Table 1. Summary of selected cofactors within structures deposited in the PDB archive (June 2010).

Prototypical protein example	Cofactor or chromophore	λmax (nm)	Typical ∊ (mM−1 cm−1)	PDB ligand ID or name	No. of PDB structures
Aspartate aminotransferase	Pyridoxal-5′-phosphate	350, 412	6.6, 9.5	PLP	568
Lactate dehydrogenase	NAD(H) or NADP(H)	340	6.2	NAD, NDP, NAP	1480
Dihydrofolate reductase	Pterin	350	4.5	Pterin	242
p-Hydroxybenzoate hydroxylase	FAD or FMN	450	11	FAD, FMN, flavin	1466
Myoglobin	Heme	409	170	Hem	2262
Mn superoxide dismutase	Mn(III)-O/N	480	0.91	Mn	1395
Rubredoxin	Fe (non-heme)	430–500	3–5	Fe	766
Ferredoxin	Fe2/S2 cluster	∼400	30.6	FeS	304
High potential iron protein	Fe4/S4 cluster	∼400	15	SF4	388
Methylmalonyl-CoA mutase	Co or B12	360	27.5	Cobalt	355
Urease	Ni(II)-O/N	407	0.21	Nickel	461
Azurin or plastocyanin	Cu	600	5	Cu	752
Photosynthetic reaction center	Chlorophyll	465, 665	>100	BCL, BPH, etc.	147
Bacteriorhodopsin	Retinal	480	27	Ret	111
Green fluorescent protein	Post-translation modification	350–700	6–94.5	Luminescent proteins	218