Structural basis of eukaryotic nitrate reduction: crystal structures of the nitrate reductase active site.

Nitrate assimilation in autotrophs provides most of the reduced nitrogen on earth. In eukaryotes, reduction of nitrate to nitrite is catalyzed by the molybdenum-containing NAD(P)H:nitrate reductase (NR; EC 1.7.

Mechanistic and molecular investigations on stabilization of horseradish peroxidase C.

The enzyme horseradish peroxidase (HRP) shows a decreasing activity when the enzyme's substrate hydrogen peroxide is present with the degree of inactivation being dependent on the incubation time and the hydrogen peroxide concentration. Incubation times of some minutes do not inactivate the enzyme independent of the H2O2 concentration. After several hours, only 50% of the activity is found for a medium H2O2 excess, and a >100-fold excess of H2O2 completely inactivates the enzyme.