title: Release of a newly-identified cysteine protease, tetrain, from Tetrahymena into culture medium during the cell growth.
abstract: Protease activity in the culture medium of Tetrahymena pyriformis markedly increased during the growth of the ciliate. The protease activity in the culture medium was purified by sequential column chromatographies. The purified protease had an apparent molecular mass of 28 kDa. N-terminal amino acid sequencing analysis suggested that the protease is a mature form of cysteine protease. Requirements of free sulfhydryl groups for activity and sensitivity to N-tosyl-L-phenylalanine chloromethyl ketone and Na-p-tosyl-L-lysine chloromethyl ketone also indicated that the protease is a member of the papain family of cysteine proteases. The protease was designated as tetrain. Immunoblotting analyses showed that tetrain was present in higher amount in the culture medium in the stationary phase than in the logarithmic phase. Tetrain has high activities at neutral to alkaline pH values. This suggests that tetrain has functional roles in the culture medium in the stationary phase, because the pH of the culture medium became alkaline with the progress of Tetrahymena growth.
authors.affiliation: Department of Biological Science, Faculty of Science, Hiroshima University, Higashi-Hiroshima.
authors.forename: K M
authors.initials: KM
authors.lastname: Suzuki
authors.forename: N
authors.initials: N
authors.lastname: Hosoya
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Kosaka
authors.forename: H
authors.initials: H
authors.lastname: Hosoya
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division / Q000502:physiology; D003470:Culture Media / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013769:Tetrahymena pyriformis / Q000737:chemistry / Q000201:enzymology* / Q000254:growth & development*
chemical_list: D003470:Culture Media; D017077:Culture Media, Conditioned; D015853:Cysteine Proteinase Inhibitors; D013439:Sulfhydryl Reagents; D003546:Cysteine Endopeptidases; C106859:tetrain; D004229:Dithiothreitol