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Molecular Aspects of the Activity and Inhibition of the FAD-Containing Monoamine Oxidases
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
FAD, a redox cofactor important for catalysis in many enzymes, is derived from the vitamin riboflavin. As in most FAD-containing enzymes, the adenine part of the molecule binds to a Rossman fold in the protein. The isoalloxazine ring part of FAD is held in position by a covalently bond to a cysteine residue in MAO (Fig. 10.3). In all crystal structures of MAO B, the isoalloxazine ring is bent by about 30° (Binda et al., 2003) with about 0.3° difference between the oxidized and reduced forms. However, molecular dynamics has now enabled a more realistic picture of the shape of the flavin in the flexible protein active site. Two different studies have shown that it is almost planar in the oxidized form (FAD) (Vianello et al., 2012; Zapata-Torres et al., 2015), but when it is reduced either by a hydride ion from the substrate transferred to N5 in the first step of the catalytic mechanism or after the propargylamine adduct has formed at N5, the FADH2 is bent by almost 30 degrees (Borstnar et al., 2011) in agreement with the crystal structure.
Application of Nonlinear Microscopy in Life Sciences
Published in Lingyan Shi, Robert R. Alfano, Deep Imaging in Tissue and Biomedical Materials, 2017
Zdenek Svindrych, Ammasi Periasamy
Flavins, fluorescent molecules derived from riboflavin, are important sources of autofluorescence in the green spectral range. Biologically most important are flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). These are cofactors of many enzymatic reactions, often connected to cellular metabolism (FMN takes part in the electron transport chain, FAD is involved in citric acid cycle and in oxidative phosphorylation). FAD, together with NADH, was used as a basis for calculating redox ratio [123] to enhance the sensitivity with which precancerous cells can be discriminated. The fluorescence lifetime of FAD is also strongly dependent on its binding state, but unlike that of NADH, the lifetime of bound FAD is much shorter than that of the free molecule [19].
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
FAD (flavin adenine dinucleotide) is a co-enzyme important in various biochemical reactions. It comprises of phosphorylated vitamin B2 (riboflavin) molecule linked to the nucleotide adenine monophosphate (AMP).
Polarised fluorescence in FAD excited at 355 and 450 nm in water–propylene glycol solutions
Published in Molecular Physics, 2022
D. M. Beltukova, M. K. Danilova, I. A. Gradusov, V. P. Belik, I. V. Semenova, O. S. Vasyutinskii
The investigation of intracellular processes using time-resolved spectroscopy of endogenous fluorophores is currently one of the mainstreams in biological research. Nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are important endogenous fluorophores that play an essential role in cellular respiration and are widely used as fluorescent biomarkers for investigation of metabolic processes in cells and tissues (see, e.g. review papers [1–3] and references therein). FAD is one of the most important cofactors that catalyses a number of one- and two-electron redox reactions as a component of flavoproteins and acts as a photoreceptor pigment. A wide variety of cellular processes utilise FAD: bioenergetics and metabolism, reactive oxygen species (ROS) production and defense against oxidative stress, cell differentiation, etc. In particular, disorders in FAD metabolism can lead to deficiencies of corresponding flavoproteins and cause a number of pathologies [4].