Biomaterial Database

The temperature and pH dependence of some properties of p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens. 1989

W J Van Berkel, and F Müller

Department of Biochemistry, Agricultural University, Wageningen, The Netherlands.

The free and complexed flavoprotein, p-hydroxybenzoate hydroxylase, was studied by light-absorption, circular-dichroism and fluorescence techniques as a function of the pH. The following compounds served as ligands for the enzyme: p-hydroxybenzoate, p-fluorobenzoate, benzoate, p-aminobenzoate and tetrafluoro-p-hydroxybenzoate. Depending on the technique used, the various ligands exhibit pH-dependent physical properties and dissociation constants. The data can be fitted with pKa values in the range 7.7-7.9. It is suggested that this pKa value belongs to a tyrosine residue in the active center of the enzyme. This assignment is supported by published data and additional experiments.

UI	MeSH Term	Description	Entries
D011551	Pseudomonas fluorescens	A species of nonpathogenic fluorescent bacteria found in feces, sewage, soil, and water, and which liquefy gelatin.	Bacillus fluorescens,Bacillus fluorescens liquefaciens,Bacterium fluorescens,Liquidomonas fluorescens
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
D004795	Enzyme Stability	The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.	Enzyme Stabilities,Stabilities, Enzyme,Stability, Enzyme
D005453	Fluorescence	The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D006899	Mixed Function Oxygenases	Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.	Hydroxylase,Hydroxylases,Mixed Function Oxidase,Mixed Function Oxygenase,Monooxygenase,Monooxygenases,Mixed Function Oxidases,Function Oxidase, Mixed,Function Oxygenase, Mixed,Oxidase, Mixed Function,Oxidases, Mixed Function,Oxygenase, Mixed Function,Oxygenases, Mixed Function
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D015109	4-Hydroxybenzoate-3-Monooxygenase	A flavoprotein that catalyzes the synthesis of protocatechuic acid from 4-hydroxybenzoate in the presence of molecular oxygen. EC 1.14.13.2.	p-Hydroxybenzoate Hydroxylase,para-Hydroxybenzoate Hydroxylase,4 Hydroxybenzoate 3 Monooxygenase,Hydroxylase, p-Hydroxybenzoate,Hydroxylase, para-Hydroxybenzoate,p Hydroxybenzoate Hydroxylase,para Hydroxybenzoate Hydroxylase