RESEARCHERS AT YEREVAN STATE UNIVERSITY, DEPARTMENT OF BIOPHYSICS HAVE PUBLISHED NEW DATA ON BIOPHYSICS

Biotech Business Week
May 3, 2010

Researchers detail in ‘The effects of copper (II) ions on
Enterococcus hirae cell growth and the proton-translocating FoF1
ATPase activity,’ new data in biophysics. "Enterococcus hirae grow
well under anaerobic conditions at alkaline pH (pH 8.0) producing
acids by glucose fermentation. Bacterial growth was shown to be
accompanied by decrease of redox potential from positive values
(approximately +35 mV) to negative ones (approximately -220 mV),"
researchers in Yerevan, Armenia report (see also Biophysics).

"An oxidizer copper (II) ions (Cu(2+)) affected bacterial growth in a
concentration-dependent manner (within the range of 0.05 mM to 1 mM)
increasing lag phase duration and decreasing specific growth rate.

These effects were observed with the wild-type strain ATCC9790 and
the atpD mutant strain MS116 (with absent beta subunit of F(1) of the
F(o)F(1) ATPase) both. Also ATPase activity and proton-potassium ions
exchange were assessed with and without N,N’-dicyclohexylcarbodiimide
(DCCD), inhibitor of the F(o)F(1) ATPase. In both cases (DCCD ±), even
low Cu(2+) concentrations had noticeable effect on ATPase activity,
but with less visible concentration-dependent manner. Changes in the
number of accessible SH-groups were observed with E. hirae ATCC9790
and MS116 membrane vesicles. In both strains Cu(2+) markedly decreased
the number of SH-groups in the presence of K(+) ions. The addition
of ATP increased the amount of accessible SH-groups in ATCC9790 and
decreased this number in MS116; Cu(2+) blocked ATP-installed increase
in SH-groups number in ATCC9790. H(+)-K(+)-exchange of bacteria was
markedly inhibited by Cu(2+), but stronger effects were detected
together with DCCD. Moreover, discrimination between Cu(2+) and other
bivalent cation–Ni(2+) was shown," wrote Z. Vardanyan and colleagues,
Yerevan State University, Department of Biophysics.

The researchers concluded: "It is suggested that Cu(2+) ions inhibit
E. hirae cell growth by direct affect on the F(o)F(1) ATPase leading
to conformational changes in this protein complex and decrease in
its activity."

Vardanyan and colleagues published their study in Cell Biochemistry
and Biophysics (The effects of copper (II) ions on Enterococcus hirae
cell growth and the proton-translocating FoF1 ATPase activity. Cell
Biochemistry and Biophysics, 2010;57(1):19-26).

For additional information, contact Z. Vardanyan, Yerevan State
University, Dept. of Biophysics of the Biological Faculty, 1 A
Manoukian Str, 0025, Yerevan, Armenia.

Publisher contact information for the journal Cell Biochemistry and
Biophysics is: Springer, 233 Spring Street, New York, NY 10013, USA.