Biomaterial Database

Purification of porphobilinogen deaminase from Euglena gracilis and studies of its kinetics. 1981

D C Williams, and G S Morgan, and E McDonald, and A R Battersby

1. Porphobilinogen deaminase [porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8] from Euglena gracilis was purified more than 200-fold. 2. The enzyme has a molecular weight of 41 000 +/- 2000, does not contain a chromophoric prosthetic group, and appears not to require metal ions for activity. 3. The stoicheiometry of the overall reaction at pH 7.4 was shown to be: 4 Porphobilinogen leads to uroporphyrinogen-I + 4 NH4+. This stoicheiometry for porphobilinogen and uroporphyrinogen was also observed over a wide range of pH values. 4. Initial-velocity studies showed a hyperbolic dependence of velocity on substrate concentration, demonstrating the existence of a displacement-type mechanism. 5. Vmax. varied with pH as a typical bell-shaped curve, indicating that two ionizable groups with pK values of 6.1 and 8.9 are important for catalysis. A plot of Vmax./Km against pH showed a single ionization (pK 8.2) to influence binding of substrate.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D011162	Porphobilinogen
D011163	Hydroxymethylbilane Synthase	An enzyme that catalyzes the tetrapolymerization of the monopyrrole PORPHOBILINOGEN into the hydroxymethylbilane preuroporphyrinogen (UROPORPHYRINOGENS) in several discrete steps. It is the third enzyme in the 8-enzyme biosynthetic pathway of HEME. In humans, deficiency in this enzyme encoded by HMBS (or PBGD) gene results in a form of neurological porphyria (PORPHYRIA, ACUTE INTERMITTENT). This enzyme was formerly listed as EC 4.3.1.8	Porphobilinogen Ammonia-Lyase,Porphobilinogen Deaminase,Uroporphyrinogen I Synthase,Hydroxymethylbilane Synthetase,Pre-uroporphyrinogen Synthetase,Preuroporphyrinogen Synthetase,Ammonia-Lyase, Porphobilinogen,Deaminase, Porphobilinogen,Porphobilinogen Ammonia Lyase,Pre uroporphyrinogen Synthetase,Synthase, Hydroxymethylbilane,Synthase, Uroporphyrinogen I,Synthetase, Hydroxymethylbilane,Synthetase, Pre-uroporphyrinogen,Synthetase, Preuroporphyrinogen
D002848	Chromatography, DEAE-Cellulose	A type of ion exchange chromatography using diethylaminoethyl cellulose (DEAE-CELLULOSE) as a positively charged resin. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	DEAE-Cellulose Chromatography,Chromatography, DEAE Cellulose,DEAE Cellulose Chromatography
D005056	Euglena gracilis	A species of fresh-water, flagellated EUKARYOTES in the phylum EUGLENIDA.	Euglena gracili,gracilis, Euglena
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
D000642	Ammonia-Lyases	Enzymes that catalyze the formation of a carbon-carbon double bond by the elimination of AMMONIA. EC 4.3.1.	Ammonia Lyase,Ammonia-Lyase,Ammonia Lyases,Lyase, Ammonia
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