Cyclopenase, ein Lipoproteid der Protoplasmamembran von Konidiosporen des Pilzes Penicillium cyclopium WESTLING

Cyclopenase, an enzyme which transforms cyclopenin and cyclopenol to viridicatin and viridicatol respectively under elimination of CO 2 and methylamine is a constituent of the inner side of the protoplasma membrane of the conidiospores of Penicillium cyclopium. This is shown by the following facts. The cell wall‐protoplasma membrane fraction of homogenates contains nearly all the enzyme activity. By surface active agents the membrane‐bound enzyme may be solubilized as a protein‐phospholipid complex. Cyclopenase in vivo is separated from its substrates, which at least partly are deposited in the cell wall of the conidia. By treating the solubilized enzyme‐phospholipid complex with n ‐butanol it is separated into the lipid part and the enzyme protein maintaining a considerable part of its activity. The reaction of cyclopenase in the membrane bound and in the solubilized forms with and without the phospholipid part follows the MICHAELIS‐MENTEN kinetics. Changes of the pH‐optima and K m ‐values indicate an alteration of the catalytic properties of the enzyme during solubilization whereas no differences in this respect were found between the soluble phospholipid complex and the phospholipid‐free enzyme.