Search results for "cofactor"
showing 10 items of 74 documents
Human D-Amino Acid Oxidase: Structure, Function, and Regulation
2018
D-Amino acid oxidase (DAAO) is an FAD-containing flavoenzyme that catalyzes with absolute stereoselectivity the oxidative deamination of all natural D-amino acids, the only exception being the acidic ones. This flavoenzyme plays different roles during evolution and in different tissues in humans. Its three-dimensional structure is well conserved during evolution: minute changes are responsible for the functional differences between enzymes from microorganism sources and those from humans. In recent years several investigations focused on human DAAO, mainly because of its role in degrading the neuromodulator D-serine in the central nervous system. D-Serine is the main coagonist of N-methyl D…
Control of the bifunctional O 2 ‐sensor kinase NreB of Staphylococcus carnosus by the nitrate sensor NreA: Switching from kinase to phosphatase state
2019
The NreB-NreC two-component system of Staphylococcus carnosus for O2 sensing cooperates with the accessory nitrate sensor NreA in the NreA-NreB-NreC system for coordinated sensing and regulation of nitrate respiration by O2 and nitrate. ApoNreA (NreA in the absence of nitrate) interacts with NreB and inhibits NreB autophosphorylation (and activation). NreB contains the phosphatase motif DxxxQ. The present study shows that NreB on its own was inactive for the dephosphorylation of the phosphorylated response regulator NreC (NreC-P), but co-incubation with NreB and NreA stimulated NreC-P dephosphorylation. Either the presence of NreA · NO 3 - instead of apoNreA or mutation of the phosphatase m…
Aurophilicity as a cofactor in crystal engineering. Dicyanoaurate(I) anion as a building block in a novel Co(II)–Au(I) bimetallic assembly
2002
A 2D grid-shaped cyanide-bridged Co(II)–Au(I) bimetallic coordination polymer, [Co(DMF)2{Au(CN)2}2], has been prepared from the [Au(CN)2]2 building block; sheets associate pair-wise by aurophilic interactions and the compound exhibits zeolite-like properties. Lloret Pastor, Francisco, Francisco.Lloret@uv.es
Melatonin activates the peroxidase-oxidase reaction and promotes oscillations.
2001
We have studied the peroxidase-oxidase reaction with NADH and O2 as substrates and melatonin as a cofactor in a semibatch reactor. We show for the first time that melatonin is an activator of the reaction catalyzed by enzymes from both plant and animal sources. Furthermore, melatonin promotes oscillatory dynamics in the pH range from 5 to 6. The frequency of the oscillations depends on the pH such that an increase in pH was accompanied by a decrease in frequency. Conversely, an increase in the flow rate of NADH or an increase in the average concentration of NADH resulted in an increase in oscillation frequency. Complex dynamics were not observed with melatonin as a cofactor. These results a…
Targeting MYCN in Pediatric and Adult Cancers
2021
The deregulation of theMYCfamily of oncogenes, includingc-MYC,MYCNandMYCLoccurs in many types of cancers, and is frequently associated with a poor prognosis. The majority of functional studies have focused onc-MYCdue to its broad expression profile in human cancers. The existence of highly conserved functional domains betweenMYCNandc-MYCsuggests thatMYCNparticipates in similar activities.MYCencodes a basic helix-loop-helix-leucine zipper (bHLH-LZ) transcription factor (TF) whose central oncogenic role in many human cancers makes it a highly desirable therapeutic target. Historically, as a TF, MYC has been regarded as “undruggable”. Thus, recent efforts focus on investigating methods to indi…
Expression and regulation by interferon-γ of the membrane-bound complement regulators CD46 (MCP), CD55 (DAF) and CD59 in gastrointestinal tumours
1999
The membrane-bound complement inhibitors CD46 (membrane cofactor protein), CD55 (decay-accelerating factor) and CD59 (protectin) protect tumour cells against lysis by activated complement. In this study, a total of 14 (3 gastric, 3 colonic and 8 pancreatic) gastrointestinal tumour cell lines were examined for the expression of CD46, CD55 and CD59 with respect to the regulatory efficacy of interferon-gamma (IFN-gamma). The effects of IFN-gamma on mRNA and protein expression levels of CD46, CD55 and CD59 were evaluated by Northern blot hybridisation, RT-PCR, flow cytometry and immunostaining. In unstimulated cell lines, CD46 and CD59 transcripts were expressed at comparable levels, whereas th…
Efficacy and safety of cyclic pyranopterin monophosphate substitution in severe molybdenum cofactor deficiency type A: a prospective cohort study.
2015
Summary Background Molybdenum cofactor deficiency (MoCD) is characterised by early, rapidly progressive postnatal encephalopathy and intractable seizures, leading to severe disability and early death. Previous treatment attempts have been unsuccessful. After a pioneering single treatment we now report the outcome of the complete first cohort of patients receiving substitution treatment with cyclic pyranopterin monophosphate (cPMP), a biosynthetic precursor of the cofactor. Methods In this observational prospective cohort study, newborn babies with clinical and biochemical evidence of MoCD were admitted to a compassionate-use programme at the request of their treating physicians. Intravenous…
The primary structural photoresponse of phytochrome proteins captured by a femtosecond X-ray laser
2019
Phytochrome proteins control the growth, reproduction, and photosynthesis of plants, fungi, and bacteria. Light is detected by a bilin cofactor, but it remains elusive how this leads to activation of the protein through structural changes. We present serial femtosecond X-ray crystallographic data of the chromophore-binding domains of a bacterial phytochrome at delay times of 1 ps and 10 ps after photoexcitation. The data reveal a twist of the D-ring, which leads to partial detachment of the chromophore from the protein. Unexpectedly, the conserved so-called pyrrole water is photodissociated from the chromophore, concomitant with movement of the A-ring and a key signaling aspartate. The chan…
Endoribonuclease IV. A poly(A)-specific ribonuclease from chick oviduct. 1. Purification of the enzyme.
1976
A new endoribonuclease, termed endoribonuclease IV, has been described. This enzyme has been isolated from chick oviducts and purified 15 000-fold in a 25% yield nearly to homogeneity. The nuclease, which specifically degrades poly(A), forms oligonucleotides of an average chain length of 10. These (A)-10 fragments are terminated by 3'-hydroxyl and 5'-phosphate groups. The enzyme has a pH optimum at 8.7, requires Mn2+ or Mg2+ as a cofactor, and has a molecular weight of about 45 000.
[26] Isoforms of nitric-oxide synthase: Purification and regulation
1994
Publisher Summary Nitric-oxide synthase (NOS) catalyzes the five-electron oxidation of L-arginine to the nitric oxide radical (.NO) and L-citrulline. Molecular oxygen is the cosubstrate of the enzyme. NO synthase activity has been found in a large variety of cells and tissues. The enzyme exists in several isoforms, three of which have been purified, characterized, and cloned. The activities of all three isoforms are found distributed between the soluble and particulate fractions of cells. Isoform I (from brain) and isoform II (from cytokine-induced macrophages) are mostly soluble proteins. Isoform III from endothelial cells is myristoylated and found predominantly in the particulate fractio…