Ready separation of proteins from nucleoprotein complexes by reversible modification of lysine residues.

Modification of proteins with citraconic anhydride altered the electrostatic relationship between cationic epsilon-NH3+ groups of lysine residues of proteins and anionic phosphate groups of nucleic acids, thereby destabilizing the nucleoprotein complex. This procedure facilitated the separation of proteins from nucleic acids at pH4-4.2.

Stabilization of proteins by solvents. Effect of pH and anions on the positive cooperativity of 2-nonanone binding to bovine serum albumin.

The binding of 2-nonanone to bovine serum albumin exhibited positive cooperativity at low molal ratios of binding, indicating stabilization of the hydrophobic binding sites at low concentrations of 2-nonanone. The degree of cooperativity was affected by the type of anion present as evidenced from the changes in the Hill coefficient. The effectiveness of anions in increasing the Hill coefficient followed the Hofmeister series for anions, i.

Prostaglandin E1 and E2 in bovine semen: quantification by gas chromatography.

Prostaglandins PGE1 and PGE2 extracted from bovine semen, purified via silicic column chromatography were quantified by gas chromatography as their methoxime methyl ester trimethylsilyl ether derivatives. The PGE2 and PGE2 concentrations of 19 bovine semen samples ranged from 395 +/- 225 and 487 +/- 407 ng/ml, respectively. A constant 1:1 ratio between PGE1 and PGE2 was observed.

A rapid method for the isolation of ribonuclease from yeast (Saccharomyces carlsbergensis).

A ribonuclease (RNAase; EC 3.1.14.

Microsomal phosphatidic acid phosphohydrolase of rat mammary tissue: I. General properties.

The microsomal bound phosphatidic acid phosphohydrolase from lactating rat mammary tissue had a specific activity of six nmoles per mg protein per minute. The optimum pH was 7.0; magnesium at 1.

Prostaglandins and their precursors in tissues from rats fed on trans, trans-linoleate.

Feeding trans,trans-9,12-linoleate to rats as 50 and 100% of the dietary fat decreased the concentrations of n-6 fatty acids, i.e. 18:2, 20:3 and 20:4, in heart, kidney, lung, adipose tissue and platelets of rats.

Kidney lipids: changes caused by dietary 9-trans, 12-trans-octadecadienoate.

Trans,trans-linoleate at 50 and 100% of dietary fat decreased kidney size and altered its composition. Trans,trans-linoleate as the sole source of dietary fat impaired growth and caused more severe symptoms of essential fatty acid deficiency than was observed with hydrogenated coconut oil (HCO). The concentration of renal cholesterol, phospholipids (PL), triglycerides (TG) and cholesteryl esters (CE) were also decreased.

Co-ordinate regulation of ethanolamine kinase and phosphoethanolamine cytidylyltransferase in the biosynthesis of phosphatidylethanolamine in rat liver.

Essential-fatty acid deficiency produces a 52% increase in the rate of phosphatidyl-ethanolamine synthesis in rat liver as calculated from results obtained in vivo [Trewhella & Collins (1973) Biochem. Biophys. Acta 296, 34--50].

Transport of organic ions in renal cortical luminal and antiluminal membrane vesicles.

Based upon saturability, kinetic analysis and specific inhibition, specific transport for the organic anion, p-aminohippurate was found in isolated luminal and antiluminal membrane vesicles from dog kidney cortex. The transport for organic anions in the two membranes differed from one another on the basis of kinetic parameters ((Km, Vmax and Ki for probenecid) and counterflow phenomenon (only the antiluminal membrane displayed the capacity to accelerate the exchange of p-aminohippurate). Also described is specific transport for the organic cation N1 methylnicotinamide in each membrane.

Isolation of luminal and antiluminal membranes from dog kidney cortex.

Luminal (brush border) and antiluminal (basal-lateral) membranes were isolated from canine renal cortex. The enzyme marker for luminal membrane, alkaline phosphatase was enhanced 19-fold and the antiluminal enzyme marker, (Na+ + K+)-ATPase, was enhanced 22-fold in their respective membrane preparation, while the amount of cross contamination was minimal. Contamination of these preparations by enzyme markers for lysosomes, endoplasmic reticulum and mitochondria was also low.

The effects of trans trans methyl linoleate on the concentration of prostaglandins and their precursors in rat.

Four groups of weanling male rats were fed a diet containing hydrogenated coconut oil (Treatment A); 9-trans, 12-trans linoleate (trans linoleate, (Treatment B); an equal mixture of 9-cis, 12-cis linoleate (cis linoleate) and trans linoleate (Treatment C); and cis linoleate (Treatment D); respectively for 12 weeks. The level of dietary fat was 11% of calories. Only trace amount of eicosatrienoic acid (C20:3w6) was detected in tissues, (liver, platelets) of rats in Treatments A and B.

Control of phosphatidylcholine synthesis and the regulatory role of choline kinase in rat liver. Evidence from essential-fatty acid-deficient rats.

Choline kinase and phosphocholine cytidylytransferase catalyse the rate-limiting steps of the cytidine pathway for the synthesis of phosphatidylcholine [Infante (1977) Biochem. J. 167, 847--849].

A novel method for determining equilibrium constants. CTP:phosphorylcholine cytidyltransferase.

A novel method for the determination of equilibrium constants for reversible reactions is described. The method is based on the measurement of initial velocities of isotope transfer for a given substrate-product pair of both the forward and reverse reactions as a function of the mass action of reactants. The reciprocal values of these initial velocities are plotted against the mass action ratios of reactants.

Effect of thiol reagents on extractability of protein from yeast.

The effect of soluble thiol reagents on the extractability of protein from yeast cells was studied. The incubation of yeast cells with dithiothreitol, 2-mercaptoethanol, or monothioglycerol markedly stimulated the release of soluble carbohydrates into the medium. There was a concomitant improvement (over twofold) in the extractability of protein from the yeast cells.