Polyamines improve Ca2+ transport system of the yeast mitochondria

Abstract

Spermine at concentrations of 12–100 μM considerably activates the Ca2+ transport system of the Endomyces magnusii yeast mitochondria. As a result, in the presence of spermine the mitochondria are able to decrease extramitochondrial Ca2+ to the physiological level. At Ca2+ concentrations up to 200 μM, spermine enhances the initial rate of Ca2+ uptake (a half-maximal effect at 12 μM spermine). The Ca2+ concentrations required for half-maximal Ca2+ uptake rate to be achieved were 160 and 60 μM Ca2+ without and with spermine, respectively. Spermidine is shown to be less effective (a half-maximal effect at 50–100 μM spermidine). The polyamines do not change the parameters of energy coupling of mitochondria. The data obtained enabled the yeast mitochondria to be considered to take part in regulation of cytoplasmic and matrix Ca2+