Biosynthesis of fatty acids in mammary tissue

Nandedkar, Arvind K.N.; Kumar, Soma

doi:10.1016/0003-9861(69)90318-x

Cited by 36 publications

(5 citation statements)

References 28 publications

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“…For glycerol, the 2-fold increase in glycerol uptake and the decreased [glycerol 3-phosphate] caused by acetoacetate were probably related to the increased [NAD+]/[NADH] ratio in the cytoplasm, which would favour triose phosphate formation from glycerol 3-phosphate. Secondly, the conversion of acetoacetyl-CoA into 3-hydroxybutyryl-CoA in the pathway forming butyryl-CoA, an effective primer for fatty acid synthesis in mammary gland (Nandedkar & Kumar, 1969;Lin & Kumar, 1972; Scheme 1), would be promoted. Thirdly, oxaloacetate reduction in the cytoplasm could occur, and this would remove product from the citrate lyase reaction in addition to providing malate, which could either generate NADPH in the reaction catalysed by 'malic' enzyme or enter the mitochondria to provide more oxaloacetate for the citrate synthase reaction (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Control of glucose metabolism in isolated acini of the lactating mammary gland of the rat. The ability of glycerol to mimic some of the effects of insulin

Robinson¹,

Williamson²

1977

Biochemical Journal

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Inhibition of glucose uptake by acetoacetate and relief of this inhibition by insulin found previously in slices of rat mammary gland [Williamson, McKeown & Ilic (1975) Biochem. J. 150. 145-152] was confirmed in acini, which represent a more homogeneous population of cells. Glycerol (1mM) behaved like insulin (50 minuits/ml) in its ability to relieve the inhibition of glucose (5 mM) utilization caused by acetoacetate (2 mM) in acini. Both glycerol and insulin reversed the increase in [citrate] and the decrease in [glycerol 3-phosphate] and the [lactate]/[pyruvate] ratio in the presence of acetoacetate. Lipogenesis from 3H2O, [3-14C] acetoacetate, [1-14C]- and [6-14C]-glucose was stimulated, whereas 14CO2 formation from [3-14C]acetoacetate was decreased. Neither insulin nor glycerol relieved the acetoacetate inhibition of glucose uptake when lipogenesis was inhibited by 5-(tetradecyloxy)-2-furoic acid. From measurements of [3-14C]acetoacetate incorporation into lipid in the various situations it is suggested that a cytosolic pathway for acetoacetate utilization may exist in rat mammary gland. In the absence of acetoacetate, glycerol inhibited glucose utilization by 60% and increased both [glycerol 3-phosphate] and the [lactate/[pyruvate] ratio. Possible ways in which glycerol may mimic the effects of insulin are discussed.

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Section: Resultsmentioning

confidence: 99%

Control of glucose metabolism in isolated acini of the lactating mammary gland of the rat. The ability of glycerol to mimic some of the effects of insulin

Robinson¹,

Williamson²

1977

Biochemical Journal

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“…However @-oxidative enzymes have been found recently in the cytoplasmic fraction of mammary glands [2,20] and rat liver [l]. These enzymes, probably catalyzing reversible reactions, including acetoacetyl-CoA thiolase, NADH-dependent acetoacetyl-CoA reductase and crotonyl-CoA hydratase, appear to synthesize mainly crotonyl-CoA which is then reduced to butyrate by the fatty acid synthetase [21]. These &dings suggest the possibility that extramitochondrial @-oxidative enzymes may be present in cells of different tissues.…”

Section: Discussionmentioning

confidence: 99%

The β‐Oxidative Cleavage of Long‐Chain Fatty Acids in Rat‐Liver Cytoplasm

Fiecchi¹,

Galli-Kienle²,

Scala³

et al. 1973

European Journal of Biochemistry

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A β‐oxidative cleavage of oleyl‐ and stearyl‐CoA has been obtained with soluble enzymes of rat‐liver homogenate. The transformation requires NAD+ as an oxido‐reductive cofactor and is enhanced by ATP and CoA. Under the reported conditions 2,9‐octadecadienoic, 3,9‐octadecadienoic, 3‐hydroxy‐9‐octadecenoic, 7‐hexadecenoic, 3‐hydroxy‐7‐hexadecenoic and 5‐tetradecenoic acids are present after incubation of oleyl‐CoA, while no detectable amounts of shorter fatty acids are formed. A similar oxidation pattern is obtained with stearyl‐CoA when Mg2+ ions are also added to the system. The cytoplasmic origin of these enzymes is established by comparing their activity with that of the mitochondrial β‐oxidation enzymes.

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“…This is consistent with a principal role for the enzyme in the fl-oxidation of fatty acids. However, cytoplasmic fatty acid synthesis may be initiated by butyryl-CoA rather than acetyl-CoA (Nandekhar & Kumar, 1969;Lin & Kumar, 1972), and the synthesis of butyryl-CoA may require a cytoplasmic 3-hydroxyacyl-CoA dehydrogenase. Such an activity has been found in rabbit mammary gland, and, since the enzyme preferred the D-isomer of 3-hydroxybutyrate, the activity was not due to leakage of mitochondrial enzyme (Nandekhar & Kumar, 1969).…”

Section: Comparative Aspects Of Mammary-gland Enzyme Activities and Intracellular Distributionmentioning

confidence: 99%

“…However, cytoplasmic fatty acid synthesis may be initiated by butyryl-CoA rather than acetyl-CoA (Nandekhar & Kumar, 1969;Lin & Kumar, 1972), and the synthesis of butyryl-CoA may require a cytoplasmic 3-hydroxyacyl-CoA dehydrogenase. Such an activity has been found in rabbit mammary gland, and, since the enzyme preferred the D-isomer of 3-hydroxybutyrate, the activity was not due to leakage of mitochondrial enzyme (Nandekhar & Kumar, 1969). The results of the present investigation (Table 1) suggest that any cytoplasmic 3-hydroxybutyrate dehydrogenase activity would not exceed approx.…”

Section: Comparative Aspects Of Mammary-gland Enzyme Activities and Intracellular Distributionmentioning

confidence: 99%

The activities and intracellular distributions of enzymes of carbohydrate, lipid and ketone-body metabolism in lactating mammary glands from ruminants and non-ruminants

Crabtree¹,

Taylor²,

Coombs³

et al. 1981

Biochemical Journal

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1. The activities of several enzymes of carbohydrate, lipid, acetate and ketone-body metabolism were measured in lactating mammary glands from rats, mice, rabbits, guinea pigs, sows, sheep, cows and goats. The intracellular distributions of many of the enzymes were measured by fractional extraction. 2. Acetyl-CoA synthetase was predominantly cytoplasmic in rats and guinea pigs, but was more mitochondrial in the other species. The different location of this enzyme in rats and mice is discussed in relation to the disposal of reducing equivalents. 3. 3-Oxo acid CoA-transferase and acetoacetyl-CoA thiolase assayed at 600 microM-CoA were predominantly mitochondrial in all species investigated. Acetoacetyl-CoA thiolase assayed at 8 microM-CoA was predominantly cytoplasmic, except in rabbits and guinea pigs. Ruminants appeared to possess little, if any, of the cytoplasmic enzyme. 4. The activities and distributions of NADP-isocitrate dehydrogenase were consistent with a role in supplying cytoplasmic NADPH in ruminant tissue, and indicated that this system may also occur in guinea pigs.

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Biosynthesis of fatty acids in mammary tissue

Cited by 36 publications

References 28 publications

Control of glucose metabolism in isolated acini of the lactating mammary gland of the rat. The ability of glycerol to mimic some of the effects of insulin

Control of glucose metabolism in isolated acini of the lactating mammary gland of the rat. The ability of glycerol to mimic some of the effects of insulin

The β‐Oxidative Cleavage of Long‐Chain Fatty Acids in Rat‐Liver Cytoplasm

The activities and intracellular distributions of enzymes of carbohydrate, lipid and ketone-body metabolism in lactating mammary glands from ruminants and non-ruminants

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