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Biomedical subjects

M M Werber

Publications and source records attributed to M M Werber.

At least 55 records · Page 3Linked to original sources
PubMed1978

Metal binding to myosin and to myosin DTNB-light chain.

The effects of various divalent cations, Ca2+, Mg2+ and Mn2+ on the intrinsic fluorescence of heavy meromyosin (HMM) and myosin 5,5'-dithio-bis-(2-nitrobenzoate) DTNB-light chain of rabbit striated muscle, are compared. At pH 6.4, th fluorescence change induced by the metal ions is present only in the isolated light chain and disappears in HMM, thus indicating an interaction between the heavy and light chains with respect to the binding of the metal ions. Whereas Mg2+ binds more strongly than Ca2+ to myosin, this order is reversed in the case of the DTNB-light chain.

Animals↗
PubMed1978

Structural and exchange properties of "Co(III)-phenanthroline-ATP": a labeling reagent for the active site of ATPases.

This paper reports on 1H and 31P NMR as well as EPR measurements of the labeling reagent of ATPase sites, "Co(III)-(phen)-ATP." This complex is found to be paramagnetic, as deduced both from its EPR spectrum and from the significant broadening, though almost unshifted, proton and phosphorus resonances. This paramagnetism is a result of the incorporation of the superoxide free-radical anion in the coordination sphere of the trivalent cobalt ion. Evidence for the presence of superoxide in the complex is based on competition experiments with cyanide, which is able to displace the superoxide anion. The latter was identified by its inducing effect on the photoreactivity of luminol. The displacement of superoxide by cyanide was accompanied by the abolition of the paramagnetism of the complex. The relative distances between the protons and phosphorus atoms of ATP and the superoxide anion in the complex were calculated using the NMR line-broadening data. Structural models compatible with the experimental results are proposed. Under conditions of excess of adenine nucleotides or phenanthroline, the coordinated ATP molecule becomes exchangeable. This phenomenon is attributed to the labilization of the cobaltic ion ligands induced by the superoxide anion.

Adenosine Triphosphatases↗
PubMed1976

Hydrophobic chromatography and fractionation of enzymes from extremely halophilic bacteria using decreasing concentration gradients of ammonium sulfate.

Ammonium sulfate fractionation of proteins from extremely halophilic bacteria on Sepharose 4B, carboxymethylcellulose, diethylaminoethylcellulose, and hexamethylenediamine-Agarose is described. Halophilic proteins are absorbed on these gels at 2.5 M ammonium sulfate and eluted by decreasing concentration gradients of this salt. The method has enabled the separation of malate dehydrogenase from glutamate dehydrogenase and aspartate aminotransferase on Sepharose 4B and the additional 15-fold purification of glutamate dehydrogenase on DEAE-cellulose. The technique is simple and convenient, operates at low cost, and possesses great power of resolution. The mechanism of adsorption is discussed and compared to previous instances of "hydrophobic chromatography". It is concluded that the retention of halophilic proteins on the polysaccharide gels at 2.5 M ammonium sulfate is due to hydrophobic interactions.

Ammonium Sulfate↗