Spermine, another specific allosteric activator of calcium uptake in rat liver mitochondria.
Calcium uptake in rat liver mitochondria is accelerated by spermine. At a concentration of 2 microM Ca2+ and 1 mM Mg2+ a maximal, 10-fold activation by 1.2 mM spermidine was obtained; a half-maximal activation was attained with 0.2 mM spermine. Spermidine was far less effective than spermine whereas putrescine was ineffective. The acceleration of Ca uptake at low, physiological Ca2+ concentrations is related to the altered kinetics of the Ca uniporter. Corresponding to the alteration by high Ca2+ concentrations previously described, the kinetics changed from sigmoidal in the absence to nearly hyperbolic in the presence of spermine. Mg2+ behaves as an allosteric inhibitor. This phenomenon of the allosteric activation of Ca uptake could not be observed in heart mitochondria.
Kröner
H
H
Institut für Physiologische Chemie I, University of Düsseldorf, West Germany.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008929:Mitochondria, Heart / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D011700:Putrescine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013095:Spermidine / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology*
D013096:Spermine; D008274:Magnesium; D002118:Calcium; D013095:Spermidine; D011700:Putrescine