title: Isolation and identification of a proteinase from calf thymus that cleaves poly(ADP-ribose) polymerase and histone H1.
abstract: A proteinase was isolated from calf thymus that degraded pADPRT, histone H1 and alpha-casein in a Ca(2+)-dependent manner. In a five-step procedure, a homogenous proteinase was obtained with a subunit structure of 80 and 30 kDa. The amino-acid homology of an internal sequence as well as kinetic and inhibitor assays identified the proteinase as calpain I. It is suggested that even though the general substrate alpha-casein is widely used for the assaying of calpains, more appropriately physiological cellular components (pADPRT and histone H1) specify the thymus proteinase.
authors.affiliation: Octamer Research Foundation, Romberg Tiburon Centers, San Francisco State University, CA 94920, USA. kg_buki@sfsu.edu
authors.forename: K G
authors.initials: KG
authors.lastname: Buki
authors.forename: P I
authors.initials: PI
authors.lastname: Bauer
authors.forename: E
authors.initials: E
authors.lastname: Kun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002154:Calpain / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002364:Caseins / Q000378:metabolism; D002417:Cattle; D002846:Chromatography, Affinity; D002848:Chromatography, DEAE-Cellulose; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013552:Swine; D013950:Thymus Gland / Q000201:enzymology*
chemical_list: D002364:Caseins; D006657:Histones; D011065:Poly(ADP-ribose) Polymerases; D002154:Calpain; D002118:Calcium