Introduction:
Metalloproteins are proteins that contain a metal ion cofactor in their structure. These metal ions are essential for the protein's function, and they play a crucial role in catalysis, electron transfer, and other biological processes. Among the metalloproteins, rubredoxin, 2-iron ferredoxin, and 4-iron ferredoxin are well-known examples.

Rubredoxin:
Rubredoxin is a small metalloprotein that contains a single iron atom in its active site. The iron atom is coordinated by four cysteine residues, which provide the ligands for the metal ion. There are no inorganic sulfur atoms present in the metalloprotein active site of rubredoxin.

2-Iron Ferredoxin:
2-Iron ferredoxin is a metalloprotein that contains two iron atoms in its active site. The iron atoms are coordinated by four cysteine residues and two inorganic sulfur atoms, which provide the ligands for the metal ions. Therefore, there are two inorganic sulfur atoms present in the metalloprotein active site of 2-iron ferredoxin.

4-Iron Ferredoxin:
4-Iron ferredoxin is a metalloprotein that contains four iron atoms in its active site. The iron atoms are coordinated by eight cysteine residues and four inorganic sulfur atoms, which provide the ligands for the metal ions. Therefore, there are four inorganic sulfur atoms present in the metalloprotein active site of 4-iron ferredoxin.

Conclusion:
In summary, rubredoxin contains no inorganic sulfur atoms in its active site, while 2-iron ferredoxin and 4-iron ferredoxin contain two and four inorganic sulfur atoms, respectively. The presence of these inorganic sulfur atoms is essential for the function of these metalloproteins, and they play a crucial role in stabilizing the metal ion cofactors and facilitating electron transfer reactions.