title: Temperature and Ca(2+)-dependence of the sarcoplasmic reticulum Ca(2+)-ATPase in haddock, salmon, rainbow trout and zebra cichlid.
abstract: Temperature dependence of Ca(2+)-ATPase from the sarcoplasmic reticulum (SR) in rabbit muscle has been widely studied, and it is generally accepted that a break point in Arrhenius plot exist at approximately 20 degrees C. Whether the break point arises as a result of temperature dependent changes in the enzyme or its membrane lipid environment is still a matter of discussion. In this study we compared the temperature dependence and Ca(2+)-dependence of SR Ca(2+)-ATPase in haddock (Melanogrammus aeglefinus), salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss) and zebra cichlid (Cichlasoma nigrofasciatum). The Arrhenius plot of zebra cichlid showed a break point at 20 degrees C, and the haddock Arrhenius plot was non-linear with pronounced changes in slope in the temperature area, 6-14 degrees C. In Arrhenius plot from both salmon and rainbow trout a plateau exists with an almost constant SR Ca(2+)-ATPase activity. The temperature range of the plateau was 14-21 and 18-25 degrees C in salmon and rainbow trout, respectively. Ca(2+)-dependence in the four different fish species investigated was very similar with half maximal activation (K(0.5)) between 0.2 and 0.6 micro M and half maximal inhibition (I(0.5)) between 60 and 250 micro M. Results indicated that interaction between SR Ca(2+)-ATPase and its lipid environment may play an important role for the different Arrhenius plot of the different types of fish species investigated.
authors.affiliation: Danish Institute for Fisheries Research, Department of Seafood Research, Technical University of Denmark, Building 221, DK-2800, Lyngby, Denmark. hgo@dfu.min.dk
authors.forename: Helene
authors.initials: H
authors.lastname: Godiksen
authors.forename: Flemming
authors.initials: F
authors.lastname: Jessen
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D023681:Cichlids; D005399:Fishes; D007700:Kinetics; D017686:Oncorhynchus mykiss; D012474:Salmon; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D013696:Temperature; D013816:Thermodynamics
chemical_list: D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D002118:Calcium