infrastruktura: Flavin adenine dinucleotide

Evidence: 100 • authority: 72

In biochemistry, flavin adenine dinucleotide (FAD) is a redox-active coenzyme associated with various proteins, which is involved with several enzymatic reactions in metabolism. A flavoprotein is a protein that contains a flavin group, which may be in the form of FAD or flavin mononucleotide (FMN). Many flavoproteins are known: components of the succinate dehydrogenase complex, α-ketoglutarate dehydrogenase, and a component of the pyruvate dehydrogenase complex. FAD exists in two common oxidation states, the fully oxidized form (FAD) and the fully reduced, dihydrogenated form, FADH2. Other oxidation states also exist, including the N-oxide and semiquinone states. FAD, in its fully oxidized…

Evidence: 45 • authority: 92

Direct coupling of lactate oxidation with butyryl-CoA formation via a canonical electron transfer flavoprotein in Fusobacterium nucleatum.. The gram-negative opportunistic pathogen Fusobacterium nucleatum encodes an electron transfer flavoprotein (ETF) within a 6-gene cluster that also includes genes for a D-lactate dehydrogenase (Ldh), butyryl-CoA dehydrogenase (Bcd), and LrgAB. Herein, we demonstrate that ETF functions as a canonical ETF, transferring two electrons from Ldh following oxidation of D-lactate to Bcd for the reduction of crotonyl-CoA to butyryl-CoA. Steady-state kinetic analysis of the Ldh FN /ETF FN /Bcd FN reaction (lactate + crotonyl-CoA → pyruvate + butyryl-CoA) yielded a…

Evidence: 36 • authority: 92

Insight into the high-potential branch of the alternate NAD<sup>+</sup>-dependent NADPH:ferredoxin oxidoreductase II (NfnII) from Pyrococcus furiosus: evidence for the gating step in electron bifurcation.. We have investigated the rapid-reaction kinetics of the NAD+-dependent NADPH:ferredoxin oxidoreductase II (NfnII) from Pyrococcus furiosus, permitting comparison with work done with the paralog NAD+-dependent NADPH:ferredoxin oxidoreductase (NfnI). The half-potentials of the electron-bifurcating L-FAD are highly crossed in NfnI, meaning that the potential for the quinone/semiquinone couple is significantly lower than that for the semiquinone/hydroquinone, so that the semiquino…

Evidence: 36 • authority: 92

Kinetic mechanisms of electron bifurcation with electron transfer flavoprotein, NADH, butyryl-CoA dehydrogenase, and ferredoxin reveal a semiquinone cycle.. Electron transfer flavoprotein (EtfAB, with α-FAD and β-FAD) and tetrameric butyryl-CoA dehydrogenase (Bcd, with δ-FAD in each subunit) from Acidaminococcus fermentans catalyze electron bifurcation which reduces low potential ferredoxin (Fd) and high potential crotonyl-CoA using NADH as an electron donor. Our previous rapid kinetic studies have demonstrated "pseudo-electron bifurcation" where NADH and two EtfAB molecules generate EtfA SQ B (A SQ contains α-FAD •- ) and the charge-transfer complex of EtfA SQ B HQ :NAD + (B HQ contains β-…

Evidence: — • authority: 92

Covalent Irreversible Inhibitors of Tetracycline Destructases.. Next-generation tetracycline antibiotics are threatened by an emerging resistance mechanism ─ enzymatic inactivation. The relevant enzymes ─ tetracycline destructases (TDases) ─ are structural homologues of class A flavin monooxygenase (FMO) that oxidize tetracycline antibiotics, leading to various inactive degradation products. Small molecule inhibitors of antibiotic-inactivating enzymes are critical clinical therapeutics used to manage bacterial resistance with combination therapy. While reversible TDase inhibitors have been reported, we sought to develop covalent inhibitors that are better aligned with clinically effective c…

Evidence: — • authority: 92

Electrochemical Observation and pH Dependence of All Three Expected Redox Couples in an Extremophilic Bifurcating Electron Transfer Flavoprotein with Fused Subunits.. Bifurcating enzymes employ energy from a favorable electron transfer to drive unfavorable transfer of a second electron, thereby generating a more reactive product. They are therefore highly desirable in catalytic systems, for example, to drive challenging reactions such as nitrogen fixation. While most bifurcating enzymes contain air-sensitive metal centers, bifurcating electron transfer flavoproteins (bETFs) employ flavins. However, they have not been successfully deployed on electrodes. Herein, we demonstrate immobilization…

Evidence: — • authority: 92

An extra residue in the electron transfer chain holds the key for the dual functions of an animal-like cryptochrome.. Homologous cryptochromes and photolyases have evolved divergently, with cryptochromes acting as photoreceptors to regulate circadian rhythms and photolyases serving as DNA repair enzymes. However, a group of these proteins from algae and fungi exhibit dual functions, including the animal-like cryptochrome from Chlamydomonas reinhardtii (CraCRY). In this study, we investigated the mechanism underlying the bifunctionality of CraCRY, using steady-state absorption kinetics, limited proteolysis, and mutagenesis, focusing on the roles of residues in the electron transfer chain bey…