Family C47


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family C47

NamePeptidase family C47 (staphopain family)
Family type peptidaseC47.001 - staphopain A (Staphylococcus aureus), MEROPS Accession MER0061229 (peptidase unit: 215-388)
Content of familyPeptidase family C47 contains endopeptidases.
History Identifier created: MEROPS 3.1 (22 December 1998)
Peptidase activity found in the Staphylococcus aureus culture medium dependent on reducing agents was first described by Arvidson (1973). The peptidase was later purified and classified as a papain-like cysteine peptidase (Arvidson et al., 1973) with broad specificity (Bjorklind & Jornvall, 1974).
Catalytic typeCysteine
Active site residuesQ232 C238 H334 N355 
Active siteCys24 and His120 form the catalytic dyad with Asn141 interacting with His120. Gln18 is involved in the formation of the oxyanion hole.
Activities and specificitiesStaphopain A shows a broad specificity on horse liver alcohol dehydrogenase (Bjorklind & Jornvall, 1974). Assay substrates are Z-Phe-Leu-GluNHPhNO2 and Z-Phe-ArgNHMec, although haemoglobin and casein may also be used. Staphopain B differs from staphopain A in its more restricted specificity.
InhibitorsStaphopains A and B are inhibited by staphostatins A (I58.001) and B (I57.001) respectively. It is believed that the staphostatins produced by Staphylococcus aureus prevent degradation of the Staphylococcus cytoplasmic proteins by prematurely activated prostaphopains. Other inhibitors include E64 and cystatin A (I25.001), as well as heavy metals and oxidising agents (Potempa & Travis, 2004).
Molecular structureThe structure of staphopain contains two domains. The N-terminal domain contains four alpha-helices whilst the C-terminal domain forms an eight-stranded antiparallel beta-barrel. The active site residues are found in a cleft between the two domains. The fold of staphopain resembles that of papain, despite the lack of sequence similarity (Hofmann et al., 1993).
Basis of clan assignmentProtein fold of the peptidase unit for members of this family and resembles that of papain, the type example for clan CA.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses -  
Biological functionsThe staphopains are suggested to be important for the survival of Staphylococcus sp. in vivo, and inhibition of staphopain activity inhibits the growth of the bacteria in vitro Potempa & Travis, 2004.
Pharmaceutical and biotech relevanceGenetic characterization of staphopain genes in Staphylococcus aureus suggests that the staphopains have important housekeeping and/or virulence functions, and therefore may constitute a target for the development of therapeutic inhibitors for the treatment of staphylococcal diseases (Golonka et al., 2004).
ReviewsPotempa & Travis (2004)
Statistics for family C47Sequences:28
Identifiers with PDB entries:2
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
staphopain AC47.001Yes
staphopain BC47.002Yes
ecp peptidaseC47.003-
staphopain CC47.004-
family C47 non-peptidase homologuesnon-peptidase homologue-
family C47 unassigned peptidasesunassigned-