902-54-5Relevant articles and documents
Characterization of properties and transglycosylation abilities of recombinant α-galactosidase from cold-adapted marine bacterium pseudoalteromonas KMM 701 and its C494N and D451A mutants
Bakunina, Irina,Slepchenko, Lubov,Anastyuk, Stanislav,Isakov, Vladimir,Likhatskaya, Galina,Kim, Natalya,Tekutyeva, Liudmila,Son, Oksana,Balabanova, Larissa
, (2018/10/20)
A novel wild-type recombinant cold-active α-D-galactosidase (α-PsGal) from the cold-adapted marine bacterium Pseudoalteromonas sp. KMM 701, and its mutants D451A and C494N, were studied in terms of their structural, physicochemical, and catalytic properties. Homology models of the three-dimensional α-PsGal structure, its active center, and complexes with D-galactose were constructed for identification of functionally important amino acid residues in the active site of the enzyme, using the crystal structure of the α-galactosidase from Lactobacillus acidophilus as a template. The circular dichroism spectra of the wild α-PsGal and mutant C494N were approximately identical. The C494N mutation decreased the efficiency of retaining the affinity of the enzyme to standard p-nitrophenyl-α-galactopiranoside (pNP-α-Gal). Thin-layer chromatography, matrix-assisted laser desorption/ionization mass spectrometry, and nuclear magnetic resonance spectroscopy methods were used to identify transglycosylation products in reaction mixtures. α-PsGal possessed a narrow acceptor specificity. Fructose, xylose, fucose, and glucose were inactive as acceptors in the transglycosylation reaction. α-PsGal synthesized -α(1→6)- and -α(1→4)-linked galactobiosides from melibiose as well as -α(1→6)- and -α(1→3)-linked p-nitrophenyl-digalactosides (Gal2-pNP) from pNP-α-Gal. The D451A mutation in the active center completely inactivated the enzyme. However, the substitution of C494N discontinued the Gal-α(1→3)-Gal-pNP synthesis and increased the Gal-α(1→4)-Gal yield compared to Gal-α(1→6)-Gal-pNP.
Production of keto-disaccharides from aldo-disaccharides in subcritical aqueous ethanol
Gao, Da-Ming,Kobayashi, Takashi,Adachi, Shuji
, p. 998 - 1005 (2016/05/09)
Isomerization of disaccharides (maltose, isomaltose, cellobiose, lactose, melibiose, palatinose, sucrose, and trehalose) was investigated in subcritical aqueous ethanol. A marked increase in the isomerization of aldo-disaccharides to keto-disaccharides was noted and their hydrolytic reactions were suppressed with increasing ethanol concentration. Under any study condition, the maximum yield of keto-disaccharides produced from aldo-disaccharides linked by β-glycosidic bond was higher than that produced from aldo-disaccharides linked by α-glycosidic bond. Palatinose, a keto-disaccharide, mainly underwent decomposition rather than isomerization in subcritical water and subcritical aqueous ethanol. No isomerization was noted for the non-reducing disaccharides trehalose and sucrose. The rate constant of maltose to maltulose isomerization almost doubled by changing solvent from sub-critical water to 80 wt% aqueous ethanol at 220°C. Increased maltose monohydrate concentration in feed decreased the conversion of maltose and the maximum yield of maltulose, but increased the productivity of maltulose. The maximum productivity of maltulose was ca. 41 g/(h kg-solution).
Mode of action of a β-(1→6)-glucanase from Penicillium multicolor
Hattori, Takeshi,Kato, Yasuna,Uno, Shuji,Usui, Taichi
, p. 6 - 16 (2013/02/25)
β-(1→6)-Glucanase from the culture filtrate of Penicillium multicolor LAM7153 was purified by ammonium sulfate precipitation, followed by cation-exchange and affinity chromatography using gentiotetraose (Gen 4) as ligand. The hydrolytic mode of action of the purified protein on β-(1→6)-glucan (pustulan) was elucidated in real time during the reaction by HPAEC-PAD analysis. Gentiooligosaccharides (DP 2-9, Gen 2-9), methyl β-gentiooligosides (DP 2-6, Gen2-6 β-OMe), and p-nitrophenyl β-gentiooligosides (DP 2-6, Gen 2-6 β-pNP) were used as substrates to provide analytical insight into how the cleavage of pustulan (DP? 320) is actually achieved by the enzyme. The enzyme was shown to completely hydrolyze pustulan in three steps as follows. In the initial stage, the enzyme quickly cleaved the glucan with a pattern resembling an endo-hydrolase to produce a short-chain glucan (DP? 45) as an intermediate. In the midterm stage, the resulting short-chain glucan was further cleaved into two fractions corresponding to DP 15-7 and DP 2-4 with great regularity. In the final stage, the lower oligomers corresponding to DP 3 and DP 4 were very slowly hydrolyzed into glucose and gentiobiose (Gen 2). As a result, the hydrolytic cooperation of both an endo-type and saccharifying-type reaction by a single enzyme, which plays a bifunctional role, led to complete hydrolysis of the glucan. Thus, β-(1→6)-glucanase varies its mode of action depending on the chain length derived from the glucan.
