Electron affinity: The enthalpy change that results from adding an electron to a gaseous atom.

Electron affinity is becoming less negative (less exothermic) and less likely to gain an electron. 

TLS Online TPP Program

#Id: 9267

#Section 2: General Biology

Diazotrophs are able to catalyze the enzymatic reduction of this compound to ammonia (NH3) using the enzyme nitrogenase

TLS Online TPP Program

#Id: 9268

#Section 2: General Biology

Nitrogenase is a complex consisting of the MoFe protein (dinitrogenase or component I) a heterotetramer, and the Fe protein (dinitrogenase reductase or component II) a homodimer.

TLS Online TPP Program

#Id: 9269

#Section 2: General Biology

Fe protein 

contains 2 identical subunits (dimer) – nif H

Each subunit has MW of 30 ~ 72 kD.

Each subunit contains an Fe-S cluster (4Fe and 4S2-).

TLS Online TPP Program

#Id: 9270

#Section 2: General Biology

MoFe protein 

2 pairs of identical subunits (tetramer, nif D & nif K)

A total of MW 180 ~ 235kD

Each subunit has 2 Mo-Fe-S clusters.

Both Fe proteins and MoFe proteins are sensitive to O2. 

TLS Online TPP Program

#Id: 9271

#Section 2: General Biology

TLS Online TPP Program

#Id: 9272

#Section 2: General Biology