Citation

Jones RM, Jordan PM. Biochem. J. 1994; 299 ( Pt 3)(Pt 3): 895-902.

Copyright

(Copyright © 1994, The Biochemical Society, Publisher Portland Press)

DOI

10.1042/bj2990895

PMID

8192681

PMCID

PMC1138105

Abstract

Porphobilinogen deaminase (EC 4.3.1.8) has been purified to homogeneity (16,000-fold) from the plant Arabidopsis thaliana in yields of 8%. The deaminase is a monomer of M(r) 35,000, as shown by SDS/PAGE, and 31,000, using gel-filtration chromatography. The pure enzyme has a Vmax. of 4.5 mumol/h per mg and a Km of 17 +/- 4 microM. Determination of the pI and pH optimum revealed values of 5.2 and 8.0 respectively. The sequence of the N-terminus was found to be NH2-XVAVEQKTRTAI. The deaminase is heat-stable up to 70 degrees C and is inhibited by NH3 and hydroxylamine. The enzyme is inactivated by arginine-, histidine- and lysine-specific reagents. Incubation with the substrate analogue and suicide inhibitor, 2-bromoporphobilinogen, results in chain termination and in inactivation.

Language: en

Keywords

Amino Acid Sequence; Ammonia; Arabidopsis; Chromatography, Gel; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Hot Temperature; Hydrogen-Ion Concentration; Hydroxylamine; Hydroxylamines; Hydroxymethylbilane Synthase; Isoelectric Point; Kinetics; Metals; Molecular Sequence Data; Molecular Weight; Porphobilinogen