title: Cathepsin S and cruzipain are inhibited by equistatin from Actinia equina.
abstract: Cathepsin S has been isolated for the first time from human tissue. It has a molecular mass of 24 kDa and an isoelectric point in the range of 8.2 to 8.6. The enzyme is inhibited by equistatin, which belongs to the thyropins, a new family of protein inhibitors, with an inhibition constant of Ki = 0.40 +/- 0.07 nM. Cruzipain, a cathepsin L-like enzyme sharing a 130 amino acid long C-terminal extension, is also strongly inhibited by equistatin (Ki = 0.028 +/- 0.006 nM). Together with previously reported data, these results further indicate that a functional heterogeneity exists among thyropin inhibitors, as demonstrated by their interaction with cathepsin S and cruzipain.
authors.affiliation: Department of Biochemistry and Molecular Biology, J. Stefan Institute, Ljubljana, Slovenia.
authors.forename: V
authors.initials: V
authors.lastname: Stoka
authors.forename: B
authors.initials: B
authors.lastname: Lenarcic
authors.forename: J J
authors.initials: JJ
authors.lastname: Cazzulo
authors.forename: V
authors.initials: V
authors.lastname: Turk
mesh_terms: D000818:Animals; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D002852:Chromatography, Ion Exchange; D003546:Cysteine Endopeptidases / Q000187:drug effects*; D015853:Cysteine Proteinase Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007525:Isoelectric Focusing; D007700:Kinetics; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D015800:Protozoan Proteins; D012615:Sea Anemones / Q000737:chemistry*
chemical_list: D015853:Cysteine Proteinase Inhibitors; D011506:Proteins; D015800:Protozoan Proteins; C106356:equistatin; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C028217:cathepsin S; C063214:cruzipain