Yoshiharu Matahira

Regioselectivity of β-d-galactosyl-disaccharide formation using the β-d-galactosidase from Bacillus circulans

Abstract β- d -Galactosidase from Bacillus circulans catalyzed the transfer of galactose from lactose predominantly to the OH-4 position of, respectively, GlcNAc and GalNAc to afford β -d-Gal-(1 → 4)-d-GlcNAc and β -d-Gal-(1 → 4)-d-GalNAc. Thus, preponderant formation of (1 → 4)-linkages occurs and (1 → 6)-linkages are formed to a lesser extent, but no (1 → 3)- or (1 → 1)-linkages are formed. When 3-acetamido-3-deoxy- d -glucose (Glc3NAc, N -acetylkanosamine) was used as an acceptor, the enzyme catalyzed the β- d -galactosyl transfer to, respectively, the β-anomeric position (OH-1) and OH-6 of this sugar to afford β , β -d-Gal-(1 → 1)-d-Glc3NAc and β -d-Gal-(1 → 6)-d-Glc3NAc. In contrast, with methyl β- d -glucoside and methyl β- d -galactoside as acceptors, the enzyme induced the formation of (1 → 3)-linked disaccharide glycoside other than (1 → 4)- and (1 → 6)-linked ones. This demonstrates that the regioselectivity of β- d -galactosyl transfer onto GlcNAc, GalNAc, and Glc3NAc acceptors as catalyzed by the enzyme is strongly determined by the presence of the N -acetyl group.

WATER-SOLUBLE CHITIN OF LOW DEGREE OF DEACETYLATION

It was found that regenerated chitin obtained by a concentrated alkali treatment at a low temperature is water soluble. Chitin with 38% deacetylation, obtained by treatment with 15 wt.% NaOH at 10°C for four days, showed very good solubility in water at room temperature; whereas, eight days at 3°C were needed to prepare soluble chitin with 25% deacetylation. For this low-temperature deacetylation, two conditions were necessary to make α-chitin water soluble; first, an extended alkali treatment (e.g., at least four days in 15% alkali solution at 3°C) was required; and second, the degree of deacetylation required was more than 25%. The structural difference in regenerated chitin samples prepared at 3 and 25°C with the same degree of deacetylation (30%) were examined by X-ray diffraction and deamination analyses suggesting that the distribution of N-acetyl groups in the former chitin molecule was more random than those in the latter. This conclusion was supported by enzymatic analyses with chitinase or lysozyme.

Enzymic synthesis of lacto-N-triose II and its positional analogues

N-acetylhexosaminidase fromNocardia orientalis catalysed the synthesis of lacto-N-triose II glycoside (β-d-GlcNAc-(1-3)-β-d-Gal-(1-4)-β-d-Glc-OMe,3) with its isomers β-d-GlcNAc-(1-6)-β-d-Gal-(1-4)-β-d-Glc-OMe (4) and β-d-Gal-(1-4)-[β-d-GlcNAc-(1-6)]-β-d-Glc-OMe (5) throughN-acetylglucosaminyl transfer fromN,N′-diacetylchitobiose (GlcNAc2) to methyl β-lactoside. The enzyme formed the mixture of trisac-charides3, 4 and5 in 17% overall yield based on GlcNAc2, in a ratio of 20:21:59. Withp-nitrophenyl β-lactoside as an acceptor, the enzyme also producedp-nitrophenyl β-lacto-N-trioside II (β-d-GlcNAc-(1-3)-β-d-Gal-(1-4)-β-d-Glc-OC6H4NO2-p,6) with its isomers β-d-GlcNAc-(1-6)-β-d-Gal-(1-4)-β-d-Glc-OC6H4NO2-p (7) and β-d-Gal-(1-4)-[β-d-GlcNAc-(1-6)]-β-d-Glc-OC6H4NO2-p (8). In this case, when an inclusion complex ofp-nitrophenyl lactoside acceptor with β-cyclodextrin was used, the regioselectivity of glycosidase-catalysed formation of trisaccharide glycoside was substantially changed. It resulted not only in a significant increase of the overall yield of transfer products, but also in the proportion of the desired compound6.

Osteoclast-forming suppressive compounds from Makomotake, Zizania latifolia infected with Ustilago esculenta

A novel compound (1) and a known one (2) were isolated from Makomotake, Zizania latifolia infected with Ustilago esculenta, as osteoclast-forming suppressive substances.

N-Acetylglucosaminyl Disaccharide and Trisaccharide Formation Through Lysozyme-Catalyzed Transfer Reaction

Abstract A hen egg-white lysozyme produced regioselectively 4-O-(2-acetamido–2-deoxy-β-D-glucopyranosyl)-D-mannose and p-nitrophenyl 4-O-(2-acet-amido–2-deoxy-β-D-glucopyranosyl)-β-D-mannopyranoside through a transglycosylation reaction from N,N′-diacetylchitobiose and respectively mannose and p-nitrophenyl β-D-mannopyranoside. These enzyme reactions were efficient enough to allow the one-pot preparation of the desired disaccharide. When p-nitrophenyl 2-acetamido-2-deoxy-α-D-glucopyranoside was the acceptor, the enzyme catalyzed the formation of a β-(1–3)-linked disaccharide glycoside (p-nitrophenyl 2-acetamido-2-deoxy-3-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl) α-D-glucopyranoside) with its β-(1–4)-linked isomer. This is also the case for the formation of p-nitrophenyl 3-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-maltoside with p-nitrophenyl α-maltoside acceptor. The results show that the anomeric configuration of the glycosidic linkage in the glycosyl acceptors had a pronounced effect on the position...

Separation and physiological functions of anserine from fish extract

Abstract A separation process that produces anserine powder with a 10.6 % purity and a 9 % yield from the raw material bonito extract was established. This powder was further purified to anserine hydrochloride with a purity of 98 %. In tests of its physiological effect, anserine that had been administered orally to mice was quickly absorbed into the blood stream and was found to increase the swimming time and the chinning exercise time of the mice. In addition, the content of lactic acid in plasma was lower in mice given anserine than in mice that had not received the dipeptide. These results suggest that anserine has an anti-fatigue effect. The anti-oxidant effect of anserine in vitro by ESR was investigated: anserine, as well as the other imidazole dipeptide carnosine, showed a strong ability to eliminate hydroxyl radicals and singlet oxygens. On the basis of these interesting properties, anserine was considered to have a potential for use in a wide range of applications, including as a component of functional foods and cosmetics.