Search results for "ATP"

Vinorine synthase from Rauvolfia: the first example of crystallization and preliminary X-ray diffraction analysis of an enzyme of the BAHD superfamily

2004

Abstract Crystals of vinorine synthase (VS) from medicinal plant Rauvolfia serpentina expressed in Escherichia coli have been obtained by the hanging-drop technique at 305 K with ammonium sulfate and PEG 400 as precipitants. The enzyme is involved in the biosynthesis of the antiarrhythmic drug ajmaline and is a member of the BAHD superfamily of acyltransferases. So far, no three-dimensional structure of a member of this enzyme family is known. The crystals belong to the space group P 2 1 2 1 2 1 with cell dimensions of a =82.3 A, b =89.6 A and c =136.2 A. Under cryoconditions (120 K), a complete data set up to 2.8 A was collected at a synchrotron source.

Structural dynamics in F1ATPase during the first reaction cycle of ATP hydrolysis

1991

Abstract The velocity of ATP hydrolysis, catalyzed by purified F 1 ATPase from Micrococcus luteus , was decelerated on decreasing the temperature. At 13′C one reaction cycle is completed after 20 s. Hydrolysis was triggered upon rapid mixing of the enzyme with ATP. During the first reaction cycle, succeeding structural alterations of the F 1 ATPase were traced by time resolved X-ray scattering. The scattering spectra obtained from consecutive intervals of 1 s, revealed the F 1 ATPase to pass a conformational state exhibiting an expanded (6%) molecular shape. The expanded state was observed between 45% and 65% of the time required to complete the reaction cycle. This pointx out a conformatio…

6-mercaptopurine and 9-(2-phosphonyl-methoxyethyl) adenine (PMEA) transport altered by two missense mutations in the drug transporter gene ABCC4

2008

Multiple drug resistance protein 4 (MRP4, ABCC4) belongs to the C subfamily of the ATP-binding cassette (ABC) transporter superfamily and participates in the transport of diverse antiviral and chemotherapeutic agents such as 6-mercaptopurine (6-MP) and 9-(2-phosphonyl methoxyethyl) adenine (PMEA). We have undertaken a comprehensive functional characterization of protein variants of MRP4 found in Caucasians and other ethnicities. A total of 11 MRP4 missense genetic variants (nonsynonymous SNPs), fused to green fluorescent protein (GFP), were examined in Xenopus laevis oocytes for their effect on expression, localization, and function of the transporter. Radiolabeled 6-MP and PMEA were chosen…

Mboat7 down-regulation by hyper-insulinemia induces fat accumulation in hepatocytes.

2020

Background: Naturally occurring variation in Membrane-bound O-acyltransferase domain-containing 7 (MBOAT7), encoding for an enzyme involved in phosphatidylinositol acyl-chain remodelling, has been associated with fatty liver and hepatic disorders. Here, we examined the relationship between hepatic Mboat7 down-regulation and fat accumulation. Methods: Hepatic MBOAT7 expression was surveyed in 119 obese individuals and in experimental models. MBOAT7 was acutely silenced by antisense oligonucleotides in C57Bl/6 mice, and by CRISPR/Cas9 in HepG2 hepatocytes. Findings: In obese individuals, hepatic MBOAT7 mRNA decreased from normal liver to steatohepatitis, independently of diabetes, inflammatio…

The four murine peroxisomal ABC-transporter genes differ in constitutive, inducible and developmental expression.

1999

Four ATP-binding cassette (ABC) half-transporters have been identified in mammalian peroxisomes: adrenoleukodystrophy protein (ALDP), adrenoleukodystrophy-related protein (ALDRP), 70-kDa peroxisomal membrane protein (PMP70) and PMP70-related protein (P70R). Inherited defects in ALDP cause the neurodegenerative disorder X-linked adrenoleukodystrophy (X-ALD). By comparative Northern blot analyses we found each of the four murine peroxisomal ABC transporter mRNA species at maximum abundance only in a few tissues, which differed for each family member. The four genes were also regulated differentially during mouse brain development: ALDP mRNA was most abundant in embryonic brain and gradually d…

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2020

Bakalaura darba “Tiešsaistes viesnīcu un atpūtas piedāvājumu portālu digitālā mārketinga komunikācijas analīze” mērķis ir izpētīt, kādus digitālā mārketinga kanālus izmanto tiešsaistes viesnīcu un atpūtas piedāvājumu portāli “GribuAtpusties.lv” un “HotHotPack.com” un, kādi ir ceļotāju paradumi, izvēloties atpūtas piedāvājumus Baltijas valstīs. Darbs sastāv no trīs daļām: teorētiskās daļas, kur ir apkopota informācija par zīmola atpazīstamību, digitālā mārketinga komunikāciju un tūrisma mārketingu, metodoloģijas, kur ir paskaidrotas pētnieciskās metodes – kvantitatīvā un kvalitatīvā kontentanalīze, aptauja un intervija, kā arī empīriskās daļas, kur ir veikta iegūto datu analīze un izvirzīti …

Synthesis, computational docking and biological evaluation of celastrol derivatives as dual inhibitors of SERCA and P-glycoprotein in cancer therapy.

2021

Abstract A series of eleven celastrol derivatives was designed, synthesized, and evaluated for their in vitro cytotoxic activities against six human cancer cell lines (A549, HepG2, HepAD38, PC3, DLD-1 Bax-Bak WT and DKO) and three human normal cells (LO2, BEAS-2B, CCD19Lu). To our knowledge, six derivatives were the first example of dipeptide celastrol derivatives. Among them, compound 3 was the most promising derivative, as it exhibited a remarkable anti-proliferative activity and improved selectivity in liver cancer HepAD38 versus human normal hepatocytes, LO2. Compound 6 showed higher selectivity in liver cancer cells against human normal lung fibroblasts, CCD19Lu cell line. The Ca2+ mob…

Potassium uptake system Trk2 is crucial for yeast cell viability during anhydrobiosis

2013

Yeasts grow at very different potassium concentrations, adapting their intracellular cation levels to changes in the external environment. Potassium homeostasis is maintained with the help of several transporters mediating the uptake and efflux of potassium with various affinities and mechanisms. In the model yeast Saccharomyces cerevisiae, two uptake systems, Trk1 and Trk2, are responsible for the accumulation of a relatively high intracellular potassium content (200-300 mM) and the efflux of surplus potassium is mediated by the Tok1 channel and active exporters Ena ATPase and Nha1 cation/proton antiporter. Using a series of deletion mutants, we studied the role of individual potassium tra…

A study on 3‐deoxy‐D‐arabino‐heptulosonic Acid 7‐Phospate Synthase in Higher Plants. The existence of three isoenzymes in Pisum sativum

1976

Purification and partial amino acid sequences of the enzyme vinorine synthase involved in a crucial step of ajmaline biosynthesis.

2004

The acetyl-CoA-dependent enzyme vinorine synthase was isolated from hybrid cell suspension cultures of Rauvolfia serpentina and Rhazya stricta. The sarpagan-type alkaloid gardneral was used as a substrate of the enzyme leading to the ajmalan-type 10-methoxyvinorine. An HPLC-based assay was developed to monitor vinorine synthase activity, which allowed establishing a five step purification procedure combining anion exchange, hydrophobic interaction, hydroxyapatite and gel filtration. Purification resulted in a yield of 0.2% and an approximately 991-fold enrichment of the acetyltransfer activity. SDS-PAGE analysis showed a Mr for the enzyme of approximately 50 kDa. The four peptide fragments …