scholarly journals Oxidative phosphorylation. The specific binding of trimethyltin and triethyltin to rat liver mitochondria

1970 ◽  
Vol 118 (1) ◽  
pp. 171-179 ◽  
Author(s):  
W. N. Aldridge ◽  
B. W. Street
Keyword(s):  
Adipose Tissue ◽  
Oxidative Phosphorylation ◽  
Brown Adipose Tissue ◽  
Binding Site ◽  
Rat Liver ◽  
Specific Binding ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Affinity Constants ◽  
Brown Adipose

1. The binding of trimethyltin and triethyltin to rat liver mitochondria was determined and the results were analysed by the method of Scatchard (1949). 2. One binding site (site 1) has the correct characteristics for the site to which trimethyltin and triethyltin are attached when they inhibit oxidative phosphorylation. For each compound the concentration of site 1 is 0.8nmol/mg of protein and the ratios of their affinity constants are the same as the ratio of the concentrations inhibiting oxidative phosphorylation. 3. Binding site 1 is present in a fraction derived from mitochondria containing only 15% of the original protein. In this preparation ultrasonication rapidly destroyed site 1. 4. Dimethyltin and diethyltin do not prevent binding of triethyltin to rat liver mitochondria, whereas triethyl-lead does. 5. Trimethyltin and triethyltin bind to mitochondria from brown adipose tissue and the results indicate a binding site 1 similar to that in rat liver mitochondria. 6. The advantages and limitations of this approach to the study of inhibitors are discussed.

scholarly journals Immunochemical studies with soluble and mitochondrial pyruvate carboxylase activities from rat tissues

1970 ◽  
Vol 119 (4) ◽  
pp. 735-742 ◽  
Author(s):  
F. J. Ballard ◽  
R. W. Hanson ◽  
Lea Reshef
Keyword(s):  
Adipose Tissue ◽  
Mammary Gland ◽  
Brown Adipose Tissue ◽  
Rat Liver ◽  
White Adipose Tissue ◽  
Pyruvate Carboxylase ◽  
Specific Activity ◽  
Rat Liver Mitochondria ◽  
Rat Tissues ◽  
Brown Adipose

1. Pyruvate carboxylase (EC 6.4.1.1), purified from rat liver mitochondria to a specific activity of 14 units/mg, was used for the preparation of antibodies in rabbits. 2. Tissue distribution studies showed that pyruvate carboxylase was present in all rat tissues that were tested, with considerable activities both in gluconeogenic tissues such as liver and kidney and in tissues with high rates of lipogenesis such as white adipose tissue, brown adipose tissue, adrenal gland and lactating mammary gland. 3. Immunochemical titration experiments with the specific antibodies showed no differences between the inactivation of pyruvate carboxylase from mitochondrial or soluble fractions of liver, kidney, mammary gland, brown adipose tissue or white adipose tissue. 4. The antibodies were relatively less effective in reactions against pyruvate carboxylase from sheep liver than against the enzyme from rat tissues. 5. Pyruvate carboxylase antibodies did not inactivate either propionyl-CoA carboxylase or acetyl-CoA carboxylase from rat liver. 6. It is concluded that pyruvate carboxylase in lipogenic tissues is similar antigenically to the enzyme in gluconeogenic tissues and that the soluble activities of pyruvate carboxylase detected in many rat tissues do not represent discrete enzymes but are the result of mitochondrial damage during tissue homogenization.

K+-H+ exchange and volume homeostasis in brown adipose tissue mitochondria

1986 ◽  
Vol 251 (4) ◽  
pp. R787-R793 ◽  
Author(s):  
D. J. DiResta ◽  
K. P. Kutschke ◽  
M. D. Hottois ◽  
K. D. Garlid
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Ionophore A23187 ◽  
Brown Adipose ◽  
Efflux Mechanism ◽  
Exchange Activity

K+-H+ exchange activity in hamster brown adipose tissue mitochondria is activated following depletion of matrix Mg2+ with the divalent cation ionophore A23187. Quinine inhibits K+-H+ exchange reversibly with an I50 of 22 microM, whereas mild treatment with N,N'-dicyclohexylcarbodiimide (DCCD) inhibits this activity irreversibly. In an attempt to label and identify the K+-H+ antiporter protein, brown adipose tissue mitochondria were incubated with [14C]DCCD and subjected to denaturing polyacrylamide gel electrophoresis and fluorography. We observed a labeled band of relative mol wt, 78,000, which satisfies criteria established in rat liver mitochondria for the identification of this carrier (W. H. Martin et al., J. Biol. Chem. 259: 2062-2065, 1984). Thus Mg2+ and quinine each protect the K+-H+ exchanger against both inhibition and binding by DCCD. Volume homeostasis in brown adipose tissue mitochondria, as in other mitochondria, requires a balance between K+ influx and efflux. We propose that regulation of the K+-H+ antiporter, the primary K+ efflux mechanism, plays a major role in this process.

Sign in / Sign up

Export Citation Format

Share Document