Non-Essential Activation of Rat Liver Porphobilinogen-Deaminase by Folic Acid

• Published in: Zeitschrift für Naturforschung C. A journal of biosciences Vol. 47; no. 5; pp. 416 - 419
• Main Authors: Noriega, Guillermo O., Juknat, Adela A., Batlle, Alcira M. del C.
• Format: Journal Article
• Language: English
• Published: Tübingen Verlag der Zeitschrift für Naturforschung 01.06.1992
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Cell Fractionation; Cosynthetase; Cytosol - enzymology; Enzyme Activation; Enzymes and enzyme inhibitors; Folic Acid; Folic Acid - pharmacology; Fundamental and applied biological sciences. Psychology; Hydroxymethylbilane Synthase - isolation & purification; Hydroxymethylbilane Synthase - metabolism; Kinetics; Liver - enzymology; Lyases; Male; Models, Theoretical; Nonessential Activation; Porphobilinogen-Deaminase; Protein Binding; Rats; Rats, Inbred Strains; Uroporphyrinogen I; Vertebrata; Mammalia; Enzymatic activity; Rat; Enzyme; Liver; Rodentia; Uroporphyrinogen I synthase; Activation; Kinetic parameter; Folic acid
• ISSN: 0939-5075; 1865-7125
• DOI: 10.1515/znc-1992-0616

This report demonstrates the ability of folic acid to activate rat liver porphobilinogen-deaminase (PBG -D). Lineweaver-Burk analysis revealed an increase in V (38%) without affecting the K . In the concentration range assayed, secondary replots of 1/Δslope and 1/Δintersect versus 1/[folic acid] yielded straight lines, indicating the binding of a single molecule of activator to the enzyme PBG-D , with a K = 1.66 mᴍ. Results presented here show that folic acid acts as a non-essential activator (α = 1; β = 1.6). The activating effect of folic acid has been observed employing the 35-70% ammonium sulphate precipitated fraction, desalted by dialysis or gel filtration, whereas no action was detected when other partially purified PBG -D preparations were utilized as the enzyme source, suggesting either the presence of sites saturated for the activator, or the existence of a different structural protein conformation, or both.