title: Purification and characterization of thaumatopain, a cysteine protease from the arils of the plant Thaumatococcus daniellii.
abstract: Aqueous extracts of the aril of the seed of Thaumatococcus daniellii contain, in addition to the intensely sweet protein thaumatin, a cysteine protease that we have termed thaumatopain. Thaumatopain has been purified by ion-exchange chromatography from arils, and is a monomeric protein of Mr 30,000. The protease strongly resembles papain in proteolytic activity, pH optima, susceptibility to inhibitors of cysteine proteases and in N-terminal sequence. The protease has also been identified in crude aril extracts by affinity labelling with iodo[14C]acetate. Thaumatopain is responsible for the cysteine protease activity previously attributed to thaumatin. Thaumatin is digested by thaumatopain at neutral to alkaline pH values.
authors.affiliation: Department of Biochemistry, University of Liverpool, U.K.
authors.forename: M
authors.initials: M
authors.lastname: Cusack
authors.forename: A G
authors.initials: AG
authors.lastname: Stephen
authors.forename: R
authors.initials: R
authors.lastname: Powls
authors.forename: R J
authors.initials: RJ
authors.lastname: Beynon
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002852:Chromatography, Ion Exchange; D003546:Cysteine Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007328:Insulin / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000201:enzymology*; D013379:Substrate Specificity; D013549:Sweetening Agents
chemical_list: D007328:Insulin; D010940:Plant Proteins; D013549:Sweetening Agents; C003427:thaumatin protein, plant; D003546:Cysteine Endopeptidases; C067611:thaumatopain