Biomaterial Database

Spectroscopic studies of pyridoxamine (pyridoxine) 5'-phosphate oxidase. Equilibrium dissociation constants and spectra for riboflavin 5'-phosphate and analogues. 1979

A H Merrill, and S Kasai, and K Matsui, and H Tsuge, and D B McCormick

Pyridoxamine (pyridoxine) 5'-phosphate oxidase (EC 1.4.3.5) has been shown to bind 1 mol of riboflavin 5'-phosphate (FMN) per mol of apoenzyme and is active with or inhibited by numerous FMN analogues [Kazarinoff, M. N., & McCormick, D. B. (1975) J. Biol. Chem. 250, 3436--3442]. The KD values and spectra for selected apoenzyme--flavin complexes have been determined and used to elucidate some of the properties of the FMN-binding site of this flavoprotein. Alterations of the pyrimidinoid portion of the flavin ring decrease binding considerably. The absorption spectra for the protein complexes with 3-deaza-FMN and 8-hydroxy-FMN indicate the presence of a dipolar or positively charged protein group near N1 and O2. The substitution of methyl for hydrogen at N3 apparently causes distortion of the interaction between the flavin ring and an active-site aromatic amino acid residue. Although binding is also decreased somewhat by substitutions at postions 8 and 8 alpha, considerable bulk [e.g., 8-(diethylamino)-FMN and 8 alpha-S-(N-acetyl-cysteinyl)-FMN] is accommodated. Hence, this portion of the flavin ring is probably oriented toward, possibly in contact with, solvent, as has been found for the flavodoxins. The importance of optimum interactions between the flavin and the apoprotein is further emphasized by large differences in the activity of flavin analogues that have similar midpoint potentials in solution.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D011734	Pyridoxaminephosphate Oxidase	An enzyme catalyzing the deamination of pyridoxaminephosphate to pyridoxal phosphate. It is a flavoprotein that also oxidizes pyridoxine-5-phosphate and pyridoxine. EC 1.4.3.5.	Pyridoxinephosphate Oxidase,Pyridoxine-5-Phosphate Oxidase,Oxidase, Pyridoxaminephosphate,Oxidase, Pyridoxine-5-Phosphate,Oxidase, Pyridoxinephosphate,Pyridoxine 5 Phosphate Oxidase
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D005486	Flavin Mononucleotide	A coenzyme for a number of oxidative enzymes including NADH DEHYDROGENASE. It is the principal form in which RIBOFLAVIN is found in cells and tissues.	FMN,Flavin Mononucleotide Disodium Salt,Flavin Mononucleotide Monosodium Salt,Flavin Mononucleotide Monosodium Salt, Dihydrate,Flavin Mononucleotide Sodium Salt,Riboflavin 5'-Monophosphate,Riboflavin 5'-Phosphate,Riboflavin Mononucleotide,Sodium Riboflavin Phosphate,5'-Monophosphate, Riboflavin,5'-Phosphate, Riboflavin,Mononucleotide, Flavin,Mononucleotide, Riboflavin,Phosphate, Sodium Riboflavin,Riboflavin 5' Monophosphate,Riboflavin 5' Phosphate,Riboflavin Phosphate, Sodium
D000587	Oxidoreductases Acting on CH-NH Group Donors	Enzymes catalyzing the dehydrogenation of secondary amines, introducing a C	Secondary Amine Oxidoreductases,Amine Oxidoreductases, Secondary Amine,Amine Oxidoreductases, Secondary,Oxidoreductases Acting on CH NH Group Donors,Oxidoreductases, Secondary Amine
D001051	Apoenzymes	The protein components of enzyme complexes (HOLOENZYMES). An apoenzyme is the holoenzyme minus any cofactors (ENZYME COFACTORS) or prosthetic groups required for the enzymatic function.	Apoenzyme
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.