This entry refers to a domain found in uncharacterized subtilisin homologues from bacteria, including KerA from Streptomyces.This domain is part of a family of domains found in serine peptidases belonging to the MEROPS peptidase families S8 (subfamilies S8A (subtilisin) and S8B (kexin)) and S53 (sedolisin), both of which are members of clan SB [, , , ].Peptidases S8 (or subtilases serine endo- and exo-peptidase clan) have an Asp/His/Ser catalytic triad similar to that found in trypsin-like proteases, but do not share their three-dimensional structure and are not homologous to trypsin. The stability of subtilases may be enhanced by calcium, some members have been shown to bind up to 4 ions via binding sites with different affinity. Some members of this clan contain disulfide bonds. These enzymes can be intra- and extracellular, some function at extreme temperatures and pH values [, , , ].
