Biomaterial Database

Mechanism of the magnesium ion activation of the catalytic activity of horse liver aldehyde dehydrogenase. 1980

K Takahashi, and C S Brown, and H Weiner

The activity of the pI 5 isozyme of horse liver aldehyde dehydrogenase is markedly enhanced by some divalent metal ions (Ca, Mn, Mg), inhibited by others (Fe, Cu, Cd), totally inhibited by Hg, and not significantly affected by still others (Zn, Ni, Co). Steady-state kinetics show that with 0.5 mM Mg or Mn a 2-fold activation of the velocity measured at pH 7.5 occurs when propionaldehyde is the substrate. In the pre-steady state, the magnitude burst of NADH formulation is increased from 2 moles formed per mole of tetrameric enzyme to 4 moles formed in the presence of Mg. The stoichiometry of coenzyme (NADH, NAD, epsilon-NAD) binding is also increased from essentially 2 moles binding to 4 moles binding per mole enzyme in the presence of Mg. It appears that the enzyme exhibits half of the site reactivity in the absence of metal but has a full complement of catalytic sites in the presence.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008670	Metals	Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)	Metal
D009243	NAD	A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)	Coenzyme I,DPN,Diphosphopyridine Nucleotide,Nadide,Nicotinamide-Adenine Dinucleotide,Dihydronicotinamide Adenine Dinucleotide,NADH,Adenine Dinucleotide, Dihydronicotinamide,Dinucleotide, Dihydronicotinamide Adenine,Dinucleotide, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide,Nucleotide, Diphosphopyridine
D002384	Catalysis	The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.	Catalyses
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D006736	Horses	Large, hoofed mammals of the family EQUIDAE. Horses are active day and night with most of the day spent seeking and consuming food. Feeding peaks occur in the early morning and late afternoon, and there are several daily periods of rest.	Equus caballus,Equus przewalskii,Horse, Domestic,Domestic Horse,Domestic Horses,Horse,Horses, Domestic
D000445	Aldehyde Oxidoreductases	Oxidoreductases that are specific for ALDEHYDES.	Aldehyde Oxidoreductase,Oxidoreductase, Aldehyde,Oxidoreductases, Aldehyde
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia