Lactose residues

Akaike et al. [174-182] synthesized a new type of polystyrene derivative, poly(iV-p-vinylbenzyl-D-lactonamide) (PVLA), having lactose residues as side... 

The synthesis of neoglycoproteins has been performed by attachment of lactose residues to the initially carbohydrate-free enzyme. The reductive alkylation of the amino group of lysine residues is done using sodium cyanoborohydride (20). 

On the cellular level, functionality of the galactose and lactose residues was tested with primary rat hepatocytes. The MAD-Gal coated surface altered hepatocellular function. MTT (3- (4,5-dlmethylthlazol-2-yl)-2, 5-dlphenyltetrcizolium bromide) and Neutral Red (NR) uptake (Fig. 22) Increased for hepatocytes cultured on MAD-Gal coated polystyrene surfaces and the Increase correlated with the density of galactose molecules on the surface. MTT formation and NR uptake increased up to a concentration of 2.5 mmol/1 galactose and showed no saturation effect. CMF stands for crude membrane fraction which is taken as a reference. 

Saccharic acid. Use the filtrate A) from the above oxidation of lactose or, alternatively, employ the product obtained by evaporating 10 g. of glucose with 100 ml. of nitric acid, sp. gr. 1 15, until a syrupy residue remains and then dissolving in 30 ml. of water. Exactly neutralise at the boiling point with a concentrated solution of potassium carbonate, acidify with acetic acid, and concentrate again to a thick syrup. Upon the addition of 50 per cent, acetic acid, acid potassium saccharate sepa rates out. Filter at the pump and recrystaUise from a small quantity of hot water to remove the attendant oxahc acid. It is necessary to isolate the saccharic acid as the acid potassium salt since the acid is very soluble in water. The purity may be confirmed by conversion into the silver salt (Section 111,103) and determination of the silver content by ignition. 

Oxidation of galactose (or a galactose-containing sugar) to mucic acid. Dissolve 1 g. of galactose or lactose in a mixture of 10 ml. of water and 5 ml. of concentrated nitric acid contained in a small evaporating dish, and evaporate the solution to dryness on a water bath. Stir the cold residue with 10 ml. of cold water, filter off the mucic acid, wash it with cold water, dry and determine the m.p. (212-213° with decomposition). 

The lactose transporter (lac permease) of E. coli is without doubt the most intensively studied and best understood of the bacterial proton-linked sugar transporters. Since its sequence was reported in 1980 [233] prodigious efforts have been made to elucidate its molecular mechanism by site-directed mutagenesis and other means. These studies have recently been reviewed elsewhere [234,235] and so will not be discussed in detail here. The important question for the present Chapter is whether the protein is related to the sugar-transporter family and so has lessons to teach us about their mechanisms. The permease is a 417-residue protein, and, like the other... 

Diarrhea Drug related Antibiotic-induced bacterial overgrowth Hyperosmolar medications administered via feeding tubes Antacids containing magnesium Malabsorption Hypoalbuminemia/gut mucosal atrophy Pancreatic insufficiency Inadequate GIT surface area Rapid GIT transit Radiation enteritis Tube feeding related Rapid formula administration Formula hyperosmolalty Low residue (fiber) content Lactose intolerance Bacterial contamination... 

Ovchinnikov 234 237) has shown that bovine rhodopsin, although quite different in amino acid sequence (348 residues), also forms seven transmembrane helices. This structural similarity between bacterial and mammalian light activated membrane proteins is remarkable. Since the two amino acid sequences have little in common it would appear that the necessary requirement is seven transmembrane helices to form a channel which is specific for proton migration. For example it has been suggested that a similar arrangement and function is performed by the lactose permease of E. coli237). 

Harrison, Tarr and Hibbert96 investigated the production of levan from sucrose by the action of Bacillus subtilis Cohn and B. mesentericus Trevisan. Nutrient solutions containing 10% carbohydrate, 0.1% peptone, 0.2% disodium hydrogen phosphate and 0.5% potassium chloride were incubated at 37° for six days. Levan formation occurred only with sucrose and raffinose, and not with melezitose, lactose, maltose, D-xylose, D-glucose or D-fructose. It was therefore suggested that only those carbohydrates with a terminal D-fructofuranose residue were satisfactory substrates for levan formation. 

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