AN ASPERGILLUS-AWAMORI ACETYLESTERASE - PURIFICATION OF THE ENZYME, AND CLONING AND SEQUENCING OF THE GENE

An inducible acetylesterase was purified from the culture medium of As pergillus awamori strain IFO4033 growing on wheat-bran culture by ion- exchange, gel-filtration and hydrophobic-interaction chromatographies. The purified enzyme had an M-r of 31000 and contained Asn-linked olig osaccharides. The enzyme liberated acetic acid from wheat bran, hydrol ysed only alpha-naphthyl acetate and propionate when aromatic esters w ere used for the substrate, and was tentatively classified as a carbox ylic esterase (EC 3.1.1.1). The gene encoding acetylesterase was clone d and sequenced. The deduced amino acid sequence showed that acetylest erase was produced as a 304-amino-acid-residue precursor, which was co nverted post-translationally into a 275-amino-acid-residue mature prot ein. Part of the sequence of acetylesterase was similar to the region near the active-site serine of lipases of Geotrichum candidum and Cand ida cylindracea. A unique site of putative Asn-linked oligosaccharides was presented.