scholarly journals Liver monoamine oxidase in the obese–hyperglycaemic (ob/ob) mouse

1979 ◽  
Vol 177 (3) ◽  
pp. 943-949 ◽  
Author(s):  
J H Tong ◽  
M Limson-Zamora ◽  
A D'Iorio ◽  
N Bégin-Heick
Keyword(s):  
Enzyme Activity ◽  
Monoamine Oxidase ◽  
Rat Liver ◽  
Mouse Liver ◽  
Specific Activity ◽  
Residual Activity ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Marker Enzymes ◽  
Acetone Water

1. The specific activity of monoamine oxidase was found to be greater in liver mitochondria from ob/ob mice than from lean mice. The activities of marker enzymes were similar in both tissues. 2. Experiments with various substrates (5-hydroxytryptamine, benzylamine and tyramine) and inhibitors (clorgyline and deprenyl) indicated that, unlike rat liver mitochondria, mouse liver mitochondria contain a predominance of the B-form of monoamine oxidase. 3. The Km values for lean and ob/ob mice were the same for any given substrate and were in the increasing order 5-hydroxytryptamine less than tyramine less than benzylamine. Vmax. was approximately 50% greater in obese than in lean mice. 4. Extraction of liver mitochondria with acetone/water or acetone/water/NH3 to remove lipids decreased the enzyme activity relatively more in obese- than in lean-mice preparations, but residual activity was the same in both preparations.

scholarly journals Re-evaluation of the interaction of malonyl-CoA with the rat liver mitochondrial carnitine palmitoyltransferase system by using purified outer membranes

1990 ◽  
Vol 267 (1) ◽  
pp. 85-90 ◽  
Author(s):  
M P Kolodziej ◽  
V A Zammit
Keyword(s):  
Rat Liver ◽  
Specific Activity ◽  
Liver Mitochondria ◽  
Subsequent Treatment ◽  
Carnitine Palmitoyltransferase ◽  
Rat Liver Mitochondria ◽  
Outer Membranes ◽  
High Affinity ◽  
Malonyl Coa ◽  
Order Of Magnitude

1. The interaction of malonyl-CoA with the outer carnitine palmitoyltransferase (CPT) system of rat liver mitochondria was re-evaluated by using preparations of highly purified outer membranes, in the light of observations that other subcellular structures that normally contaminate crude mitochondrial preparations also contain malonyl-CoA-sensitive CPT activity. 2. In outer-membrane preparations, which were purified about 200-fold with respect to the inner-membrane-matrix fraction, malonyl-CoA binding was largely accounted for by a single high-affinity component (KD = 0.03 microM), in contrast with the dual site (low- and high-affinity) previously found with intact mitochondria. 3. There was no evidence that the decreased sensitivity of CPT to malonyl-CoA inhibition observed in outer membranes obtained from 48 h-starved rats (compared with those from fed animals) was due to a decreased ratio of malonyl-CoA binding to CPT catalytic moieties. Thus CPT specific activity and maximal high-affinity [14C]malonyl-CoA binding (expressed per mg of protein) were increased 2.2- and 2.0-fold respectively in outer membranes from 48 h-starved rats. 4. Palmitoyl-CoA at a concentration that was saturating for CPT activity (5 microM) decreased the affinity of malonyl-CoA binding by an order of magnitude, but did not alter the maximal binding of [14C]malonyl-CoA. 5. Preincubation of membranes with either tetradecylglycidyl-CoA or 2-bromopalmitoyl-CoA plus carnitine resulted in marked (greater than 80%) inhibition of high-affinity binding, concurrently with greater than 95% inhibition of CPT activity. These treatments also unmasked an effect of subsequent treatment with palmitoyl-CoA to increase low-affinity [14C]malonyl-CoA binding. 6. These data are discussed in relation to the possible mechanism of interaction between the malonyl-CoA-binding site and the active site of the enzyme.

Evidence for the Biosynthetic Difference between Isolated Mitochondria and Microsomes from Guinea-Pig and Rat Liver Regarding Lysophospharidic Acid, Phosphatidic Acid, CDP-Diglyceride, Phosphatidylglycerol, and Cardiolipin

1974 ◽  
Vol 52 (10) ◽  
pp. 936-939 ◽  
Author(s):  
J. B. Davidson ◽  
N. Z. Stanacev
Keyword(s):  
Guinea Pig ◽  
Phosphatidic Acid ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Marker Enzymes ◽  
Synthetic Enzymes ◽  
Isolated Mitochondria ◽  
Significant Difference ◽  
Nadph Cytochrome C Reductase

The enzymatic activities of marker enzymes (NADPH – cytochrome c reductase and glucose-6-phosphatase) and synthetic enzymes (acyl-CoA:sn-glycero-3-phosphate acyltransferase, CTP:sn-3-phosphatidic acid cytidyltransferase, and CDP-diglyceride:sn-glycero-3-phosphate phosphatidyltransferase) were measured in both isolated mitochondria and microsomes from liver of guinea pig and rat. Results thus obtained show a significant difference in activities of these enzymes between subcellular particles within species and between two examined species. The activity of acyl-CoA:glycero-3-phosphate acyltransferase in guinea-pig mitochondria parallels the activity of microsomal marker enzymes in this fraction, while in rat liver mitochondria the activity is relatively higher and cannot be accounted for by the microsomal content as determined by marker enzymes. Implications of these results regarding mitochondrial autonomy in the biosynthesis of polyglycero-phosphatides and their precursors are discussed.

Action of khimcoccid on monoamine oxidase of rat liver mitochondria

1982 ◽  
Vol 16 (2) ◽  
pp. 77-82
Author(s):  
V. I. Zaionts ◽  
L. A. Korovitskaya ◽  
E. B. Nikol'skaya ◽  
O. V. Yagodina
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria

scholarly journals Carnitine palmitoyltransferase activities (EC 2.3.1.–) of rat liver mitochondria

1970 ◽  
Vol 119 (3) ◽  
pp. 547-552 ◽  
Author(s):  
D. W. Yates ◽  
P. B. Garland
Keyword(s):  
Rat Liver ◽  
Specific Activity ◽  
Liver Mitochondria ◽  
Carnitine Palmitoyltransferase ◽  
Rat Liver Mitochondria ◽  
Type I ◽  
Type Ii ◽  
Inner Mitochondrial Membrane ◽  
Group Transfer ◽  
Carnitine Palmitoyltransferase Activity

1. A continuously recording and sensitive fluorimetric assay is described for carnitine palmitoyltransferase. This assay has been applied to whole or disintegrated mitochondria and to soluble protein fractions. 2. When rat liver mitochondria had been disintegrated by ultrasound, the specific activity of carnitine palmitoyltransferase was 15–20m-units/mg of protein. Only one-fifth of this activity was assayable (with added substrates) before mitochondrial disintegration. 3. It is concluded that there are two carnitine palmitoyltransferase activities in rat liver mitochondria, of which one (type I) is relatively superficial in location and catalyses an acyl-group transfer between added CoA and carnitine, whereas the other (type II) is less superficial and catalyses an acyl-group transfer in unbroken mitochondria between added carnitine and intramitochondrial CoA. The existence of two distinct carnitine palmitoyltransferases was predicted by Fritz & Yue (1963). 4. In unbroken mitochondria, type I transferase is accessible to the inhibitor 2-bromostearoyl-CoA whereas the type II transferase is inaccessible. 5. A major part of the total carnitine palmitoyltransferase activity of rat liver mitochondria is membrane-bound and of type II. 6. These observations, when considered in conjunction with the penetration of mitochondria by CoASH or carnitine, indicate that the type II transferase is attached to the inner mitochondrial membrane.

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