LaMotte Nitrate-Nitrogen Low Range Enzyme Kit - Manual (Page 7)

only pollution tolerant species will remain. If sediment from erosion and
run-off is trapped in the sunken roots and rotting vegetation the entire
waterway may fill in completely in a process called eutrophication.
In fast moving streams, nutrient levels may be high but the flow of water will
prevent the establishment of floating aquatic plants and algae. During
seasonal fluctuations the water flow may become reduced and streams will
then become choked with algae.
Industrial processes that use natural water for cooling, like power plants, can
be damaged when the source water is thick with algae. Bathers and boaters
using recreational waters will experience clumps of floating algae in the water
and rotting algae on the shoreline after an algae bloom.
Drinking water containing high nitrate levels can affect the ability of blood
to carry oxygen. This condition, called methemoglobinemia, is especially
harmful to infants and anyone with a compromised immune system.
Test ing for Ni trate
Widely used test methods utilize heavy metals to reduce the nitrate to nitrite.
The most commonly used metals are cadmium and zinc. Cadmium, which is
more hazardous than zinc, gives better sensitivity at low concentrations so it
is used in kits with lower ranges. Recently, a reagent system was developed
that has the sensitivity of cadmium reduction at low concentrations and uses
non-hazardous nitrate enzyme reductase to reduce nitrate to nitrite,
eliminating heavy metals.
En zyme Tech nol ogy
1
The Enzyme Vials contain both freeze-dried NADH (nicotinamide adenine
dinucleotide) and YNaR1 (yeast nitrate reductase version 1). The YNaR1 is
a recombinant form of NAD(P)H: Nitrate Reductase (Enzyme Commission
#EC 1.7.1.2). Nitrate Reductase (NaR) is present in all plants and many
types of yeast. It is the enzyme that starts the process of incorporating
nitrogen species into amino acids and proteins in these organisms. The
NaR1 formerly used was extracted from corn leaf. The current YNaR1 is
produced in the Pichia pastoris protein expression system; Pichia is a yeast,
similar to baker’s yeast. YNaR1 is more stable than the native plant enzyme
forms and can be produced cost-effectively by fermentation. A “handle” has
been engineered into the protein to enable purification by affinity
chromatography. Recombinant production eliminates lot-to-lot variation in
protein quality. The YNaR1 enzyme is comprised of two subunits of over 900
amino acids and 3 cofactors each – flavin adenine dinucleotide (FAD or
vitamin B-2), heme iron, and a molybdenum containing group called
molybdopterin.