An eleven amino acid residue deletion expands the substrate specificity of acetyl xylan esterase II (AXE II) from Penicillium purpurogenum

摘要: The soft-rot fungus Penicillium purpurogenum secretes to the culture medium a variety of enzymes related xylan biodegradation, among them three acetyl esterases (AXE I, II and III). AXE has 207 amino acids; it belongs family 5 carbohydrate its structure been determined by X-ray crystallography at 0.9 A resolution (PDB 1G66). enzyme possesses α/β hydrolase fold catalytic triad typical serine (Ser90, His187 Asp175). can hydrolyze esters large alcohols, but is restricted short chain fatty acids. An analysis three-dimensional shows that loop covers active site may be responsible for this strict specificity. Cutinase, an hydrolyzes long acids similar II, lacks loop. In order generate with broader specificity, preparation mutant lacking residues involving (Gly104 Ala114) was proposed. A set molecular simulation experiments based on comparative model predicted stable structure. Using site-directed mutagenesis, loop’s have eliminated from cDNA. protein expressed in Aspergillus nidulans A722 Pichia pastoris, towards range acid up least 14 carbons. availability esterase specificity biotechnological applications synthesis sugar esters.