Partial purification and properties of acyl-CoA reductase from Clostridium butyricum.

A long chain acyl-CoA reductase of Clostridium butyricum has been partially purified from the 100,000g supernatant fraction of cell extracts. The enzyme reduces acyl-CoA derivatives to aldehydes in the presence of NADH. It is stable in dithiothreitol-containing buffers at 4 °C, heat-labile, and sensitive to sulfhydryl reagents. It is active with palmitoyl-CoA, stearoyl-CoA, oleoyl-CoA, and myristoyl-CoA. Its apparent molecular weight on Sephadex G-100 column chromatography is 50,000. In crude extracts and at low purification, an NADPH-dependent reduction of palmitaldehyde to cetyl alcohol was also observed. An acyl-CoA hydrolase was also observed in crude extracts.     

Postinductive actinomycin D effects on the concentrations of cadmium thionein, zinc thionein, and copper chelatin in rat liver

The time courses of induction in rat liver of copper chelatin by copper, cadmium thionein by cadmium, and zinc thionein by copper, cadmium, and zinc were monitorg metal were used in order to avoid toxic effects, being 5 mg zinc, 0.5 mg copper, and 0.25 mg cadmium per kg body weight. Peak times of induction and half times of decay observed were: copper chelatin (9 h, 8.6 h), cadmium thionein (18 h, 6.80 days), and zinc thionein (zinc rats, 18 h, 10.1 h; copper rats, 9 h, 18.2 h; cadmium rats, 24 h, 4.53 days). Administration of actinomycin D (1 mg per kg body weight) at the peak times of induction of the various proteins had no effect on the concentrations of chelatin or cadmium thionein observed up to 24 hours later, but in the case of zinc thionein, induced by zinc, copper, or cadmium, elevated concentrations were observed up to 23 h after administration of the drug. Such behavior is reminiscent of superinduction previously seen with other proteins and enzymes. We postulate that the intracellular concentration of free zinc in liver is of fundamental importance in the induction of zinc thionein, and this can be distributed by exogenous copper or cadmium resulting in the induction of synthesis of zinc thionein.     

The wavelength dependence of the turbidity of solutions of macromolecules

The experimental parameter describing the wavelength dependence of the turbidity of solutions of macromolecules is usually the negative slope of the graph of the logarithm of optical density vs the logarithm of the in vacuo wavelength, λ₀. Such slopes are the apparent exponents of 1/λ₀ in the turbidity equation. Their values depend upon the way the destructive interference of the scattered light, the refractive index increment, and the solvent refractive index change with wavelength. In this study, expressions for the wavelength exponents for isotropic rods, spheres, and random coils have been obtained and evaluated by representing the intraparticle interference functions, Q(λ₀), with series in even powers of 1/λ₀ and the refractive properties with Cauchy relations. Comparisons of calculated and observed exponents at wavelengths in the visible spectral region for aqueous solutions of four viruses have been made: for R17, T7, and PM2 bacteriophage, the exponents are greater than four; whereas for tobacco mosaic virus, they are less than four. The application of the turbidity relations to determine the size and molecular weight of biological macromolecules is discussed.     

Localization of angiotensin converting enzyme (kininase II). I. Preparation of antibody-hemeoctapeptide conjugates.

Antibodies to pig lung angiotensin converting enzyme (kininase II) were conjugated to a heme-octapeptide (8-microperoxidase, 8-MP) derived from cytochrome c. 8-MP, which has only one reactive amine, was coupled to antibody in a two-step procedure using a bifunctional active ester, bis-succinyl succinate. In the first-step, 8-MP-succinyl succinate, a stable compound which can be stored. In a second step, the remaining active ester was used for coupling to reactive amines of the antibody. The conjugate consists of 1.6-2.3 8-MP moieties per antibody. Using these procedures, the formation of complex polymers is avoided. Each molecule of conjugate possesses both immunoreactivity and peroxidatic activity. The conjugate has been used to localize angiotensin converting enzyme along the plasma membrane and associated caveolae of pig aortic endothelial cells in culture.     

Explanations for weight loss after ileojejunal bypass in gross obesity.

Twenty grossly obese patients underwent ileojejunal bypass operations. Measurements of calories lost in faeces showed that the malabsorption could not account for the weight loss. Furthermore, the malabsorption was not decreased two years after bypass, when weight was no longer being lost. Dietary restriction is therefore largely responsible for the weight loss and increased food intake for weight maintenance.     

Fungal fimbriae. I. Structure, origin, and synthesis.

Fine hair-like appendages on the cell walls of the another smut Ustilago violacea are described. These hairs are termed fimbriae because of their close similarity to the fimbriae (pili) found on certain Gram-negative bacteria. Cells of U. violacea may carry more than 200 fimbriae varying in length from about 0.5 mum to over 10 mum, and having a diameter of about 60-70 A. Some fimbriae produce knobs similar to those found on bacterial sex fimbriae. Log-phase cells are the most densely fimbriated, while stationary phase cells are devoid of fimbriae. The cells can be defimbriated by sonication, high-speed agitation, or centrifugation through a 40% sucrose solution. The fimbriae can regenerate in these defimbriated cells in about 1 h. This regeneration is inhibited by both cycloheximide and rifampin, but not by chloramphenicol and therefore appears to depend on de novo protein synthesis on cytoplasmic ribosomes. Similar long fimbriae are found on U. maydis and Leucosporidium (Candida) scottii. Short fimbriae, about 0.5 mum long, were found on all the other species of yeast-like fungi examined (Rhodotorula, Saccharomyces, Schizosaccharomyces, Hansenula, Lipomyces, Nadsonia, and Torulopsis spp.).     

Specificity of Ustilago maydis Killer Proteins

Bacteria and fungi were tested for sensitivity to Ustilago maydis killer strains carrying virus-like particles. Various species taxonomically related to U. maydis were sensitive.     

Sequence determination of peptides by mass spectrometry: methods for combining "wet" separation techniques with mass spectrometry.

Methods are described that allow the combination of established techniques for peptide separation, paper chromatography and electrophoresis, with mass spectrometry. The development of these methods is part of an ongoing effort in the search for a methodology for the systematic utilization of mass spectrometry for the elucidation of primary structure of proteins and peptides. Peptides and amino acids are detected on chromatograms by conversion to covalent derivatives that are also suitable for mass spectrometry. The most useful reagents for detection and derization of peptides reported here are dansyl chloride, N,N-dimethylaminobenzaldehyde, N,N-dimethylaminocinnamaldehyde, and N-hydroxysuccinimido β-naphthoate. Detection limits and mass spectra for some of these derivatives are reported.