparations from Candida albicans were obtained by lysis of regenerating protoplasts (enzyme A) or mechanical breakage of yeast cells (enzyme B). Enzyme A was insensitive to EDTA or GTP but it was stimulated by a combination of both agents. Enzyme B was inhibited by EDTA, this inhibition being released by increasing the concentration of the chelating agent or by addition of GTP to the assay mixtures. Enzyme A was further activated by glycerol and sodium fluoride. The reaction products were characterized as linear beta-1,3-linked glucans on the basis of their resistance to periodate and susceptibility to beta-glucanases. In both cases the "in vitro" synthesized radioactive chains were added to the non-reducing end of cold, performed glucan or to and acceptor other than glucan. At least, part of the preformerd glucan chains of enzyme A, but no those of enzyme B, showed a free reducing terminal. On the basis of the origin of both enzyme preparations it is suggested that glucan molecules are synthesized while bound to an acceptor of a different nature which is subsequently excised.