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.

Nutritional studies of eastern spruce budworm (lepidoptera: tortricidae): i. soluble sugars

Abstract: An absolute requirement for sugar could not be shown but laboratory rearing experiments using artificial diets have demonstrated a definite increase in weight of adult spruce budworm (Choristoneura fumiferana (Clem.) Freeman) with increasing dietary levels of certain sugars. Males exhibit a threshold of 0.9% soluble sugars above which higher sugar levels produce no further increases in size. Females respond with an increase in size up to 4.0%, the highest level tested. Generally, faster development rates accompany greater mature weights on diets with higher nutrient levels.Maltose, raffinose, glucose, sorbitol, sucrose, and fructose are all good sugar sources. Galactose and trehalose are only slightly inferior. Lactose, ribose, melibiose, xylose, mannose, arabinose, and melezitose in the diet are little different from the sugarless control. Sorbose is somewhat inhibitory.Results of transfer experiments confirm the importance of sugar particularly during late larval development. They also indicate that a high protein diet during early instars has a significant effect on development rates. These results suggest that departure from the normal synchrony of development in the insect and its host can affect both rate of development and mature size of the insect.

Mechanisms of Carbohydrate Transport

Abstract: This chapter discusses the salient features of lactose and melibiose permeases. Early experiments established that the melibiose permease in Salmonella typhimurium can couple substrate uptake to Na+ uptake with a stoichiometry of 1:1, and that sugar-cation symport can account for energization of the system. Some evidence suggests that the lactose and melibiose permeases exhibit common structural and functional attributes, and are, therefore, evolutionarily related. Both permeases function by cation co-transport, probably by a similar carrier-mediated mechanism. While the lactose permease functions exclusively by sugar-H + co-transport, the melibiose permease couples sugar uptake to the symport of H + , Li + , or Na + , depending of the conditions, the bacterial strain, and the sugar substrate under study. The chapter also discusses the genetics and biochemistry of the maltose regulon, encoding the maltose catabolic enzyme system. It describes the topology of the proteins of the maltodextrin permease and catabolic enzyme system in Escherichia coli . Maltoporin preferentially binds and transports hexoses of the gluco configuration and oligosaccharides in which the glucosyl residues are linked α-1,4. However, these in vitro specificity data are insufficient to account for relative in vivo transport rates.

α-Galactosidase Activity of Lactobacilli

Abstract: α-Galactosidase (EC 3.2.1.22) activity was observed in cell-free extracts of Lactobacillus fermenti, L. brevis, L. buchneri, L. cellobiosis, and L. salivarius subsp. salivarius. The cultural conditions under which the enzyme activity was detected suggest that the enzyme is constitutive and present in the soluble fraction in the cell. The enzyme preparations readily hydrolyzed melibiose and other oligosaccharides containing α(1 → 6) linked galactose. Although the cell-free extracts of L. fermenti and L. brevis are negative for β-fructofuranosidase (EC 3.2.1.26), they hydrolyzed melibiose, stachyose, and raffinose in decreasing order of activity. The β-fructofuranosidase-positive L. buchneri, L. cellobiosis, and L. salivarius preparations hydrolyzed melibiose, raffinose, and stachyose in decreasing rates of activity. The α-galactosidases from different lactobacilli showed optimum activity in pH range 5.2 to 5.9. L. fermenti and L. salivarius preparations exhibited maximum activity between 40 to 44 C and 48 to 51 C, respectively, whereas a 38 to 42 C range was observed for other lactobacilli. Cell-free extract of L. cellobiosis was studied for transgalactosylase activity. When incubated with melibiose, a new compound was detected and tentatively identified as manninotriose.

NMR characterization of saccharides in Italian honeys of different floral sources.

Abstract: The saccharide profiles of 5 different botanical species in 86 Italian honey samples were investigated by 1H and 1H–13C NMR spectroscopy. Nineteen saccharides were identified in the aqueous extracts, namely, fructose, glucose, gentiobiose, isomaltose, kojibiose, maltose, maltulose, melibiose, nigerose, palatinose, sucrose, turanose, erlose, isomaltotriose, kestose, maltotriose, melezitose, raffinose, and maltotetraose. PCA performed on NMR spectral regions, in particular between 4.400 and 5.700 ppm and the fructose signal at 4.050 ppm, revealed a partial sample grouping. The score contribution plots derived from PCA performed using the mean values for the buckets of the anomeric region for each floral source allowed the identification of saccharides characterizing different honeys. OPLS-DA models were further evaluated to confirm the previous findings. OPLS-DA models were also built to highlight differences between polyfloral and high mountain polyfloral honeys and between high mountain polyfloral and rho...

Analysis of Melibiose Mutants Deficient in α-Galactosidase and Thiomethylgalactoside Permease II in Escherichia coli K-12

Abstract: Three types of mutants (mel−) unable to metabolize the α-d-galactoside, melibiose, were derived from Escherichia coli K-12. One type lacked α-galactosidase; another lacked a specific transport system, termed thiomethylgalactoside (TMG) permease II; and the third lacked both of these functions. The mutational sites were genetically mapped by recombination frequency with different markers and by determination of chromosomal transfer in interrupted-mating experiments. All three mel− mutant types mapped in a cluster near to the metA marker on the E. coli chromosome and were cotransducible. Induction studies revealed that the three α-d-galactosides, melibiose, melibiitol, and galactinol, induced α-galactosidase and TMG permease II coordinately; d-galactose also induced them but only in a galactokinaseless mutant. These data suggest that α-galactosidase and TMG permease II may be components of a common operon.