scholarly journals The reaction pathway of membrane-bound rat liver mitochondrial monoamine oxidase

1973 ◽  
Vol 135 (4) ◽  
pp. 735-750 ◽  
Author(s):  
Miles D. Houslay ◽  
Keith F. Tipton
Keyword(s):  
Monoamine Oxidase ◽  
Reaction Pathway ◽  
Substrate Inhibition ◽  
Mitochondrial Outer Membrane ◽  
Reversible Inhibitors ◽  
Ping Pong ◽  
O2 Concentration ◽  
Mitochondrial Monoamine Oxidase ◽  
Membrane Bound ◽  
Kinetic Investigations

1. A preparation of a partly purified mitochondrial outer-membrane fraction suitable for kinetic investigations of monoamine oxidase is described. 2. An apparatus suitable for varying the O2 concentration in a spectrophotometer cuvette is described. 3. The reaction catalysed by the membrane-bound enzyme is shown to proceed by a double-displacement (Ping Pong) mechanism, and a formal mechanism is proposed. 4. KCN, NaN3, benzyl cyanide and 4-cyanophenol are shown to be reversible inhibitors of the enzyme. 5. The non-linear reciprocal plot obtained with impure preparations of benzylamine, which is typical of high substrate inhibition, is shown to be due to aldehyde contamination of the substrate.

scholarly journals Rat liver mitochondrial monoamine oxidase. A change in the reaction mechanism on solubilization

1975 ◽  
Vol 145 (2) ◽  
pp. 311-321 ◽  
Author(s):  
M D Houslay ◽  
K F Tipton
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Bound State ◽  
Monoamine Oxidase A ◽  
Rate Equations ◽  
British Library ◽  
Ping Pong ◽  
Mitochondrial Monoamine Oxidase ◽  
Lending Library ◽  
Membrane Bound

1. The kinetics of benzylamine oxidation by a soluble preparation of rat liver mitochondrial monoamine oxidase were investigated and were shown to conform to adouble-displacement (or Ping Pong) mechanism. 2. The pathway differs in detail from that followed by other amine oxidases, including the membrane-bound enzyme in rat liver mitochondrial outer membranes. 3. It is suggested taht the conformation of the protein in the soluble state differs from that in the membrane-bound state. 4. The full rate equations for this mechanism have been deposited as Supplementary Publication SUP 50039 (5pages) at the British Library (lending Division) (formely the National Lending Library for Science and Technology), Boston Spa, Yorks, LS237BQ, U.K.. from whom copies can be obtained on the terms indicated in Biochem. J (1975) 145,5.

On hepatic mitochondrial monoamine oxidase activity in lipid deficiency

1979 ◽  
Vol 57 (6) ◽  
pp. 588-594 ◽  
Author(s):  
C. Kandaswami ◽  
A. D'Iorio
Keyword(s):  
Fatty Acids ◽  
Monoamine Oxidase ◽  
Oxidase Activity ◽  
Marked Decrease ◽  
Specific Activity ◽  
Essential Fatty Acids ◽  
Mitochondrial Outer Membrane ◽  
Monoamine Oxidase Activity ◽  
Membrane Enzyme ◽  
Mitochondrial Monoamine Oxidase

A marked decrease in liver mitochondrial monoamine oxidase activity was noticed in rats fed a fat-free diet as compared with that of their controls. In lipid-deprived rats, the specific activity of this enzyme was very low towards different substrates studied. The activity of kynurenine 3-monooxygenase, which like monoamine oxidase is localized on the mitochondrial outer membrane, was similarly depressed under conditions of lipid deprivation. On the other hand no major changes were observed in the activity of the inner membrane enzyme, kynurenine aminotransferase. Mitochondria from fat-free diet-fed rats were deficient in essential fatty acids whereas no appreciable variations were found in the relative proportions of phospholipids in comparison with those of control mitochondria. Mitochondrial monoamine oxidase activity of the deficient rats retained its sensitivities to inhibitor drugs like clorgyline and deprenyl. No changes were noticeable in the substrate specificity of monoamine oxidase in these rats. When we switched the fat-free diet-fed rats to a diet supplemented with a source of essential fatty acids, there was an elevation in the activities of both monoamine oxidase and kynurenine 3-monooxygenase, their levels approaching those of the control rats.

scholarly journals Mitochondrial Monoamine Oxidase

1967 ◽  
Vol 242 (18) ◽  
pp. 4230-4238
Author(s):  
V. Gene Erwin ◽  
Leslie Hellerman
Keyword(s):  
Monoamine Oxidase ◽  
Mitochondrial Monoamine Oxidase

Mechanisms of sulphate activation and transfer

1991 ◽  
Vol 332 (1263) ◽  
pp. 141-148 ◽  
Keyword(s):  
Reaction Pathway ◽  
General Strategy ◽  
Inorganic Pyrophosphate ◽  
Aps Kinase ◽  
Stereochemical Analysis ◽  
Ping Pong ◽  
Inorganic Sulphate ◽  
Widespread Phenomenon ◽  
The Common ◽  
Enzyme Intermediate

Sulphation of natural products is a widespread phenomenon. Inorganic sulphate is transported into cells and activated by ATP sulphurylase, an enzyme that has been studied by kinetic and stereochemical methods. It has been shown that the enzyme catalyses the displacement of inorganic pyrophosphate by inorganic sulphate from Pa of ATP by a direct 'in line’ mechanism. The adenosine 5'-phosphosulphate formed is then phosphorylated at the 3' position by APS kinase to give 3'-phosphoadenosine 5'- phosphosulphate, the common sulphating species in biology. A general strategy for the synthesis of chiral [ 16 O 17 O 18 O]-sulphate esters has been established and a method developed for their stereochemical analysis by using Fourier Transform Infrared Spectroscopy. The stereochemical course of an aryl sulphotransferase from Aspergillus oryzae has been shown to proceed with retention of configuration at sulphur, supporting a ping pong type mechanism with a sulpho-enzyme intermediate on the reaction pathway.

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