Localization of inhibition by adenosine diphosphate of phosphoglycerate-dependent oxygen evolution in a reconstituted chloroplast system.
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ABSTRACT:
SUBMITTER: Slabas AR
PROVIDER: S-EPMC1172691 | biostudies-other | 1976 Jan
REPOSITORIES: biostudies-other
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Project description:The concentrations of ADP and ATP were measured during illumination of a reconstituted chloroplast system to which NADP(+), 3-phosphoglycerate and ribose 5-phosphate were successively added. Their effects on photosynthetic oxygen evolution and on the concentrations of ATP and ADP are discussed in terms of the regulation of photosynthetic carbon assimilation.
| S-EPMC1154216 | biostudies-other
Project description:Our early efforts to find a covalent inhibitor of mortalin, a member of the 70 kD heat shock protein (Hsp70) family, led us to solve the structure of the mortalin nucleotide-binding domain (NBD) in complex with N6-propargyladenosine-5'-diphosphate. The acquired structure emphasizes the ability of the nucleotide-binding pocket to accommodate modified ADP compounds. A library of ADP analogs modified at either the 2- or N6-positions of adenosine was screened against the mortalin-NBD. Competitive inhibition and binding assays of the analogs demonstrate that modifications at the 2- or N6-positions have potential to bind and inhibit mortalin uniquely compared to other Hsp70 homologs, and that modifications at the 2-position confer the greatest selectivity in binding and inhibition of the mortalin-NBD.
| S-EPMC6690775 | biostudies-literature
Project description:Phosphorylation of the light-harvesting chlorophyll protein (LHCP) by the thylakoid protein kinase has been examined in the reconstituted chloroplast system. The level of phosphorylation by [32P]Pi was maximal at high light intensity and in the absence of 3-phosphoglycerate; dephosphorylation resulted from a subsequent decrease in light intensity or from the addition of 3-phosphoglycerate. Addition of ribose 5-phosphate, which acts as an ATP 'sink', also caused dephosphorylation. It is concluded that the degree of phosphorylation is dependent on the redox state and energy state of the system, thereby providing a mechanism for adapting light harvesting to the demands of carbon assimilation.
| S-EPMC1154252 | biostudies-other
Project description:BackgroundAcute respiratory distress syndrome (ARDS) is a severe form of lung injury that frequently occurs during pneumonia and sepsis. Lung inflammation in ARDS patients may have deleterious effects on remote organs such as the kidney. The nuclear enzyme poly(adenosine diphosphate-ribose) polymerase (PARP) enhances the nuclear factor (NF)-?B-dependent transcription of inflammatory cytokines. This study was conducted to elucidate two questions: first, whether the activation of PARP and NF-?B mediates the renal inflammation secondary to the lipopolysaccharide (LPS)-induced acute lung inflammation; second, whether a PARP inhibitor, 3-aminobenzamide (3-AB), attenuates lung and kidney inflammation by inhibiting NF-?B-dependent proinflammatory cytokines.MethodsMale Sprague-Dawley rats were anesthetized, ventilated, and divided into three groups; a control group (n?=?8); an LPS group (n?=?12) intratracheally instilled with LPS (16 mg/kg), and an LPS?+?3-AB group (n?=?12) given the same dose of LPS by the same method followed by an intravenous injection of 3-AB (20 mg/kg). Hemodynamics, arterial blood gas, and the plasma levels of lactate, creatinine and potassium were measured at 0,1,2,3, and 4 h after treatment. The lung wet/dry ratio was measured at 4 h. The mRNA expression of tumor necrosis factor (TNF)-?, interleukin (IL)-1? and IL-6 in the lung and kidney were measured by TaqMan real-time PCR. PARP and NF-?B in the lung and kidney were histologically examined by immunostaining and assigned expression scores.ResultsLPS induced metabolic acidosis, hypotension, hypoxemia, increased the lung wet/dry ratio, increased the plasma levels of creatinine and potassium, and increased the cytokine mRNA expressions in the lung and kidney. All of these effects were associated with strong expression of PARP and NF-?B. Treatment with 3-AB prevented the LPS-induced metabolic acidosis and hypotension, reduced the plasma levels of lactate, creatinine and potassium, reduced the cytokine mRNA expressions, reduced the expression of PARP and NF-?B, improved pulmonary edema and oxygenation and preserved renal function.ConclusionsThe PARP inhibition attenuated lung-kidney crosstalk induced by intratracheal LPS instillation, partly via an inhibition of NF-?B dependent proinflammatory cytokines.
| S-EPMC3833186 | biostudies-literature
Project description:Recently, the development of poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors as a synthetic lethality approach has brought a major breakthrough in the treatment of breast cancer susceptibility gene (BRCA)-mutant cancers. Because sporadic cancers have also been found to commonly have other defects in DNA repair, PARP inhibitors are under active clinical investigation in combination with DNA-damaging therapeutics in a wide range of sporadic cancers. In this review, the authors discuss DNA repair mechanisms and PARP as a therapeutic target and summarize an update on clinical trials of available PARP inhibitors and predictive biomarkers for their efficacy.
| S-EPMC3600582 | biostudies-literature
Project description:Extracellular nucleotides act as paracrine regulators of cellular signaling and metabolic pathways. Adenosine polyphosphate (adenosine triphosphate (ATP) and adenosine diphosphate (ADP)) release and metabolism by human hepatic carcinoma cells was therefore evaluated. Hepatic cells maintain static nanomolar concentrations of extracellular ATP and ADP levels until stress or nutrient deprivation stimulates a rapid burst of nucleotide release. Reducing the levels of media serum or glucose has no effect on ATP levels, but stimulates ADP release by up to 10-fold. Extracellular ADP is then metabolized or degraded and media ADP levels fall to basal levels within 2-4 h. Nucleotide release from hepatic cells is stimulated by the Ca(2+) ionophore, ionomycin, and by the P2 receptor agonist, 2'3'-O-(4-benzoyl-benzoyl)-adenosine 5'-triphosphate (BzATP). Ionomycin (10 ?M) has a minimal effect on ATP release, but doubles media ADP levels at 5 min. In contrast, BzATP (10-100 ?M) increases both ATP and ADP levels by over 100-fold at 5 min. Ion channel purinergic receptor P2X7 and P2X4 gene silencing with small interference RNA (siRNA) and treatment with the P2X inhibitor, A438079 (100 ?M), decrease ADP release from hepatic cells, but have no effect on ATP. P2X inhibitors and siRNA have no effect on BzATP-stimulated nucleotide release. ADP release from human hepatic carcinoma cells is therefore regulated by P2X receptors and intracellular Ca(2+) levels. Extracellular ADP levels increase as a consequence of a cellular stress response resulting from serum or glucose deprivation.
| S-EPMC4272363 | biostudies-literature
Project description:Unlike currently approved adenosine diphosphate receptor antagonists, the new diadenosine tetraphosphate derivative GLS-409 targets not only P2Y12 but also the second human platelet adenosine diphosphate receptor P2Y1 and may, therefore, be a promising antiplatelet drug candidate. The current study is the first to investigate the in vivo antithrombotic effects of GLS-409.We studied (1) the in vivo effects of GLS-409 on agonist-stimulated platelet aggregation in anesthetized rats, (2) the antithrombotic activity of GLS-409 and the associated effect on the bleeding time in a canine model of platelet-mediated coronary artery thrombosis, and (3) the inhibition of agonist-stimulated platelet aggregation by GLS-409 versus selective P2Y1 and P2Y12 inhibition in vitro in samples from healthy human subjects before and 2 hours after aspirin intake. In vivo treatment with GLS-409 significantly inhibited adenosine diphosphate- and collagen-stimulated platelet aggregation in rats. Further, GLS-409 attenuated cyclic flow variation, that is, platelet-mediated thrombosis, in vivo in our canine model of unstable angina. The improvement in coronary patency was accompanied by a nonsignificant 30% increase in bleeding time. Of note, GLS-409 exerted its effects without affecting rat and canine hemodynamics. Finally, in vitro treatment with GLS-409 showed effects similar to that of cangrelor and the combination of cangrelor with the selective P2Y1 inhibitor MRS 2179 on agonist-stimulated platelet aggregation in human platelet-rich plasma and whole blood before and 2 hours after aspirin intake.Synergistic inhibition of both P2Y1 and P2Y12 adenosine diphosphate receptors by GLS-409 immediately attenuates platelet-mediated thrombosis and effectively blocks agonist-stimulated platelet aggregation irrespective of concomitant aspirin therapy.
| S-EPMC4767596 | biostudies-literature
Project description:Understanding mass transfer processes concomitant with electrochemical conversion for gas evolution reactions at the electrode-electrolyte interface plays a key role in advancing renewable energy storage and conversion. However, due to the complicated diffusion behavior of gas at the dynamic catalytic interfaces, it is still a great challenge to accurately portray mass transfer of gas during electrocatalysis process. Here, we track the diffusion of dissolved oxygen on Cu nanostructured plasmonic interface, which reveals multistage oxygen diffusion behaviors, including premature oxygen accumulation, spontaneous diffusion and accelerated oxygen dissipation. This work uncovers an accumulating inhibition effect on oxygen evolution arising from interfacial dissolved oxygen. With these knowledges, we develop a programmable potential scan strategy to eliminate interfacial gas products, which alleviates the concentration polarization, releases accessible actives sites and promotes electrocatalytic performance. Our findings provide a direct observation of the interfacial mass transfer processes that governs the kinetics of gas-involved multiphases catalysis.
| S-EPMC8041856 | biostudies-literature
Project description:When rat liver nuclei were incubated with [adenine-3H]NAD, besides histone 1, histone 2A and especially histone 2B accepted 3H radioactivity. 3H radioactivity was also found on the non-histone proteins and on the small amounts of histones 1 and 3 released into the supernatant during incubation. [14C]Adenine uptake in vivo by liver and thymus nuclei showed radioactivity in histones 1 and 3. After digestion with Pronase and leucine aminopeptidase 14C- or 32P-labelled histone 3 released a serine phosphate-containing nucleotide, which on acid hydrolysis yielded ADP-ribose and serine phosphate. Serine phosphate was also found in the material from the nucleotide peaks from histones 2A and 2B. ADP-ribosylated histones 1 and 3 were more easily released from nuclei than their unmodified forms and showed higher [32P]Pi and [3H]lysine uptakes in vivo [Ord & Stocken (1975) FEBS Meet. Proc. 34, 113-125].
| S-EPMC1164544 | biostudies-other
Project description:An adenosine diphosphate sugar pyrophosphatase (ASPPase, EC ) has been characterized by using Escherichia coli. This enzyme, whose activities in the cell are inversely correlated with the intracellular glycogen content and the glucose concentration in the culture medium, hydrolyzes ADP-glucose, the precursor molecule of glycogen biosynthesis. ASPPase was purified to apparent homogeneity (over 3,000-fold), and sequence analyses revealed that it is a member of the ubiquitously distributed group of nucleotide pyrophosphatases designated as "nudix" hydrolases. Insertional mutagenesis experiments leading to the inactivation of the ASPPase encoding gene, aspP, produced cells with marginally low enzymatic activities and higher glycogen content than wild-type bacteria. aspP was cloned into an expression vector and introduced into E. coli. Transformed cells were shown to contain a dramatically reduced amount of glycogen, as compared with the untransformed bacteria. No pleiotropic changes in the bacterial growth occurred in both the aspP-overexpressing and aspP-deficient strains. The overall results pinpoint the reaction catalyzed by ASPPase as a potential step of regulating glycogen biosynthesis in E. coli.
| S-EPMC35479 | biostudies-literature