Purification and properties of a membrane-bound aldehyde dehydrogenase from rat liver microsomes

A membrane-bound aldehyde dehydrogenase was solubilized from rat liver microsomes and purified about 150-fold by chromatography on ω-aminohexyl- and 5′-AMP-Sepharose columns with a recovery of about 40%. The purified enzyme was homogeneous upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis and its monomeric molecular weight was estimated to be 51,000. In aqueous solution, it existed as large, polymeric aggregates. Its activity towards straight-chain aliphatic aldehydes increased as their carbon chain length was increased at least up to dodecanal, whereas aldehyde dehydrogenase in the cytosolic fraction of rat liver was most active with hexanal as substrate.     

Human erythrocyte glutathione reductase. I. Purification and properties.

1. Glutathione reductase (NAD(P)H:oxidized-glutathione oxidoreductase, EC. 1.6.4.2) from human erythrocytes was purified 49 000-fold with an overall yield of 15% and a 280/460 nm absorbance ratio of 6.03. The procedure used was the method of Worthington and Rosemeyer modified by addition of heating and recrystallization. 2. It was concluded from the results of purification, electrofocusing and inhibition studies that glutathione reductase is a single enzyme which used both NADPH and NADH as hydrogen donors. 3. Apoenzyme cross-reacts with the antibody to the holoenzyme but has a slightly reduced affinity to the antibody. Apoenzyme can be removed from the hemolysate by heating and centrifugation without loss of holoenzyme. 4. Indirect immunological assay of the specific activity of the erythrocyte glutathione reductase is possible in the enzyme saturated with FAD.     

Maintenance and amplification of cell-associated immunological memory in in vivo culture system

By employing bovine serum albumin as antigen and the capsular polysaccharide of Klebsiella pneumoniae as adjuvant, maintenance and amplification of immunological memory were analyzed in an in vivo culture system in mice. For this purpose, the double cell transfer technique was employed to minimize the influence of regulatory factors on memory expression. Memory associated with primed cells is maintained at the original level during in vivo culture for at least a month in the absence of antigen. In contrast, memory is amplified more than 30 times during this period by stimulation with antigen. This secondary increase in memory does not require the action of adjuvant. Neither the residual primary antigen nor preformed primary antibody seems to play a significant role in the maintenance and amplification of memory of the primed cells. From these results it is probable that the enduring immunological memory in actively immunized mice is conveyed by long-lived memory cells, and additional antigenic stimulating on once-established memory cells serve to amplify (not simply to maintain) memory in a secondary fashion.     

The activation of coagulation factor X. Identity of cleavage sites in the alternative activation pathways and characterization of the COOH-terminal peptide.

Bovine Factor X can be activated by two alternative pathways. The first, favored at high concentrations of the complex of tissue factor and Factor VII, is initiated by the action of Factor VII on Factor X to cleave an activation peptide from the NH2 terminus of the heavy chain, to produce alpha-Xa. This is then converted autocatalytically to another form of Factor Xa, beta-Xa, by the loss of a 17-residue glycopeptide from the COOH terminus of the heavy chain, in a lipid-dependent reaction. The alternative pathway, favored at lower activator concentrations, is initiated by the action of Factor Xa on Factor X, in the presence of lipid, to release the same COOH-terminal peptide as is produced in the conversion of alpha-Xa to beta-Xa. The intermediate produced by the loss of this peptide from Factor X,I1, can be activated directly to beta-Xa by the tissue factor-Factor VII complex, with the loss of the same NH2-terminal peptide as is produced in the conversion of Factor X to alpha-Xa. The autocatalytic activation of Factor X by Factor Xa described previously occurs to a marked extent only at very low activator concentrations, and has been shown to proceed largely by the loss of the normal NH2-terminal peptide from the heavy chain of I1-Initial experiments show that neither peptide affects the rate of coagulation by either the extrinsic or intrinsic pathways. The amino acid sequences have been determined on both sides of the peptide cleavages, and it has been shown that the cleavage sites are the same, regardless of the pathway of activation. The amino acid sequence and carbohydrate composition of the COOH-terminal peptide have been determined. The carbohydrate moiety is attached via an O-glycosidic linkage at a threonine residue, and contains galactosamine but no glucosamine.     

Studies of pesticides effects on Chlorella metabolism II. Effect of DCMU on galactolipid metabolism

DCMU (N'-(3,4-dichlorophenyl)-N, N-dimethylurea) was testedfor effects on the metabolism of galactolipids in Chlorellaand chloroplasts isolated from higher plants. In Chlorella,DCMU affected galactolipid synthesis in the light more thanthat of other lipids, but it showed no effect on lipid synthesisin the dark. DCMU did not affect the turnover of galactolipidsin the light. In vitro studies using ¹⁴C-acetate or ¹⁴C-UDP-galactoseas a precursor showed that DCMU had no effect on the synthesisof gross lipid or galactolipids in chloroplasts isolated fromhigher plants. The significance of these observations are discussed. (Received September 21, 1974; )     

Studies on the Foaming Property of the Chicken Egg White

The egg white was treated under various whipping conditions, and its foaminess measured. At the same time, the amounts of the coagulated proteins formed from each egg white and their constituent hexose were measured. From these results, discussions were made about the relation between the foaminess of the egg white and the amount of the coagulated proteins under various whipping conditions.     

Changes in the Shape and Surface Hydrophobicity of Ovalbumin during Its Transformation to S-Ovalbumin

Intrinsic viscosity, Stokes radius and the hydrophobic coefficient of Keshavarz and Nakai [Biochim. Biophys. Acta, 576, 269 (1979)] were measured to compare the shape and surface hydrophobicity of ovalbumin and s-ovalbumin. Both the intrinsic viscosity and Stokes radius of s- ovalbumin were smaller than those of ovalbumin, which suggests that the configuration of s- ovalbumin became more compact during the ovalbumin-s-ovalbumin transformation. The hydrophobic coefficient of s-ovalbumin was larger than that of ovalbumin, which suggests that the surface hydrophobicity of s-ovalbumin was larger than that of ovalbumin. Further, these properties were measured for ovalbumin samples obtained at various stages of ovalbumin-s-ovalbumin transformation. Changes in the shape and surface hydrophobicity of ovalbumin were not found in the first stage of ovalbumin-s-ovalbumin transformation. They changed rapidly in the last stage of the ovalbumin-s-ovalbumin transformation.     

Lagrangian tracking measurements revealed the temporal dynamics of nitrogen and phosphorus spiralling in a large Japanese river

Limnology - The in-stream processing of nutrients plays an important role in the fluvial nutrient transport from lands to the ocean, but few empirical studies have addressed the temporal dynamics...     

A Geometry-Based Multiple Testing Correction for Contingency Tables by Truncated Normal Distribution

Statistics in Biosciences - Inference procedure is a critical step of experimental researches to draw scientific conclusions especially in multiple testing. The false positive rate increases unless...