Ra. Paggi et al., EFFECT OF SALTS ON THE ACTIVITY OF NITRATE REDUCTASE FROM THE PHOTOSYNTHETIC BACTERIUM RHODOBACTER-SPHAEROIDES SW, Journal of basic microbiology, 35(1), 1995, pp. 47-52
The effect of different salts on the nitrate reductase (NR) activity o
f Rhodobacter sphaeroides SW was studied. An increase of the activity
in the presence of monovalent cations was observed (90, 80 and 77% wit
h Na+, K+ and NH4+, respectively), whereas divalent cations inhibited
the enzyme activity (30 acid 85% with Ca2+ and Mg2+). Both activation
or inhibition of the NR activity were reversible. These results could
be explained by the interaction of cations with negatively charged ami
no acids. On the other hand, several anions were also effective in sti
mulating NR activity (Cl- > NO3- > Br- > I- > SCN-), suggesting that t
he degree of hydration of the enzyme molecule might influence its acti
vity. Finally, the effect of salts on the NR activity of R. sphaeroide
s SW can heattributed to both electrostatic and hydrophobic interactio
ns.