Search

The F1 complex of the ATP synthase of Streptomyces lividans was isolated and purified. The procedure involved the solubilization of F1 from membranes with buffer of low ionic strength in the presence of EDTA, ion-exchange chromatography and gel filtration. The purified F1 complex from S. lividans (SLF1) consists of five subunits α, β, γ, δ and ε with molecular masses of 58000, 50000, 36000, 28000 and 13000, respectively and exhibits immunological cross-reactivity with the F1 portion purified from Escherichia coli (ECF1). The enzymatic properties of SLF1 were determined by the use of microtiter-plate-based assay and compared with data obtained for ECF1. ATPase activity of SLF1 (specific activity: 20–30 U/mg) was only observed in the presence of high concentrations of Ca2+ (to mM). Stimulation of the ATPase activity by Mg2+ was not detectable; quite to the contrary, Mg2+ inhibited the Ca2+-stimulated activity of SLF1. SLF1 was re-bound to F1-stripped membranes of S. lividans, but not to F1-stripped membrane vesicles of E. coli. In contrast, ECF1 could be cross-reconstituted with F1-stripped membranes of S. lividans; however, a structural but not a functional reconstitution of the hybrid F1Fo complex was observed. [ABSTRACT FROM AUTHOR]

Reports on the purification and characterization of brain pyridoxal kinase from sheep brain. Use of ammonium sulphate fractionation, diethylaminoethanol-cellulose chromatography, affinity chromatography and Sephadex G-100 gel filtration; Molecular mass of the native enzyme.

A protein, which facilitates assembly ora nucleosome-like structure in vitro, was previously partially purified from mouse FM3A cells [Ishimi, Y. et al. (1983) J. Biochem, (Tokyo) 94, 735-744]. The protein has been purified to approximately 80% from FM3A cells by using histone-Sepharose column chromatography. It sedimented at 4.6 S and had a molecular mass of 53kDa. A preincubation of core histones with the 53-kDa peptide before DNA addition was necessary for the nucleosome assembly. The 53-kDa peptide bound to core histones and formed a 12-S complex. This complex contained stoichiometrical amounts of the 53-kDa peptide and core histones, and the core histones in this complex were composed of equal amounts of H2A, H2B, H3 and H4 histones. The nucleosomes were assembled by adding pBR322 DNA to the 12-S complex. When mononucleosome DNA and core histones were mixed in the presence of the 53-kDa peptide, formation of a 10.5-S complex was observed. The complex contained DNA and core histones in equal amounts, while no 53-kDa peptide was detected in the complex. From above results it is suggested that the 53-kDa peptide facilitates nucleosome assembly by mediating formation of histone octamer and transferring it to DNA. Rat antibody against the 53-kDa peptide did not bind to nucleoplasmin from Xenopus eggs. The relationship between the 53-kDa peptide and nucleoplasmin is discussed. [ABSTRACT FROM AUTHOR]

The results reported in the present paper and N-terminal sequence homologies established by other authors strongly support the assumption that the gastric protease previously called bovine pepsin I or bovine pepsin B belongs to the aspartate protease group and corresponds to gastricsin (or pepsin C) (EC 3.4.23.3) from other species. Bovine gastricsin was prepared from commercial extracts of adult bovine veils by a procedure involving DEAE-cellulose chromatography, gel filtration on Sephacryl S-200 and a further DEAE-cellulose chromatography. The preparation thus obtained was shown to be free of chymosin and bovine pepsin A by immunodiffusion, selective inactivation in urea and isoelectric focusing. Us molecular weight was estimated by gel filtration to be 32800. Bovine gastricsin displayed microheterogeneity on isoelectric focusing with pi values of the components ranging from 3.5 to 4.0. Chromatography of bovine gastricsin on hydroxyapatite separated three fractions, none of them being homogeneous by isoelectric focusing. Concanavalin-A—Sepharose 4B bound bovine gastricsin to some extent, but without any significant fractionation. Proteolytic activity could be detected directly on the isoelectric focusing gel for all the components of gastricsin and its fractions from hydroxyapatite and concanavalin-A—Sepharose 4B. Bovine gastricsin and its fractions from hydroxyapatite have similar amino acid compositions, different from those of bovine chymosin and pepsin A but obviously related to those of human, simian and porcine gastricsins. Bovine gastricsin which is inactivated by reaction with diazoacetyl-DL-norleucine methyl ester and with 1,2-epoxy-(p-nitrophenoxy)propane in a 1:1 and 1:2 stoichiometry, respectively, is able to hydrolyse a synthetic hexapeptide, Leu-Ser-Phe(NO2)-Nle-Ala-Leu-OMe, used as reference substrate for aspartate proteases, and exhibits a low activity towards N-acetyl-L-phenylalanyl-L-diiodotyrosine. Its specific clotting activity with χ-casein as substrate is only half of that of chymosin and pepsin A. [ABSTRACT FROM AUTHOR]

Chromatography on DEAE-cellulose and gel filtration on Sephadex revealed that pyrazon dioxygenase from pyrazon-degrading bacteria consists of three different enzyme components. No component alone oxidizes the phenyl moiety of pyrazon, only when the three components are combined can oxidation be detected. Following electron paramagnetic resonance and ultraviolet measurements the protein nature of the three components was determined: component A1 (molecular weight about 180000, red-brown in colour) is an iron-sulphur protein. The existence of approximately two moles of iron and two moles of inorganic sulphur per mole of protein was demonstrated. This enzyme component was purified to homogeneity in disc elcctrophoresis. Component A2 is a yellow protein of a molecular weight of about 67000. FAD was shown to be the prosthetic group of this protein. Component B (molecular weight about 12000, brown in colour) is a protein of the ferredoxin type, which was purified to homogeneity, as demonstrated by disc electrophoresis. A hypothetical scheme for the cooperation of the three components is proposed: component A2 accepts as cosubstrate NADH and functions as a ferredoxin reductase. The ferredoxin, component B, has the function of an electron carrier. The conversion of the substrates is effected by component A1, the terminal dioxygenase. [ABSTRACT FROM AUTHOR]

Poly(ADP-ribose) polymerase with a high specific activity was obtained from Ehrlich ascites tumor cells by extraction of nuclei with 175 mM potassium phosphate, followed by chromatography on DNA-agarose. Electrophoretic analysis indicated that the preparation contained two proteins, one of which was shown to catalyze the synthesis of poly( ADP-ribose). As expected from results obtained by other workers, the synthesis was inhibited by nicotinamide and thymidine. and stimulated by DNA. Addition of histones gave inhibition of the synthesis, unless DNA was present in the reaction mixture. [ABSTRACT FROM AUTHOR]

32P-labelled N-formyl methionyl transfer RNA from Escherichia coli strain CA265 was purified by chromatography on a column DEAE Sephadex followed by chromatography on benzoylated DEAE cellulose. Nucleotides from ribonuclease T1 and pancreatic ribonuclease digests of tRNAF were separated and their sequences determined. tRNAF consists of 77 nucleotides of which pCG is 5′-terminal and CAACCOH is 3′-terminal. [ABSTRACT FROM AUTHOR]