Topic
Melibiose
About: Melibiose is a research topic. Over the lifetime, 1002 publications have been published within this topic receiving 27300 citations. The topic is also known as: Melibiose.
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TL;DR: The crystal structure of α-melibiose monohydrate (C12H22O11·H2O) was determined by direct methods using two-dimensional cosine invariants as discussed by the authors.
Abstract: The crystal structure of α-melibiose monohydrate (C12H22O11·H2O) was determined by direct methods using two-dimensional cosine invariants. The space group is P212121, with Z=4 and unit cell dimensions of a=15.814(5), b=10.924(5), c=8.903(4) A. The structure was refined to R=0.044 for 1439 reflections measured with MoKα radiation. Difference synthesis indicated the partial (15%) random substitution of α-melibiose molecules by the β-anomer. The molecular conformation of α-melibiose is almost the same as that previously found in the melibiose moiety of raffinose, although some of the bond lengths and angles are significantly different. The molecules are linked by complex hydrogen-bond systems which consist of six-link finite chains and five-membered closed loops.
13 citations
TL;DR: The results support the view that the alterations in the melibiose carrier and in the Na+(Li+)/H+ antiporter, observed in the mutants, are not genetically linked.
Abstract: Revertants that showed normal cation recognition for melibiose transport were isolated from mutants with altered cation recognition (W3133-2S and W3133-2T) of Escherichia coli. Although the original two mutants possessed a second alteration, an increased activity of the Na+(Li+)/H+ antiporter, the revertants, which possessed the normal melibiose carrier, still showed altered properties of the Na+(Li+)/H+ antiporter. These results support the view that the alterations in the melibiose carrier and in the Na+(Li+)/H+ antiporter, observed in the mutants, are not genetically linked.
13 citations
TL;DR: The purified enzyme was active toward various substrates, including galactose, dihydroxyacetone, guar gum, lactose, melibiose, methyl‐galactopyranoside, and raffinose, but SDS was an inhibitor but EDTA, Tween 80, NH4+, Na+, Mg2+, K+, and glycerol were not.
Abstract: Extra-cellular production of a novel galactose oxidase from Fusarium acuminatum using submerged fermentation was studied. Glucose (1.0% w/v) was used as the sole carbon source. Maximum galactose oxidase production (approximately 4.0 U/ml) was obtained when fermentation was carried out at 25 degrees C, with orbital shaking (100 rpm) and an initial medium of pH 7.0, for 96 h, using a 2% (v/v) inoculum made from a homogenized four-day-old liquid culture, in the presence of copper, manganese, and magnesium. The enzyme was purified by one-step affinity chromatography, with a recovery of 42% of the initial activity. The purified enzyme ran as a single band of 66 kDa in SDS-PAGE. Optimal pH and temperature for the enzyme activity were 8.0 and 30 degrees C, respectively. The enzyme was thermoinactivated at temperatures above 60 degrees C. The purified enzyme was active toward various substrates, including galactose, dihydroxyacetone, guar gum, lactose, melibiose, methyl-galactopyranoside, and raffinose. SDS was an inhibitor but EDTA, Tween 80, NH(4)(+), Na(+), Mg(2+), K(+), and glycerol were not. The Michaelis-Menten constant (K(m)) for galactose was estimated to be 16.2 mM, while maximal velocity (V(max)) was 0.27 micromol of H(2)O(2) . ml(-1) . min(-1).
13 citations
TL;DR: The strain of E. coli in the title was found to produce considerably this enzyme adaptively, and showed optimum pH and temperature at 6.8 and 37°C, respectively, with the substrate p-nitrophenyl-α-D-galactoside (PNPG).
Abstract: Galactosylsucroses contained in soybeans are not digestible. Thus we wished to detect α-galactosidase (EC 3. 2. 1. 22) in intestinal bacteria. The strain of E. coli in the title was found to produce considerably this enzyme adaptively. We could prepare rather pure solution of the enzyme from the sonicate of the strain. It was purified about 142-fold. It showed optimum pH and temperature at 6.8 and 37°C, respectively, with the substrate p-nitrophenyl-α-D-galactoside (PNPG). Dilute enzyme solutions were very unstable even at 0_??_5°C. However, concentrated solutions were considerably stable. The Michaelis constant (M) was 1.07×10-4, 2.33×10-3, and 3.65×10-1 for PNPG, melibiose, and raffinose, respectively, The maximum velocity (mole/min/mg protein) was 2.72×10-5, 2.67×10-5, and 2.04×10-5, respectively for the same three substrates. This enzyme had a weak transferase action.
12 citations