Dipeptidyl peptidase I is involved in the activation of a number of disease-related proteases by removal of N-terminal prodipeptides. We here report a selective activity-based probe for monitoring dipeptidyl peptidase I activity in whole proteomes as well as in intact cells, without labeling of closely related enzyme family members.

ICP is a chagasin-family natural tight binding inhibitor of Clan CA, family C1 cysteine peptidases (CPs). We investigated the role of ICP in Trypanosoma brucei by generating bloodstream form ICP-deficient mutants (Deltaicp). A threefold increase in CP activity was detected in lysates of Deltaicp, which was restored to the levels in wild type parasites by re-expression of the gene in the null mu...

Cysteine peptidases play a central role in the biology of Leishmania. In this work, we sought to further elucidate the mechanism(s) by which the cysteine peptidase CPB contributes to L. mexicana virulence and whether CPB participates in the formation of large communal parasitophorous vacuoles induced by these parasites. We initially examined the impact of L. mexicana infection on the traffickin...

Cystatins are natural inhibitors of papain-like (family C1) and legumain-related (family C13) cysteine peptidases. Cystatin D is a type 2 cystatin, a secreted inhibitor found in human saliva and tear fluid. Compared with its homologues, cystatin D presents an unusual inhibition profile with a preferential inhibition cathepsin S > cathepsin H > cathepsin L and no inhibition of cathepsin B or pig...

Antimicrobial proteins (peptides) are known to play important roles in the innate host defense mechanisms of most living organisms, including plants, insects, amphibians and mammals. They are also known to possess potent antibiotic activity against bacteria, fungi, and even certain viruses. Recently, the rapid emergence of microbial pathogens that are resistant to currently available antibiotic...

Background: Ram sperm have a higher polyunsaturated fatty acids and a lower cholesterol/phospholipid ratio than other species which renders the sperm much more vulnerable to oxidative damage caused by reactive oxygen species (ROS). Oxidative stress can affects the integrity of cells at both the structural and sub structural levels. Therefore, a suitable antioxidant may prevent cryo-injuries and...

Dipeptidyl peptidase I (DPPI) is a lysosomal cysteine protease that has been implicated in the processing of granzymes, which are neutral serine proteases exclusively expressed in the granules of activated cytotoxic lymphocytes. In this report, we show that cytotoxic lymphocytes derived from DPPI-/- mice contain normal amounts of granzymes A and B, but these molecules retain their prodipeptide ...