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Mitochondria of Saccharomyces cerevisiae lack the respiratory complex I, but contain three rotenone‐insensitive NADH dehydrogenases distributed on both the external (Nde1 and Nde2) and internal (Ndi1) surfaces of the inner mitochondrial membrane. These enzymes catalyse the transfer of electrons from NADH to ubiquinone without the translocation of protons across the membrane. Due to the high resolution...
Escherichia coli is recognized as an etiological bacteria associated with chorioamnionitis and the preterm premature rupture of fetal membranes. This pathological condition induces pro-inflammatory cytokines and degradative metalloproteinases, which are considered biological markers secreted in an acute stage of infection. Heat-shock proteins (HSPs) are an important component of the innate immunity...
Protein phosphorylation plays an important role in the modulation of steroidogenesis and it depends on the activation of different signaling cascades. Previous data showed that PKA activity is related to steroidogenesis in mitochondria from syncytiotrophoblast of human placenta (HPM). PKA localization and contribution in progesterone synthesis and protein phosphorylation of HPM was assessed in this...
The human placenta, which does not express the StAR protein, synthesizes large amounts of progesterone. The rate-limiting step for steroidogenesis is the transport of cholesterol which is divided into two steps: 1) cholesterol flux from cytoplasm to outer membrane mitochondria, and 2) cholesterol transport from outer to inner mitochondrial membrane. The proteins mediating placental cholesterol influx...
The role of K + on steroidogenesis in isolated mitochondria from the human placenta was explored. Cholesterol uptake and progesterone synthesis were stimulated by K + , and by the further addition of ATP. In the presence of glibenclamide or quinine (inhibitors of the K + channel mito-K ATP ), the synthesis of progesterone was improved, indicating that K + acts...
The human placental mitochondria have an ATP-diphosphohydrolase (apyrase) activity. In this paper we characterized the effect of 5'-p-fluorosulfonylbenzoyl adenosine (FSBA) on placental apyrase, and its repercussion on progesterone synthesis and oxygen consumption. Apyrase activity was inhibited by FSBA. Nucleosides tri- and diphosphates protected against FSBA inactivation, but divalent cations did...
This report describes an ATP-diphosphohydrolase activity associated with the inner membrane of human term placental mitochondria. An enriched fraction containing 30 per cent of the total protein and 80 per cent of the total ATP-diphosphohydrolase activity was obtained from submitochondrial particles. ATP-diphosphohydrolase activity was characterized in this fraction. The enzyme had a pH optimum of...
Cholesterol transport for steroidogenesis in the human placental mitochondria is an enigma as, contrary to other steroidogenic tissues, the human placenta does not express steroidogenic acute regulatory protein (StAR), a protein known to be required for efficient utilization of cholesterol by adrenal and gonadal mitochondria. These observations suggest the possibility that cholesterol transport in...
In a previous study we demonstrated the existence of a tightly-bound ATPase in the human placental mitochondria (Martinez et al., 1993). The current study characterizes the ATP hydrolysis produced by the F 1 F 0 -ATPase and the tightly-bound ATPase in submitochondrial particles from the human term placenta. Both enzymes were not differentiated by pH. Inhibitors were necessary to distinguish...
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