Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Prostatic-Group-Label Immunoassay (PGLIA) technique has been incorporated into a reagent-strip format. We report use of flavin N6-(N'-2,4-dinitrophenyl-6-aminohexyl)adenine dinucleotide (DNP-FAD) as the prosthetic group derivative and 6-N-(2,4-dinitrophenyl)aminohexanoic acid (DNP-caproate) as the competing ligand. DNP-FAD not bound by antibody combines with glucose oxidase apoenzyme, which then reacts with glucose and oxygen, and gives color through a peroxidase-linked system. The rate of color generation is thus a function of the DNP-caproate concentration. PGLIA reagent strips are prepared by sequential impregnations of filter paper with an acetone solution of indicator (3,3',5,5'-tetramethylbenzidine); an aqueous solution containing glucose oxidase apoenzyme, the rest of the color generation system, stabilizers, and antibody to DNP; and a solution of DNP-FAD in n-propanol. This preparation permits effective antibody binding, and prevents premature interaction of immunoassay components. A quantitative color response to concentrations of DNP-caproate in the range of 1 to 8 mumol/L was demonstrated with these reagent strips. Prototype PGLIA reagent strips for theophylline and phenytoin have been successfully developed by substituting the appropriate FAD derivative and antibody for the corresponding reagents in the DNP model system.
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PMID:Adaptation of Prostatic-Group-Label Homogeneous Immunoassay to reagent-strip format. 726 29

The resonance coherent anti-Stokes Raman technique was used to obtain vibrational spectra of flavin in flavodoxins from Desulfovibrio gigas and Desulfovibrio vulgaris and of the simpler 6,7-dimethyl-8-ribityllumazine chromophore in the blue fluorescence lumazine protein from the bioluminescent bacterium Photobacterium phosphoreum. In the region examined, 1100-1700 cm-1, the Raman spectrum of the lumazine is less crowded than that of the flavin and this facilitates assignment of observed frequencies to particular vibrational modes. Certain modes are not affected by chromophore binding to the protein, but others are changed in frequency or intensity in a way that can be rationalized by expected interactions of the chromophore with the amino acid residues of the binding site. For example, a tentative assignment of change in hydrogen bonding at N(5) is suggested as the cause of the frequency shift for the chromophore in both flavodoxins (free-bound, 1582-1572 cm-1) and for C(4)=O in glucose oxidase (1359-1364 cm-1) and lumazine protein (1359-1362 cm-1). Shifts of the C(2)-N(3) mode in D2O may arise from hydrogen-bonding changes at C(2)=O in lumazine protein (1284-1291 cm-1), flavodoxin (1300-1280 cm-1), and glucose oxidase (1297-1287 cm-1). Bonding at N(3)-H may be the origin of changes in the frequency or intensity of the amide III mode in riboflavin binding protein and glucose oxidase. A stacking interaction is suggested for the change in a pyrimidine ring mode in FAD (1508 cm-1) since this mode is found at 1504 cm-1 in 30% Me2SO/H2O, where the adenine and pyrimidine are unstacked. The results clearly indicate different interactions in the binding sites of those proteins studied to date.
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PMID:Protein-ligand interactions in lumazine protein and in Desulfovibrio flavodoxins from resonance coherent anti-Stokes Raman spectra. 742 21

We have isolated the gene encoding 2-nitropropane dioxygenase from Hansenula mrakii, an FAD enzyme that catalyzes the oxygenative denitrification of various anionic nitroalkanes. The gene contained an open reading frame consisting of 1122 nucleotides corresponding to 374 amino acid residues. The protein molecular mass was estimated to be 41,466 Da, which was similar to the subunit molecular mass of the enzyme determined by SDS/PAGE. Several FAD enzymes such as D-amino acid oxidase and glucose oxidase also catalyze the oxidation of nitroalkanes as a side-reaction, although not so efficiently [Kido, T. & Soda, K. (1984) Arch. Biochem. Biophys. 234, 468-475]. However, we found no proteins in the databases (GenBank, EMBL, PIR and SWISS-PROT) which are homologous to 2-nitropropane dioxygenase of H. mrakii in primary structure. No protein motifs, including a nucleotide-binding motif, GXGXXG, were found in PROSITE, a database of biologically significant protein sites and patterns. Accordingly, 2-nitropropane dioxygenase is a new type of flavoprotein with a unique structure.
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PMID:Unique primary structure of 2-nitropropane dioxygenase from Hansenula mrakii. 781 73

A thermodynamic investigation was carried out on heat-induced flavin dissociation in Aspergillus niger glucose oxidase. Experimental measurements performed by difference spectroscopy showed that the dissociation of the FAD cofactors is a highly cooperative process and is probably related to the extended conformational changes resulting from protein unfolding. Microenvironmental modifications attained by the addition of polyhydric compounds (glycerol, fructose, sucrose and sorbitol) from 10 to 30% by weight were found to hinder the dissociation. The stabilizing effect provided by these substances was interpreted as a consequence of preferential exclusion phenomena, which are likely to be determined by the perturbation of the surface tension of water, in the case of sugars, or by the solvophobic effect, in the case of glycerol.
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PMID:Effect of polyols and sugars on heat-induced flavin dissociation in glucose oxidase. 786 96

Cholesterol oxidase from Brevibacterium sterolicum is a flavin-dependent enzyme that catalyzes the oxidation and isomerization of 3 beta-hydroxy steroids with a double bond at delta 5-delta 6 of the steroid ring backbone. The crystal structure of the free enzyme in the absence of a steroid substrate has previously been determined. In this paper we report the crystal structure of the complex of cholesterol oxidase with the steroid substrate dehydroisoandrosterone, refined at 1.8-A resolution. The final crystallographic R-value is 15.7% for all reflections between 10.0- and 1.8-A resolution. The steroid is buried within the protein in an internal cavity which, in the free enzyme crystal structure, was occupied by a lattice of water molecules. The conformations of a number of side chains lining the active-site cavity have changed in order to accommodate the steroid substrate. A loop region of the structure between residues 70 and 90 differs significantly between the substrate-free and substrate-bound forms of the enzyme, presumably to facilitate binding of the steroid. The hydroxyl group of the steroid substrate is hydrogen-bonded to both the flavin ring system of the FAD cofactor and a bound water molecule. FAD-dependent cholesterol oxidase shares significant structural homology with another flavoenzyme, glucose oxidase, suggesting that it might also be a member of the glucose-methanol-choline (GMC) oxidoreductase family. Although there is only limited sequence homology, a superposition of these two structures reveals a conserved histidine residue within hydrogen-bonding distance of the active-site water molecule.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Crystal structure of cholesterol oxidase complexed with a steroid substrate: implications for flavin adenine dinucleotide dependent alcohol oxidases. 821 17

Glucose oxidase (beta-D-glucose: oxygen 1-oxidoreductase, EC 1.1.3.4) is an FAD-dependent enzyme that catalyzes the oxidation of beta-D-glucose by molecular oxygen. The crystal structure of the partially deglycosylated enzyme from Aspergillus niger has been determined by isomorphous replacement and refined to 2.3 A resolution. The final crystallographic R-value is 18.1% for reflections between 10.0 and 2.3 A resolution. The refined model includes 580 amino acid residues, the FAD cofactor, six N-acetylglucosamine residues, three mannose residues and 152 solvent molecules. The FAD-binding domain is topologically very similar to other FAD-binding proteins. The substrate-binding domain is formed from non-continuous segments of sequence and is characterized by a deep pocket. One side of this pocket is formed by a six-stranded antiparallel beta-sheet with the flavin ring system of FAD located at the bottom of the pocket on the opposite side. Part of the entrance to the active site pocket is at the interface to the second subunit of the dimeric enzyme and is formed by a 20-residue lid, which in addition covers parts of the FAD-binding site. The carbohydrate moiety attached to Asn89 at the tip of this lid forms a link between the subunits of the dimer.
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PMID:Crystal structure of glucose oxidase from Aspergillus niger refined at 2.3 A resolution. 842 Dec 98

Insulation of the electrical contact between a redox protein and an electrode surface upon association of an antibody to an antigen monolayer assembled on the electrode is used to develop immunosensor devices. In one configuration, a mixed monolayer consisting of the N epsilon-(2,4-dinitrophenyl)lysine antigen and ferrocene units acting as electron transfer mediators is applied to sense the dinitrophenyl antibody (DNP-Ab) in the presence of glucose oxidase (GOx) and glucose. In the absence of DNP-Ab, the mixed monolayer electrode stimulates the mediated electrocatalyzed oxidation of glucose that results in an amplified amperometric response. Association of the DNP-Ab to the modified electrode blocks the electrocatalytic transformation. The extent of the electrode insulation by the DNP-Ab is controlled by the Ab concentration in the sample. In the second configuration, a N epsilon-(2,4-dinitrophenyl)lysine antigen monolayer assembled on a Au electrode is applied to sense the DNP-Ab in the presence of a redox-modified GOx, exhibiting electrical communication with the electrode surface. Two kinds of redox-modified "electrically wired" GOx are applied: GOx modified by N-(ferrocenylmethyl)caproic acid, Fc-GOx, and a novel electrobiocatalyst generated by reconstitution of apo-GOx with a ferrocene-modified FAD semisynthetic cofactor. Electrocatalytic oxidation of glucose by the electrically wired biocatalysts proceeds in the presence of the antigen monolayer electrode, giving rise to an amplified amperometric signal. The electrocatalytic transformation is blocked upon association of the DNP-Ab to the monolayer electrode. The extent of electrode insulation toward the bioelectrocatalytic oxidation of glucose is controlled by the DNP-Ab concentrations in the samples. The application of biocatalysts for amperometric sensing of antigen-antibody interactions at the electrode surface makes the electrode insensitive to microscopic pinhole defects in the monolayer assembly. The antigen monolayer electrode is applied to sense the DNP-Ab in the concentration range 1-50 micrograms mL-1.
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PMID:Application of redox enzymes for probing the antigen-antibody association at monolayer interfaces: development of amperometric immunosensor electrodes. 879 76

The catalytic oxidation of beta-D-glucose by the enzyme glucose oxidase involves a redox change of the flavin coenzyme. The structure and the dynamics of the two extreme glucose oxidase forms were studied by using infrared absorption spectroscopy of the amide I'band, tryptophan fluorescence quenching and hydrogen isotopic exchange. The conversion of FAD to FADH2 does not change the amount of alpha-helix present in the protein outer shell, but reorganizes a fraction of random coil to beta-sheet structure. The dynamics of the protein interior vary with the redox states of the flavin without affecting the motions of the structural elements near the protein surface. From the structure of glucose oxidase given by X-ray crystallography, these results suggest that the dynamics of the interface between the two monomers are involved in the catalytic mechanism.
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PMID:Dynamic and structural properties of glucose oxidase enzyme. 946 87

The complete amino acid sequence of glucose oxidase from Penicillium amagasakiense was determined by Edman degradation and mass spectrometry of peptide fragments derived from three different specific proteolytic digests and a cyanogen bromide cleavage. The complete sequence of each monomer comprises 587 amino acid residues, contains three cysteine residues, and seven potential N-glycosylation sites, of which at least five were confirmed to be glycosylated. Glucose oxidase from P. amagasakiense shows a high degree of identity (66%) and 79% similarity to glucose oxidase from Aspergillus niger, and is a member of the glucose-methanol-choline (GMC) oxidoreductase family. The tertiary structures of glucose oxidase from A. niger and cholesterol oxidase from Brevibacterium sterolicum were superimposed to provide a template for the sequence comparison of members of the GMC family. The general topology of the GMC oxidoreductases is conserved, with the exception of the presence of an active site lid in cholesterol oxidase and the insertion of additional structural elements in the substrate-binding domain of alcohol oxidase. The overall structure can be divided into five distinct sequence regions: FAD-binding domain, extended FAD-binding domain, flavin attachment loop and intermediate region, FAD covering lid, and substrate-binding domain. The FAD-binding and the extended FAD-binding domains are composed of several separate sequence regions. The other three regions each comprise a single contiguous sequence. Four major consensus patterns have been identified, including the nucleotide-binding consensus sequence close to their N-termini. The functions of the two motifs recently selected by the Genetics Computer Group, Madison, Wisconsin, as additional signature patterns of the GMC oxidoreductases are discussed. The other consensus patterns belong to either the FAD-binding or the extended FAD-binding domain. In addition, the roles of conserved residues are discussed wherever possible.
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PMID:Glucose oxidase from Penicillium amagasakiense. Primary structure and comparison with other glucose-methanol-choline (GMC) oxidoreductases. 952 16

p-Hydroxybenzoate hydroxylase, D-amino acid oxidase, cholesterol oxidase and glucose oxidase form a family of structurally related flavoenzymes. Comparison of their three-dimensional structures reveal how the same FAD-binding scaffold has been employed to implement diverse active-site architectures, suited for different types of catalytic reactions. The substrate binding mode differs in each of these enzymes, with the catalytically relevant residues not located on homologous positions. A common feature is provided by the ability of these enzyme to bury their substrates beneath the protein surface. In D-amino acid oxidase and cholesterol oxidase, a loop forms a 'lid' controlling the active site accessibility, whereas in p-hydroxybenzoate hydroxylase is the flavin itself, which swings out to allow substrate binding. The crystallographic analysis has revealed that the GTP-dissociation inhibitor of RAB GTPases has a folding topology remarkably similar to p-hydroxybenzoate hydroxylase. This finding highlights the versatile nature of this folding topology, which in addition to flavin-dependent catalysis, is suited for diverse functions, such as the regulation of GTPases.
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PMID:The PHBH fold: not only flavoenzymes. 954 98


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