Comparative Studies of the Pigeon Liver Fatty Acid Synthetase Complex and Its Subunits

Kumar, Sunil; Dorsey, Judith A.; Muesing, Richard A.; Porter, John W.

doi:10.1016/s0021-9258(18)62855-8

Cited by 144 publications

(19 citation statements)

References 32 publications

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“…Transferase activity was assayed by the chromatographic detection of radiolabeled acetyl-S-pantetheine formed from [1-14 C]acetyl-CoA and pantetheine (12). β-Ketoacyl reductase and enoyl reductase activities were assayed by observing spectrophotometrically the oxidation of NADPH in the presence of trans-1-decalone (8), or S-crotonyl N-acetylcysteamine (16), respectively. Dehydrase activity was assayed spectrophotometrically at 270 nm using S-D,L-β-hydroxybutyryl N-acetylcysteamine as substrate (16).…”

Section: Methodsmentioning

confidence: 99%

“…β-Ketoacyl reductase and enoyl reductase activities were assayed by observing spectrophotometrically the oxidation of NADPH in the presence of trans-1-decalone (8), or S-crotonyl N-acetylcysteamine (16), respectively. Dehydrase activity was assayed spectrophotometrically at 270 nm using S-D,L-β-hydroxybutyryl N-acetylcysteamine as substrate (16). Thioesterase activity was assessed by measuring the free radiolabeled palmitic acid formed from [1-14 C]palmitoyl-CoA (17).…”

Section: Methodsmentioning

confidence: 99%

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The Malonyl/Acetyltransferase and β-Ketoacyl Synthase Domains of the Animal Fatty Acid Synthase Can Cooperate with the Acyl Carrier Protein Domain of Either Subunit

Joshi¹,

Witkowski²,

Smith³

1998

Biochemistry

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The active form of the animal fatty acid synthase (FAS) is a dimer of identical multifunctional polypeptides, each containing seven discrete functional domains, that cooperate to form two centers for palmitate synthesis. To assess the importance of domain cooperation across the subunit interface in the reaction mechanism, we have utilized a strategy based on complementation analysis in vitro of modified FASs carrying critical mutations in specific catalytic domains. Homodimeric FASs carrying the same mutation(s) in both subunits are unable to synthesize fatty acids. As predicted by the current head-to-tail model for the animal FAS, heterodimeric FASs formed between the acyl carrier protein (ACP) mutant and either the beta-ketoacyl synthase (KS) or malonyl/acetyltransferase (MAT) are active in palmitate synthesis, confirming that the KS and MAT domains can cooperate with the ACP domain of the opposite subunit. Contrary to this model however, heterodimeric FASs formed between the KS and MAT mutants, between a MAT, ACP double mutant, and a KS mutant, and between a KS, ACP double mutant, and a MAT mutant are also active in palmitate synthesis, indicating that the MAT and KS domains can also cooperate with the ACP domain of the same subunit. The results of this study reveal an unanticipated element of redundancy in the FAS reaction mechanism in that the amino-terminal KS and MAT domains can make functional contact with the penultimate carboxy-terminal ACP domain of either subunit. A revised model for the FAS is proposed in which the substrate loading and condensation reactions can be catalyzed either by one of the two subunits or by cooperation between domains across the subunit interface.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Malonyl/Acetyltransferase and β-Ketoacyl Synthase Domains of the Animal Fatty Acid Synthase Can Cooperate with the Acyl Carrier Protein Domain of Either Subunit

Joshi¹,

Witkowski²,

Smith³

1998

Biochemistry

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“…Conditions for the Measurement of the Partial Reactions of Fatty Acid Synthesis. The conditions for all the partial reactions were essentially similar to those described by Kumar et al (1970b). Malonyl-CoA inactivated enzyme was extensively dialyzed to remove excess substrates(s) after which the overall activity for fatty acid synthesis and activities for other partial reactions were measured.…”

Section: Methodsmentioning

confidence: 99%

“…Unlabeled enzyme (2 mg) added to each of the treated enzyme preparations. The procedure for the preparation of peptic peptides and high-voltage electrophoresis of these peptides has been described before (Kumar et al, 1970b). °The studies were carried out at 30 °C at an enzyme concentration of 100 µg/mL.…”

Section: High-voltage Electrophoresis Of Malonyl Peptides Ofmentioning

confidence: 99%

Inactivation of chicken liver fatty acid synthetase by malonyl coenzyme A. Effects of acetyl coenzyme A and nicotinamide adenine dinucleotide phosphate

Kumar¹,

Srinivasan²

1981

Biochemistry

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Chicken liver fatty acid synthetase complex is irreversibly inactivated by one of the substrates, malonyl-CoA. Acetyl-CoA has a dual role. At concentrations less than or comparable to those of malonyl-CoA, the rate of inactivation is enhanced, whereas at acetyl-CoA/malonyl-CoA ratios greater than 2, the rte of inactivation is slowed down. NADP+ at low concentrations (25 microM) affords considerable protection against malonyl-CoA mediated inactivation whereas NAD+ even at 1.0 mM concentration has no effect. The inactivation process does not lead to the dissociation of the enzyme complex and is accompanied by subtle conformational changes as measured by circular dichroism measurements. Of all the model partial reactions, decarboxylation of malonyl-CoA and the condensation--CO2 exchange are the only reactions which are not catalyzed by the modified species. The process of inactivation is accompanied by enhanced covalent binding of malonyl groups such that approximately 6 mol of the acyl group is bound per mol of the enzyme at complete inactivation. The available evidence suggests that the inactivation of the enzyme results from the binding of malonyl group(s) at or near the condensing site of the enzyme.

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“…The supernatant of the homogenate obtained by centrifuging at 500g for 10 min at 4 °C was re-centrifuged at 9000g for 10 min at 4 °C, and further centrifuged at 105 000g for 60 min. The FAS activity was determined in terms of the malonyl-CoA-and acetyl-CoA-dependent oxidation of NADPH according to the methods of Kumar et al and Carey et al24,25 The reaction mixture was composed of a 0.1 M phosphoric acid buffer ( pH 7.0) containing 0.2 mM malonyl-CoA. The rate of decrease in the absorbance at 340 nm was measured.…”

mentioning

confidence: 99%

The anti-obesity and anti-diabetic effects of kaempferol glycosides from unripe soybean leaves in high-fat-diet mice

Zhang²,

et al. 2015

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The present study investigated the anti-obesity and anti-diabetic effects of kaempferol glycoside (KG) fractions which were composed of four kaempferol glycosides and purified from unripe Jindai-soybean (Edamame) leaves in C57BL/6J mice. High fat-fed mice treated with 0.15% dietary KG for 92 days had reduced body weight, adipose tissue and TG levels compared to the high fat-fed control group. KG-treatment also decreased fasting blood glucose, serum HbA1c (hemoglobin A(1c)) levels and improved insulin resistance. Gene expression analysis of the liver showed that KG decreased peroxisome proliferator-activated receptor (PPAR-γ) and sterol regulatory element-binding protein (SREBP-1c) expression. These results suggest that KG reduced the accumulation of adipose tissue, improving hyperlipidemia as well as diabetes in obese mice by increasing lipid metabolism through the downregulation of PPAR-γ and SREBP-1c. Thus, KG may have an anti-obesity and anti-diabetic potential.

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Comparative Studies of the Pigeon Liver Fatty Acid Synthetase Complex and Its Subunits

Cited by 144 publications

References 32 publications

The Malonyl/Acetyltransferase and β-Ketoacyl Synthase Domains of the Animal Fatty Acid Synthase Can Cooperate with the Acyl Carrier Protein Domain of Either Subunit

The Malonyl/Acetyltransferase and β-Ketoacyl Synthase Domains of the Animal Fatty Acid Synthase Can Cooperate with the Acyl Carrier Protein Domain of Either Subunit

Inactivation of chicken liver fatty acid synthetase by malonyl coenzyme A. Effects of acetyl coenzyme A and nicotinamide adenine dinucleotide phosphate

The anti-obesity and anti-diabetic effects of kaempferol glycosides from unripe soybean leaves in high-fat-diet mice

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