title: Aspartic proteinases in Antarctic fish.
abstract: The present review surveys several recent studies of the aspartic proteinases from Antarctic Notothenioidei, a dominating fish group that has developed a number of adjustments at the molecular level to maintain metabolic function at low temperatures. Given the unique peculiarities of the Antarctic environment, studying the features of Antarctic aspartic proteinases could provide new insights into the role of these proteins in fish physiology. We describe here: (1) the biochemical properties of a cathepsin D purified from the liver of the hemoglobinless icefish Chionodraco hamatus; (2) the biochemical characterization of Trematomus bernacchii pepsins variants A1 and A2 obtained by heterologous expression in bacteria; and (3) the identification of two closely related, novel aspartic proteinases from the liver of the two Antarctic fish species mentioned above. Overall, the results show that Notothenioidei aspartic proteinases display a number of characteristics that are remarkably different from those of mammalian aspartic proteinases, including high turnover number or high catalytic efficiency. We have named the newly identified aspartic proteinases "Nothepsins" and classified them relative to aspartic proteinases from other species.
authors.affiliation: CNR, Institute of Protein Biochemistry, Via P. Castellino 111-80131, Naples, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: De Luca
authors.forename: Giovanna
authors.initials: G
authors.lastname: Maria
authors.forename: Gaia
authors.initials: G
authors.lastname: De Mauro
authors.forename: Giuliana
authors.initials: G
authors.lastname: Catara
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carginale
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ruggiero
authors.forename: Antonio
authors.initials: A
authors.lastname: Capasso
authors.forename: Elio
authors.initials: E
authors.lastname: Parisi
authors.forename: Sebastien
authors.initials: S
authors.lastname: Brier
authors.forename: John R
authors.initials: JR
authors.lastname: Engen
authors.forename: Clemente
authors.initials: C
authors.lastname: Capasso