Penicillin Gacylase in one of the most important enzymes, it belonging to __ampersandsignbeta;-lactam antibiotics, first report on the enzyme penicillin acylase was in 1950 when they found in the mycelium of a Penicillium sp. The enzyme appeared to be a periplasmaticheterodimeric N-terminal serinehydrolase with a molecular mass of 86,183 Da, with a 23,817 Da (209 amino acids)__ampersandsignalpha;-subunit and a 62,366 Da (566 amino acids) __ampersandsignbeta;-subunit. This enzyme is capable of hydrolyzing penicillin G into phenyl acetic acid and 6-aminopenicillanic acid (6-APA) so this enzyme isthe starting material for the manufacture of penicillin derivatives, which are the most widely used __ampersandsignbeta;-lactam antibiotics. Both natural and semi-synthetic penicillins contain 6-aminopenicillanic acid.