BLMH/Bleomycin Hydrolase: Lysates

Bleomycin hydrolase (BLMH) is a cysteine peptidase of the papain superfamily. It is named for its ability to hydrolyze the anti-tumor agent bleomycin and inactivate it. It has a papain-like catalytic triad (Cys-His-Asp) with optimum activity at neutral pH. In mammals it is expressed ubiquitously in all types of tissues and its expression is up-regulated in many tumors. It is present in the cytoplasm as homohexameric protein of approximately 300 kDa. In addition to its aminopeptidase activity, it has homocysteine-thiolactonase activity. The normal physiological function of BLMH is not clear. BLMH inactivates bleomycin, a glycopeptide anti-cancer agent, by deaminating it. BLMH has been suggested to play a role in the generation of MHC class I-presented peptides. Diminished BLMH activity may contribute to the pathology of Alzheimer's disease. It is inhibited by cysteine protease inhibitors such as N-ethylmaleimide, iodoacetamide, para-hydroxymercuribenzoate, and E-64.