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Biomedical subjects

H Sandermann

Publications and source records attributed to H Sandermann.

At least 91 records · Page 5Linked to original sources
PubMed1977

Isolation of alpha-glucan and lipopolysaccharide fractions from Acetobacter xylinum.

A cellular phenol-water extract of Acetobacter xylinum NRC 17007 was fractionated on Sepharose 4 B. The fraction eluting with the void volume consisted to about 95% of glycogen-like material. The lipopolysaccharide fraction was of lower molecular weight and had the following composition (%, w/w): Mannose, 42; glucose, 7; galactose, 3.8; heptose, 2; 2-keto-3-deoxy-octonate, 1.2; glucosamine, 3.3; phosphate, 4.5; total fatty acids, 3.9. Among the fatty acids, 3-hydroxy-tetradecanoic acid was present, and 2-hydroxy-hexadecanoic acid predominated.

Carbohydrates↗
PubMed1977

beta-D-Galactoside transport in Escherichia coli: substrate recognition.

1. A number of galactosides and other sugar compounds were examined as inhibitors of facilitated or active transport by the lactose permease system of Escherichia coli. Efficient inhibition required an alpha- or beta-anomeric galactopyranosyl ring of D-configuration, a free 6-hydroxyl group, and a certain aglycone size which was reached, for example, by monosaccharide or nitrophenyl substituents. 2. Aromatic alpha-D-galactopyranosides acted as high-affinity inhibitors (Ki, below 50 micrometer). At least two of them were not transported, in contrast to alpha-galactoside disaccharides and to aromatic beta-D-galactopyranosides. 3. beta-D-Galactoside transport was not significantly inhibited by specific inhibitors and transitionstate analogues of beta-galactosidase (D-galactal, D-galactonolascone). 4. The beta-D-galactopyranoside, lactitol, and alpha-D-galactopyranoside, galactinol, were not efficiently bound by the lactose permease system, although the maximal rate of uptake of lacitol was similar to that of lactose. By comparison with several structurally related D-galactopyranosides, the decreased affinity was attributed to an effect of the membrane/water interface. A model for substrate recognition by the lactose permease system is presented.

Biological Transport↗
PubMed1977

beta-D-Galactoside transport in Escherichia coli. Reversible inhibition by Aprotic Solvents and its Reconstitution in transport-negative membrane vesicles.

At relatively low concentrations (less than 3M) the aprotic solvents: dimethylsulfoxide, N-methylpyrrolidone, tetramethylurea and hexamethylphosphoric triamide, inhibited beta-D-galactoside transport by whole cells, and the derived membrane vesicles of Escherichia coli. Inhibition was not due to gross leakiness of the membrane and could be largely reversed by a simple washing procedure...

Binding, Competitive↗
PubMed1976

Solubility of phospholipid polar group model compounds in water.

The aqueous solubilities of the Na+ and Ca2+ salts and the free acid forms of phosphorylcholine, phosphorylethanolamine and D,L-phospho-serine, respectively, were found to be below the polar group concentrations calculated for bilayers of the corresponding phospholipids.

Biological Transport↗
PubMed1976

A possible correlation between lipid hydration and lipid activation of the C55-isoprenoid alcohol phosphokinase apoprotein.

1. A direct method for determining the binding of triated water to lipids is described. The experimental conditions were practically identical to those previously employed (1974) in the determination of the cofactor activities of a series of oleyl-lipids in reactivation of the C55-isoprenoid alcohol phosphokinase apoprotein. 2. Active cofactor lipids (dioleyl lecithin, sodium oleate, 1-monoolein, 1-monomyristin)bound between 2.3 and 5.3 nmol 3H2O per nmol lipid, whereas less than 0.14 nmol 3H2O were bound per nmol of the inactive lipids (1,2- and 1,3-diolein, triolein, oleyl alcohol, methyl oleate, cholesteryl oleate). 3. When exposed to 3H2O vapour, the active lipids adsorbed between 1 and 2 nmol 3H2O per nmol lipid, whereas the inactive lipids adsorbed less than 0.1 nmol 3H2O per nmol lipid. 4. The active lipid cofactor, egg lecithin, bound more than twice as much 3H2O as egg phosphatidylethanolamine which was devoid of cofactor activity in the absence of detergent. 5. Appropriately hydrated lipid polar groups are concluded to be required for an alignment with polar amino acid side chains of the enzyme apoprotein in the formation of a mixed micellar lipoprotein complex. The enzyme reaction might occur at the resulting lipoprotein/water interface.

Apoenzymes↗