Kinetic analysis of the malonyl coenzyme A decarboxylation and the condensation reaction of fatty acid synthesis. Application to the study of malonyl coenzyme A inactivated chicken liver fatty acid synthetase

Biochemistry ◽  
1981 ◽  
Vol 20 (12) ◽  
pp. 3400-3404 ◽  
Author(s):  
K. R. Srinivasan ◽  
Suriender Kumar
Keyword(s):  
Fatty Acid ◽  
Kinetic Analysis ◽  
Fatty Acid Synthesis ◽  
Coenzyme A ◽  
Condensation Reaction ◽  
Fatty Acid Synthetase ◽  
Acid Synthesis ◽  
Chicken Liver ◽  
Liver Fatty Acid

scholarly journals Inhibition of the condensing component of chicken liver fatty acid synthase by iodoacetamide and 5,5′-dithiobis-(2-nitrobenzoic acid)

1983 ◽  
Vol 215 (3) ◽  
pp. 545-553 ◽  
Author(s):  
E Varagiannis ◽  
S Kumar
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Fatty Acid Synthase ◽  
Condensation Reaction ◽  
Acid Synthesis ◽  
Chicken Liver ◽  
Liver Fatty Acid ◽  
Nitrobenzoic Acid ◽  
Proposed Model ◽  
Cross Links

Chicken liver fatty acid synthase is inhibited by the thiol-modifying reagents 5,5′-dithiobis-(2-nitrobenzoic acid) and iodoacetamide. Total inactivation of the activity for fatty acid synthesis requires the modification of about 8 of the nearly 50 freely accessible thiol groups per molecule. The differential binding of iodo[14C]acetamide to phenylmethylsulphonyl fluoride-modified enzyme in the absence and in the presence of excess acetyl-CoA shows complete modification of one cysteine-SH site of the condensing enzyme and partial modification of the pantetheine-SH site for a total of approx. 1.4 mol of iodoacetamide bound per mol of enzyme. The reaction of the enzyme with 5,5′-dithiobis-(2-nitrobenzoic acid) generates disulphide cross-links for each molecule of the reagent added, but 95% of these cross-links are intrasubunit. Both the iodoacetamide- and 5,5′-dithiobis-(2-nitrobenzoic acid)-modified species catalyse all the component partial reactions of fatty acid synthesis except the condensation reaction. The results obtained with iodoacetamide show that in the dimeric fatty acid synthase modification of one cysteine-SH condensing site and/or one pantetheine-SH site per dimer is sufficient to affect inhibition of condensing activity and the activity for fatty acid synthesis, and are in accord with a recently proposed model for the mechanism of action of animal fatty acid synthases [Kumar (1982) J. Theor. Biol. 95, 263-283].

scholarly journals Ethanol administration and the relationship of malonyl-coenzyme A concentrations to the rate of fatty acid synthesis in rat liver

1973 ◽  
Vol 136 (3) ◽  
pp. 639-647 ◽  
Author(s):  
Robert W. Guynn ◽  
Dulce Veloso ◽  
Raymond L. Harris ◽  
J. W. Randolph Lawson ◽  
Richard L. Veech
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
De Novo ◽  
Fatty Acid Synthetase ◽  
Acid Synthesis ◽  
Ethanol Administration ◽  
Liver Fatty Acid ◽  
Malonyl Coa ◽  
Significant Difference

1. The effect of ethanol on liver fatty acid synthesis was studied in vivo in 24h-starved and ‘meal-fed’ rats (i.e. fed for 3h per day and not ad libitum). 2. In the fed animal3H2O was incorporated into fat at a rate of 0.46μmol of C2 units/min per g wet wt. of liver. Administration of either ethanol (3.2g/kg) or equicaloric amounts of glucose had no effect on the rate of3H2O incorporation into lipid. 3. In the 24h-starved animal, administration of the same dose of ethanol produced an increase in the rate of3H2O incorporation from 0.06 to 0.12μmol of C2 units/min per g fresh wt. after 3h whereas [malonyl-CoA] increased from 0.006 to 0.009μmol/g. Glucose given in amounts equicaloric to ethanol was significantly more lipogenic, increasing both the3H2O incorporation from 0.06 to 0.20μmol of C2 units/min per g and the malonyl-CoA content from 0.006 to 0.013 μmol/g wet wt. at 3h. 4. The decrease in the redox state of free cytoplasm NAD or NADP couples or the changes in content of citrate, glucose 6-phosphate and pyruvate of liver after ethanol administration had no measurable effect on the rate of fatty acid synthesis in vivo. 5. Under the conditions of the experiments there was no significant difference, among any of the groups, in the activity of liver fatty acid synthetase measured in vitro. A double-reciprocal plot of the rate of3H2O incorporation and the total tissue malonyl-CoA concentrations showed a striking relationship. It has been concluded that the rate of fatty acid synthesis in vivo is determined principally by the Vmax. of fatty acid synthetase and the concentration of free malonyl-CoA. 6. It has also been concluded that under the conditions of the present study, the synthesis of fatty acids de novo is unlikely to be an important factor in the increased liver lipid content associated with ethanol administration.

scholarly journals The Condensation Reaction of Fatty Acid Synthesis

1963 ◽  
Vol 238 (2) ◽  
pp. 557-565 ◽  
Author(s):  
A.W. Alberts ◽  
Peter Goldman ◽  
P. Roy Vagelos
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Condensation Reaction ◽  
Acid Synthesis
Sign in / Sign up

Export Citation Format

Share Document