Inhibitory factor 1 (IF1) is one of the major regulators of mitochondrial ATP synthase activity, a key enzyme of energy metabolism. Its inhibitory effects are known in conditions such as hypoxia or starvation, but the hypothesis that IF1 inhibits ATP synthase activity even under physiological conditions is still not entirely accepted. Disorders of ATP synthase regulation can be fatal to the cell and have been described, for example, in carcinogenesis and ischemia. It has also been found that silencing of the IF1 gene in pancreatic β-cells increases insulin secretion, and thus, IF1 may be important in the pathogenesis of type 2 diabetes. The goal of this work is to summarize the current knowledge about the IF1 protein and to obtain new results that will help elucidate the mechanism by which this protein regulates mitochondrial ATP synthase. Specifically, this work deals with the ratio of IF1 protein to ATP synthase in pancreatic β-cells, depending on different culture conditions. It further investigates the occurrence of post-translational modifications of the IF1 protein in pancreatic β-cells (INS- 1E model cells), which may play a role in the regulation of IF1 activity. It also deals with the cellular ATP/ADP ratio, which is one of the key factors for insulin secretion by pancreatic β-cells. An...

In this paper we present the inhibitory effect of a variety of structurally modulated/modified polyphenolic compounds on purified F 1 or membrane bound F 1F o Escherichia coli ATP synthase. Structural modulation of polyphenols with two phenolic rings inhibited ATP synthase essentially completely; one or three ringed polyphenols individually or fused together inhibited partially. We found that the position of hydroxyl and nitro groups plays critical role in the degree of binding and inhibition of ATPase activity. The extended positioning of hydroxyl groups on imino diphenolic compounds diminished the inhibition and abridged position enhanced the inhibition potency. This was contrary to the effect by simple single ringed phenolic compounds where extended positioning of hydroxyl group was found to be effective for inhibition. Also, introduction of nitro group augmented the inhibition on molar scale in comparison to the inhibition by resveratrol but addition of phosphate group did not. Similarly, aromatic diol or triol with rigid or planar ring structure and no free rotation poorly inhibited the ATPase activity. The inhibition was identical in both F 1F o membrane preparations as well as in isolated purified F 1 and was reversible in all cases. Growth assays suggested that modulated compounds used in this study inhibited F 1-ATPase as well as ATP synthesis nearly equally.

The aim of this study was to determine if the dietary benefits of bioflavonoids are linked to the inhibition of ATP synthase. We studied the inhibitory effect of 17 bioflavonoid compounds on purified F1 or membrane bound F1Fo E. coli ATP synthase. We found that the extent of inhibition by bioflavonoid compounds was variable. Morin, silymarin, baicalein, silibinin, rimantadin, amantidin, or, epicatechin resulted in complete inhibition. The most potent inhibitors on molar scale were morin (IC50∼0.07mM)>silymarin (IC50∼0.11mM)>baicalein (IC50∼0.29mM)>silibinin (IC50∼0.34mM)>rimantadin (IC50∼2.0mM)>amantidin (IC50∼2.5mM)>epicatechin (IC50∼4.0mM). Inhibition by hesperidin, chrysin, kaempferol, diosmin, apigenin, genistein, or rutin was partial in the range of 40-60% and inhibition by galangin, daidzein, or luteolin was insignificant. The main skeleton, size, shape, geometry, and position of functional groups on inhibitors played important role in the effective inhibition of ATP synthase. In all cases inhibition was found fully reversible and identical in both F1Fo membrane preparations and isolated purified F1. ATPase and growth assays suggested that the bioflavonoid compounds used in this study inhibited F1-ATPase as well as ATP synthesis nearly equally, which signifies a link between the beneficial effects of dietary bioflavonoids and their inhibitory action on ATP synthase.

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ABSTRACT This thesis research involved investigations into the effects of inflammation on maturation of L-carnitine homeostasis in developing rat neonates. The overall hypothesis was an inflammatory stimulus will alter the ontogeny of L-carnitine homeostasis pathways and this depends upon when the inflammatory stimulus occurs in postnatal development. The objective was to investigate the potential effect of inflammation on carnitine transporter expression in different age groups of neonates and evaluation of effect of inflammation on ontogeny and activity of enzymes involved in carnitine biosynthesis and whether this differs depending upon when in postnatal development the inflammatory stimulus occurs. Rat pups at postnatal day 3, 7, and 14 received an intraperitoneal injection of lipopolysaccharide (LPS) at a dose known to cause a febrile reaction in rat neonates. L-Carnitine homeostasis pathways underwent significant ontogenesis during postnatal development in the rat. LPS administration caused a significant decrease in free L-carnitine levels in serum and heart tissue and a decrease in mRNA expression levels of the high affinity carnitine transporter, Octn2, in kidney, heart and intestine at all postnatal ages. Furthermore, significant decreases in mRNA expression levels of key enzymes involved in carnitine biosynthesis was observed, while an increase in carnitine palmitoyltransferase mRNA levels were observed at all postnatal ages. Reductions in butyrobetaine hydroxylase mRNA expression were paralleled by reductions in enzyme activity only at postnatal day 3 and 7. Heart creatine phosphate levels were deceased significantly in LPS treated groups in all postnatal ages; however, ADP and ATP levels were unaffected. Collectively, this research provided experimental evidence for a significant effect of inflammation on changes in L-carnitine homeostasis maturation in early neonatal stages. The maturation of physiological processes may be altered by external factors in early postnatal life.

Student Number : 9811492X - MSc dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / This dissertation discusses the development of an ATP model of a network to aid measurement techniques in a harmonic evaluation. A theoretical back- ground discussion of various pieces of equipment and their signi#12;cance to har- monics is included. National Electricity Regulator (NRS 048) standards are discussed with refer- ence to performing a basic investigation and short comings. A test study was performed on the Brandspruit Mine in Secunda. ATP models are developed for equipment relevant to the test case, these in- clude AC{AC converters, AC{DC converters, three phase transformers and cables. Finally the measured test case is compared to simulation results and conclusions drawn.

The complexes of oxidative phosphorylation (OXPHOS) are situated in the inner mitochondrial membrane in higher structural and functional complexes, so-called supercomplexes, which facilitates substrate channeling. ATP synthase is also able to organize in higher structures. In mammalian mitochondria, ATP synthase is usually present in a dimeric form. There is evidence of its trimerization and even tetramerization. Furthermore, it seems that ATP synthase catalyzing the phosphorylation of ADP to ATP, adenine nucleotide translocator (ANT) ensuring the exchange of ADP for newly synthesized ATP across the inner mitochondrial membrane and phosphate carrier (PiC) allowing the import of inorganic phosphate (Pi) into the matrix of mitochondria are assembled in a supercomplex called ATP synthasome. This association among the components of phosphorylative apparatus seems to increase the efficiency of processes leading to the ATP synthesis. First, we studied amounts of the components of phosphorylative apparatus in connection with various ATP synthase contents among mitochondria isolated from nine rat tissues. Mitochondrial proteins were separated by denaturing electrophoresis (SDS-PAGE) and their content was analyzed using specific antibodies. In agreement with our expectations, the highest content of...

Thesis advisor: Thomas C. Chiles / B-lymphocytes respond to environmental cues for their survival, growth, and differentiation through receptor-mediated signaling pathways. Naïve Blymphocytes must acquire and metabolize external glucose in order to support the bioenergetics associated with maintaining cell volume, ion gradients, and basal macromolecular synthesis. The up-regulation of glycolytic enzyme expression and activity via engaged B-cell receptor mediated-events was glucose-dependent. This suggests an essential role for glucose energy metabolism in the promotion of B cell growth, survival, and proliferation in response to extracellular stimuli. In addition, the activity of ATP-citrate lyase (ACL) was determined to be crucial for ex vivo splenic B cell differentiation to antibody-producing cells wherein B cells undergo endomembrane synthesis and expansion. This investigation employed knockout murine models as well as chemical inhibitors to determine the signaling components and enzymes responsible for glucose utilization and incorporation into membrane lipids. These results point to a critical role for phosphatidylinositol 3- kinase (PI3K) in orchestrating cellular glucose energy metabolism and glucosedependent de novo lipogenesis for B lymphocyte responses. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.