Metal Ions Hg Research Articles

Neuraminidase fromPasteurella haemolytica

A soluble extracellular antigen produced byPasteurella haemolytica serotype 1 possesses neuraminidase activity. The metal ions Mn2+, Mg2+, and Ca2+ stimulate enzyme activity, while the heavy metal ions Hg2+ and Fe3+ inhibit neuraminidase activity. Extensive dialysis of the enzyme with 50 mM ethylenediaminetetraacetic acid does not result in loss of enzyme activity. Antiserum prepared againstPasteurella haemolytica serotype 1 inhibits neuraminidase activity 2.0- to 2.7-fold, suggesting that neuraminidase is part of the antigenic complex. Initial rate kinetics of neuraminidase reveals that the Michaelis constant for fetuin is 3.84 mg/ml (96 μM) and the maximal velocity (Vmax) is 0.53 mmol/min/mg of protein.

Adsorption of metal cations on wool carbonising waste. Part 1. Adsorption isotherms

AbstractThe adsorption of various metal ions (Hg2+, Ag+, Ni2+, Cr3+, Al3+, Zn2+ and Pb2+) on wool carbonising waste has been investigated to assess its possible use as an adsorbent in water pollution control. Isotherms show that few metal ions (Hg2+, Ag+ and Ni2+) are adsorbed satisfactorily by this material. Moreover, the adsorption capacity of the plant material within the carbonising waste is higher than that of the keratin fraction. Equations fitting the experimental data can be used for the design of processing units.

Mercury and cadmium resistances mediated by the penicillinase plasmid in Staphylococcus aureus.

Resistance of Staphylococcus aureus mediated by the penicillinase (Pc-ase) plasmid to divalent metal ions of Hg and Cd was found to be controlled by different mechanisms. The Hg resistance of the Pc-ase plasmid-carrying organisms is based upon a process of changing the ion incorporated in the cell into a somewhat innocuous form. This process is independent of temperature and seems to be controlled by an inducible enzyme. The killing effect of Hg salts was not influenced by the coexistence of other di- or monovalent ions such as MgCl(2), CaCl(2), MnCl(2), and NaCl. No vaporization of Hg, which explains the resistance mechanism such as that proposed by Komura et al. for R factor-mediated Hg resistance in enterobacilli, was found in the case of Hg resistance in staphylococci. On the other hand, the resistance to Cd ion is mediated by some protective mechanism to retain the ion outside the cell. Pc-sensitive organisms not carrying the Pc-ase plasmid incorporate Cd ions into the cells, whereas the Pc-ase plasmid-carrying organisms do not. The incorporation of this ion is temperature dependent and does not take place at 4 C. When incubated with this ion at 4 C, Pc-sensitive organisms as well as Pc-resistant organisms are also able to show a resistance. The addition of CaCl(2) could eliminate the killing effect of CdCl(2) with a dose-effective response.

Effects of Divalent Metal lons upon Emissions of AgBr and AgBrl Grains at Liquid Nitrogen Temperature

Effects of divalent metal ions (Hg2+, Cu2+, Pb2+, Ni2+, Co2+, Cd2+, Fe2+, Zn2+, Ba2+, Sr2+ and Mn2+) have been examined upon various types of emissions from AgBr and AgBrI grains in photographic emulsions at liquid N2 temperature. Only Hg2+ and Cu2+ whose redox potentials are the most positive and the second most positive decreased the phetographic speeds, the intensitles of the delayed parts of the emissions at 600nm m the AgBr and AgBrI grains and at 540 nm from the AgBrI grains. Only Hg2+ decreased the intensity of the total emission at 600 nm from the AgBr grain. These results have led to the view that Hg2+ and Cu2+ provide electron traps to the grains.