アルコール溶液中での糖転移反応による高級アルコールβ-キシロシドの酵素合成

Among several fungal β-xylosidases, Aspergillus niger β-xylosidase had the highest hydrolytic activity and stability in the presence of water miscible solvents such as acetone and alcohols. The enzvmatic synthesis of alkyl β-xylosides from xylobiose and alcohols through the transxylosylation reaction of the enzyme was studied. Various alkyl β-xylosides were effectively synthesized from xylobiose and water miscible alcohol such as methanol, ethanol and 2-propanol. Water immiscible alcohol such as 1-butanol, 1-hexanol, benzyl alcohol and 2-butanol, also acted as effective acceptors for transxylosyl reaction, where a great part of synthesized β-xylosides were found in the insoluble alcohol layer. Therefore, the synthesized β-xyloside, such as 1-hexyl β-xyloside, could be readily separated from the reaction mixture and crystallized. Xylooligomers and xylan hydrolyzates acted as an effective xylosyl donor. Accumulation factors of alkyl β-xyloside produced enzymatically in the transxylosylation and superiority of Asp. niger β-xylosidase for the enzymatic synthesis of alkyl β-xylosides were also described

Spin Structure Function g2g_2 and Twist-3 Operators in QCD

We investigate the spin structure function $g_2 (x, Q^2 )$ in the framework of the operator product expansion and the renormalization group. The twist-3 operators appearing in QCD are examined and their relations are studied. It is noted that operators proportional to equation of motion appear in the operator mixing through renormalization, which can be studied from the relevant Green's functions. We also note that the coefficient functions can be properly fixed after the choice of independent operators.Comment: LaTeX, 11 pages, KUCP-71; HUPD-941

QCD Corrections to the nucleon's spin structure function G2(x,Q2)G_2(x,Q^2)

We investigate the renormalization of the twist-3 operators which are relevant for the spin-dependent structure function $g_{2}(x, Q^{2})$. We derive the anomalous dimension for the non-singlet part by calculating the off-shell Green's functions of the twist-3 operators including the operators which are proportional to the equation of motion.Comment: 10 pages, LaTeX, 1 Postscript figur

Substrate Specificity of α-L-Arabinofuranosidase from Streptomyces diastatochromogenes 065 toward Arabinose-Containing Oligosaccharides

α-L-Arabinofuranosidase from Streptomyces diastatochromogenes 065 released only the terminal arabinose of arabinoxylo-oligosaccharides. The enzyme hydrolyzed methyl arabinofuranobiosides to arabinose and methyl arabinofuranoside in the order of (1→2)>(1→3)>(1→5)-linkages. The enzyme preferentially hydrolyzed the (1→3)-linkage over the (1→5)-linkage of methyl arabinofuranotrioside

Measurement of β-Mannosidase Activity Using β-1,4-Mannobiose

"Glucose C II - Test Wako" (Glucose Oxidase (GOD) Reagent) reacts glucose well, and is sensitive against xylose and mannose (M_1). Using this reagent and β-1, 4-mannobiose (M_2), Aspergillus niger β-mannosidase activily could be measured. The enzyme hydrolyzed M_2 to produce M_1, and no transfer product was detected in the thin-layer chromatography. Optimal pH of the enzyme using M_2 was measured to be the same around pH 3-4 as using p-nitrophenyl β-D-mannopyranoside (PNPM). The enzyme activity measured by the developed method seemed to be identical with the activity using PNPM as substrate. This result indicate that β-mannosidase activity can be measured by the developed method using M_2 instead of PNPM

Measurement of β-Glucobiose-Hydrolysis Activity and Comparison of Two β-Glucosidases

β-グルコ2糖(G2)とグルコースオキシダーゼ(GOD)試薬を用いることによって、β-グルコシダーゼによるG2からのグルコース(G1)の遊離が測定された。アーモンドエムルシンのβ-グルコシダーゼはG2を加水分解してG1を生成し、転移物の生成は見られなかった。G1の遊離速度はラミナリビオース>ソホロース>セロビオース>ゲンチオビオースの順であった。本酵素はG2よりもp-ニトロフエニルβ-D-グルコシド(PNPG)に対し強い活性を有し、アリルβ-グルコシダーゼと分類されるのが妥当と思われる。一方、放線菌β-グルコシダーゼはアーモンドのものと異なり、トランスグルコシダーゼと呼ぶのが適当と思われる。PNPG分解とGOD試薬を組み合わせることで、上記二種の酵素を比較した。Release of glucose (G1) from β-glucobiose (G2) by β-glucosidase action could be measured using G2 and "Glucose CII-Test Wako" (Glucose Oxidase(GOD) Reagent). Almond Emulsin β-glucosidase hydrolyzed G2 to produce G1, and no transfer product was detected in the thin-layer chromatography. The relative rate liberating G1 from G2 by the enzyme was in the order of laminaribiose> sophorose> cellobiose> gentiobiose. The enzyme had higher hydrolysis activity for p-nitrophenyl β-D-glucoside(PNPG) than for G2, so that it could be called an "aryl β-glucosidase". However, Streptomyces β-glucosidase was different from the enzyme, and could be called a "transglucosidase". Absorption spectra of PNPG-hydrolysis system combined with the GOD reagent was also compared between the two β-glucosidases

Enzymic Degradation of Fucoidan by Fucoidanase from the Hepatopancreas of Patinopecten yessoensis

A fucoidanase from the hepatopancreas of Patinopecten yessoensis was purified by ammonium sulfate precipitation, anion exchange chromatography, isoelectric focusing, and gel chromatography. The purified enzyme gave a single band on polyacrylamide gel electrophoresis. The fucoidanase was practically free from α-L-fucosidase and arylsulfatase activities. The molecular weight of the enzyme was estimated to be 85,000 by gel filtration on TSKgel G3000SW and 84,000 by SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis. The enzyme hydrolyzed fucoidan to produce sulfated oligosaccharides as the reaction products

2種のβ-キシロシダーゼによるキシロースの縮合反応の比較

The kinetic characterization of two fungal (Aspergillus niger and Malbranchea pulchella) β-xylosidases reveals "product specificity" in the condensation reaction of xylose. The specificity of xylodisaccharide production in the condensation reaction yields more variation for the M. pulchella enzyme than for the A. niger one. Of the products, β-1,4-xylodisac-charide is produced most in the reaction of both enzymes. A simple mechanism with forward (condensation) and reverse (hydrolysis) reactions is assumed and the rate constants for the forward reactions of the respective β-linked xylodisaccharides are experimentally determined as well as the equilibrium constants. The rate constants for the reverse reactions are estimated from these equilibrium and rate constants, and found to have smaller values than those observed in the initial velocities of the hydrolysis, inferring inhibition of the reaction with a high concentration of xylose. Comparison of the actual time course in xylodisaccharide production with that obtained by a computer simulation for this simple mechanism implies that the reaction mechanism of the M. pulchella enzyme comprises the condensation and hydrolysis reactions, while the mechanism of the A. niger enzyme further includes the reaction producing xylotrisaccharide

Comparison of Xylan and Methyl β-Xyloside-Induced Xylanases from Streptomyces sp.

Three xylanases induced by xylan from Streptomyces sp. no. 3137 were purified to homogeneity. The enzymatic, physicochemical, and immunological properties of the enzymes were compared with those of three xylanases induced by non-metabolizable methyl β-xyloside. It was found that each xylanase produced under different culture conditions showed very similar properties