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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, a general mechanism involving the formation of intermediate enodiol anion has been suggested and the effects of dielectric constant and salts have been studied in detail.
16 citations
TL;DR: The findings support the previous conclusion that Gly117 plays an important role in cation binding and translocation and block the lethal effect of elevated melibiose transport in the Gly117 mutants.
Abstract: The melibiose permease of Salmonella enterica serovar Typhimurium (MelBSt) catalyzes symport of melibiose with Na+, Li+, or H+. Bioinformatics and mutational analyses indicate that a conserved Gly117 (helix IV) is a component of the Na+-binding site. In this study, Gly117 was mutated to Ser, Asn, or Cys. All three mutations increase the maximum rate (Vmax) for melibiose transport in Escherichia coli DW2 and greatly decrease Na+ affinity, indicating that intracellular release of Na+ is facilitated. Rapid melibiose transport, particularly by the G117N mutant, triggers osmotic lysis in the lag phase of growth. The findings support the previous conclusion that Gly117 plays an important role in cation binding and translocation. Furthermore, a spontaneous second-site mutation (P148L between loop4-5 and helix V) in the G117C mutant prevents cell lysis. This mutation significantly decreases Vmax with little effect on cosubstrate binding in G117C, G117S, and G117N mutants. Thus, the P148L mutation specifically inhibits transport velocity and thereby blocks the lethal effect of elevated melibiose transport in the Gly117 mutants.
16 citations
TL;DR: In this paper, the authors describe experiments in which the cysteine substitution for a charged residue was chemically changed by sulfhydryl reagents (MTSEA and MTSET) or by iodoacetic acid or through oxidation by hydrogen peroxide so as to regain the original negative charge.
16 citations
TL;DR: The α-galactosidase activity was strongly inhibited by Ag+, Hg++, p -chloromercuribenzoate, galactose, and melibiose and the enzyme also seemed to catalyse a glycos...
Abstract: α-Galactosidase (EC 3.2.1.22) from Pycnoporus cinnabarinus was purified by precipitation with ammonium sulfate, column chromatographies on DEAE-Sephadex A-50, Sephadex G-100, CM-Sephadex C-50, and SP-Sephadex C-50, and isoelectric focusing. The purified enzyme was homogeneous on polyacrylamide disc gel electrophoresis, and the molecular weight was estimated to be about 210,000 by gel filtration on Sephacryl S-200 and about 52,000 by sodium dodecyl sulfate gel electrophoresis. The enzyme exhibited the optimum pH at 5.0 and was stable between pH 3 and 9. The optimum temperature of the enzyme was 75°C. The enzyme was thermostable at pH 5.0 and completely lost its activity after heating at 90°C or at pH 3.5. The Michaelis constants were 0.31 mM for p -nitrophenyl α-D-galactoside, 0.80 mM for melibiose, 2.16mM for raffinose, and 1.15 mM for stachyose. The α-galactosidase activity was strongly inhibited by Ag+, Hg++, p -chloromercuribenzoate, galactose, and melibiose. The enzyme also seemed to catalyse a glycos...
16 citations
TL;DR: A novel 57-kDa acidic α-galactosidase designated as HEG has been purified from the dry fruiting bodies of Hericium erinaceus and displayed remarkable resistance to acid proteases, neutral proteases and pepsin.
16 citations