Esterase that removes acetyl groups from a number of O-acetylated small substrates, such as acetylated xylose, short xylo-oligosaccharides and cephalosporin C. Has no activity towards polymeric acetylated xylan, 4-methylumbelliferyl acetate or alpha-naphthyl acetate. Able to catalyze rapid hydrolysis of a range of substrates preferably with acetate groups, independent of the alcohol moiety. Exhibits a narrow selectivity for short chain acyl esters (C2-C3). Displays broad substrate specificity by hydrolyzing acetate at 2, 3, and 4 positions of 4-nitrophenyl-beta-D-xylopyranoside (pNP-Xyl) with similar efficiency. Cannot cleave amide linkages. Deacetylation of xylans and xylo-oligosaccharides. cephalosporin C + H2O = acetate + deacetylcephalosporin C + H(+) Activity stimulated by up to 40% in the presence of divalent cations such as BaCl(2), CaCl(2), MgCl(2) and MnCl(2) at 3 mM concentration, but inhibited by 82-85% in the presence of CdCl(2) and ZnCl(2) at 3 mM concentration. Optimum pH is 6.5. Half-maximal activity between pH 5.0-7.5. Optimum temperature is 90 degrees Celsius. Activity drops sharply above 90 degrees Celsius. Stable up to 100-104 degrees Celsius. Homohexamer, formed by a trimer of dimers. Also exists as a homodimer. Belongs to the carbohydrate esterase 7 family.