BIOL 1510 Chapter 22 (pt 1)

Who do most nitrogen transformations?

Bacteria and archaea

Percentage of N2 in air

80%

Can N2 be used?

No. not by most living things. only a select few can do nitrogen fixation

Nitrogen cycle

N2→NH4+→NO2- → NO3-

What organisms can turn N2 into NH4+?

nitrogen fixing bacteria and archea

What organisms can turn NH4+ into NO2-?

nitrifying bacteria and archea

What organisms can turn NO2- into NO3-?

nitrifying bacteria

What organisms can turn NO3- back into N2?

denitrifying bacteria, archaea, and fungi

Oxidation state progression of nitrogen during fixation

0→ -3 → +3 → +5

What enzyme turns N2 into NH4+?

denitrogenase

Is nitrogen fixation into N4+ favorable?

Yes. But it takes high pressures and temperatures to achieve

Structure of denitrogenase

alpha2beta2 heterotetramer with two iron-containing cofactors

Denitrogenase cofactors

P clusters

FeMo cofactor

P clusters

clusters of 4Fe-4S

FeMo cofactor

iron, sulfur, molybdenum/vanadium