Mode of action on deacetylation of acetylated methyl glycoside by cellulose acetate esterase from Neisseria sicca SB.
The regioselective deacetylation of purified cellulose acetate esterase from Neisseria sicca SB was investigated on methyl 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside and 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside. The substrates were used as model compounds of cellulose acetate in order to estimate the mechanism for deacetylation of cellulose acetate by the enzyme. The enzyme rapidly deacetylated at position C-3 of methyl 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside to accumulate 2,4,6-triacetate as the main initial reaction product in about 70% yield. Deacetylation was followed at position C-2, and generated 4,6-diacetate in 50% yield. The enzyme deacetylated the product at positions C-4 and C-6 at slower rates, and generated 4- and 6-monoacetates at a later reaction stage. Finally, it gave a completely deacetylated product. For 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside, CA esterase deacetylated at positions C-3 and C-6 to give 2,4,6- and 2,3,4-triacetate. Deacetylation proceeded sequentially at positions C-3 and C-6 to accumulate 2,4-diacetate in 55% yield. The enzyme exhibited regioselectivity for the deacetylation of the acetylglycoside.
Moriyoshi
Kunihiko
K
Department of Environmental Technology, Osaka Municipal Technical Research Institute. moriyosi@omtri.city.osaka.jp
Yamanaka
Hayato
H
Ohmoto
Takashi
T
Ohe
Tatsuhiko
T
Sakai
Kiyofumi
K
D000107:Acetylation; D002265:Carboxylic Ester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D004187:Disaccharides; D005690:Galactose / Q000737:chemistry / Q000378:metabolism; D005965:Glucuronates; D006027:Glycosides / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008757:Methylglucosides / Q000737:chemistry / Q000378:metabolism; D042808:Neisseria sicca / Q000201:enzymology*; D013379:Substrate Specificity; D013997:Time Factors
D004187:Disaccharides; D005965:Glucuronates; D006027:Glycosides; D008757:Methylglucosides; C027020:methylglucoside; C059554:O-(glucuronic acid 2-sulfate)-(1--4)-O-(2,5)-anhydromannitol 6-sulfate; D002265:Carboxylic Ester Hydrolases; C403303:cellulose acetate esterase; D005690:Galactose