scholarly journals Studies of medium-chain fatty acyl-coenzyme A synthetase. Enzyme fraction II: mechanism of reaction and specific properties

1968 ◽  
Vol 109 (2) ◽  
pp. 283-292 ◽  
Author(s):  
J. Bar-Tana ◽  
G. Rose
Keyword(s):  
Kinetic Study ◽  
Fatty Acyl ◽  
Partial Reaction ◽  
Enzyme Fraction ◽  
Mechanism Of Reaction ◽  
Ping Pong ◽  
Fraction I ◽  
Acyl Coenzyme A ◽  
Liver Fraction ◽  
Allosteric Properties

1. The mechanism of reaction of fatty acyl-CoA synthesis catalysed by fatty acyl-CoA synthetase from ox liver (fraction II; Bar-Tana, Rose & Shapiro, 1968) was investigated by a kinetic study of CoA disappearance dependent on butyrate plus ATP or butyryl-AMP (overall and partial reaction b respectively). 2. Contrary to findings with another enzyme (fraction I), a Bi Uni Uni Bi Ping Pong mechanism (Cleland, 1963a,b,c) corresponding to Berg's (1956) scheme of reaction was eliminated and an ordered Ter Ter mechanism with an A–C–B (standing for ATP, CoA and butyrate respectively) sequence of substrate entry for the overall reaction was established for fraction II. Partial reaction (b) was found to follow the ‘Iso-Theorell–Chance’ mechanism. 3. Also, in contrast with results obtained with fraction I, no allosteric properties could be demonstrated with fraction II.

scholarly journals Studies on medium-chain fatty acyl-coenzyme A synthetase. Enzyme fraction I: mechanism of reaction and allosteric properties

1968 ◽  
Vol 109 (2) ◽  
pp. 275-282 ◽  
Author(s):  
J. Bar-Tana ◽  
G. Rose
Keyword(s):  
Reaction Scheme ◽  
Fatty Acyl ◽  
Formation Reaction ◽  
Partial Reaction ◽  
Enzyme Fraction ◽  
Mechanism Of Reaction ◽  
Ping Pong ◽  
Fraction I ◽  
Acyl Coenzyme A ◽  
Allosteric Properties

1. The mechanism of butyrate activation catalysed by an enzyme fraction derived from ox liver particles (fraction I; Bar-Tana, Rose & Shapiro, 1968) was studied by an analysis of the initial-velocity pattern of the overall reaction and found to conform to the Bi Uni Uni Bi Ping Pong model (Cleland, 1963a,b,c) in agreement with the reaction scheme proposed by Berg (1956). 2. A homotropic co-operative effect was exerted by CoA on fraction I, whereas ATP and AMP functioned as heterotropic co-operative ligands with respect to butyryl-AMP-dependent CoA disappearance. On the other hand, PPi and butyryl-CoA showed antagonistic heterotropic effects when tested under similar conditions. With respect to the overall reaction CoA and ATP could be shown to function as co-operative homotropic modifiers. 3. Two interchangeable conformational states of the enzyme are therefore presumed to exist, state R, having a higher affinity for CoA and ATP and thus preferentially catalysing butyryl-AMP-dependent CoA disappearance (partial reaction b), and state T, favoured by the presence of PPi, catalysing the formation of ATP from butyryl-AMP and PPi (partial reaction a) with greater efficiency. 4. These findings serve to explain the opposite effects of ATP on the partial reactions, as well as the inhibition by CoA and ATP of ATP formation (reaction a) and by PPi of the butyryl-AMP-dependent CoA disappearance (reaction b) (Bar-Tana et al. 1968). 5. The possible analogy of these observations to amino acid-activating and other similar systems is discussed.

scholarly journals Studies on medium-chain fatty acyl-coenzyme A synthetase. Purification and properties

1968 ◽  
Vol 109 (2) ◽  
pp. 269-274 ◽  
Author(s):  
J. Bar-Tana ◽  
G. Rose ◽  
B. Shapiro
Keyword(s):  
Gel Filtration ◽  
Fatty Acyl ◽  
Enzyme Preparations ◽  
Medium Chain ◽  
Atp Formation ◽  
Low Concentrations ◽  
Purification And Properties ◽  
Fraction I ◽  
Acyl Coenzyme A ◽  
Relationship Of

1. Medium-chain fatty acyl-CoA synthetase (EC 6.2.1.2) was isolated by the method of Mahler, Wakil & Bock (1953) and the enzyme activity determined by the disappearance of CoA in the presence either of butyrate and ATP or of butyryl-AMP, as well as by ATP formation from butyryl-AMP and PPi. 2. Preincubation of the enzyme with CoA and ATP alone or together, followed by the removal of these substrates by gel filtration, caused a marked inhibition of ATP formation, contrary to results previously obtained with palmitoyl-CoA synthetase. 3. The effect of ATP on butyryl-AMP-dependent CoA disappearance was inconsistent. Low concentrations of ATP (0·1–0·5mm) always caused inhibition, whereas higher concentrations (5–10mm) activated in some enzyme preparations and inhibited in others. 4. This inconsistency was shown to be due to the presence of two enzyme fractions. Both fractions had similar activities when assayed by the butyryl-AMP- or butyrate-plus-ATP-dependent CoA disappearance. However, fraction I was activated by ATP as measured by butyryl-AMP-dependent CoA disappearance whereas fraction II was inhibited by it. Fraction I also catalysed ATP formation from butyryl-AMP and PPi whereas fraction II was lacking in such activity. 5. The relationship of these observations with respect to other known mechanisms of fatty acid-activating systems is discussed.

scholarly journals Hepatocellular and Hepatic Peroxisomal Alterations in Mice with a Disrupted Peroxisomal Fatty Acyl-coenzyme A Oxidase Gene

1996 ◽  
Vol 271 (40) ◽  
pp. 24698-24710 ◽  
Author(s):  
Chun-Yang Fan ◽  
Jie Pan ◽  
Ruiyin Chu ◽  
Denise Lee ◽  
Kimberly D. Kluckman ◽  
...  
Keyword(s):  
Coenzyme A ◽  
Fatty Acyl ◽  
Oxidase Gene ◽  
Acyl Coenzyme A

scholarly journals Mdm1 maintains endoplasmic reticulum homeostasis by spatially regulating lipid droplet biogenesis

2019 ◽  
Vol 218 (4) ◽  
pp. 1319-1334 ◽  
Author(s):  
Hanaa Hariri ◽  
Natalie Speer ◽  
Jade Bowerman ◽  
Sean Rogers ◽  
Gang Fu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Fatty Acyl ◽  
Nutrient Depletion ◽  
Coenzyme A Ligase ◽  
Response To Stress ◽  
Acyl Coenzyme A ◽  
Er Homeostasis

Lipid droplets (LDs) serve as cytoplasmic reservoirs for energy-rich fatty acids (FAs) stored in the form of triacylglycerides (TAGs). During nutrient stress, yeast LDs cluster adjacent to the vacuole/lysosome, but how this LD accumulation is coordinated remains poorly understood. The ER protein Mdm1 is a molecular tether that plays a role in clustering LDs during nutrient depletion, but its mechanism of function remains unknown. Here, we show that Mdm1 associates with LDs through its hydrophobic N-terminal region, which is sufficient to demarcate sites for LD budding. Mdm1 binds FAs via its Phox-associated domain and coenriches with fatty acyl–coenzyme A ligase Faa1 at LD bud sites. Consistent with this, loss of MDM1 perturbs free FA activation and Dga1-dependent synthesis of TAGs, elevating the cellular FA level, which perturbs ER morphology and sensitizes yeast to FA-induced lipotoxicity. We propose that Mdm1 coordinates FA activation adjacent to the vacuole to promote LD production in response to stress, thus maintaining ER homeostasis.

scholarly journals A Fatty Acyl Coenzyme A Reductase Promotes Wax Ester Accumulation in Rhodococcus jostii RHA1

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
James Round ◽  
Raphael Roccor ◽  
Shu-Nan Li ◽  
Lindsay D. Eltis
Keyword(s):  
Specific Activity ◽  
Dry Weight ◽  
Fatty Acyl ◽  
Wax Esters ◽  
Wax Ester ◽  
Wild Type ◽  
Considerable Potential ◽  
Commodity Chemicals ◽  
Acyl Coenzyme A ◽  
Rhodococcus Jostii

ABSTRACT Many rhodococci are oleaginous and, as such, have considerable potential for the sustainable production of lipid-based commodity chemicals. Herein, we demonstrated that Rhodococcus jostii RHA1, a soil bacterium that catabolizes a wide range of organic compounds, produced wax esters (WEs) up to 0.0002% of its cellular dry weight during exponential growth on glucose. These WEs were fully saturated and contained primarily 31 to 34 carbon atoms. Moreover, they were present at higher levels during exponential growth than under lipid-accumulating conditions. Bioinformatics analyses revealed that RHA1 contains a gene encoding a putative fatty acyl coenzyme A (acyl-CoA) reductase (FcrA). The purified enzyme catalyzed the NADPH-dependent transformation of stearoyl-CoA to stearyl alcohol with a specific activity of 45 ± 3 nmol/mg · min and dodecanal to dodecanol with a specific activity of 5,300 ± 300 nmol/mg · min. Deletion of fcrA did not affect WE accumulation when grown in either carbon- or nitrogen-limited medium. However, the ΔfcrA mutant accumulated less than 20% of the amount of WEs as the wild-type strain under conditions of nitric oxide stress. A strain of RHA1 overproducing FcrA accumulated WEs to ∼13% cellular dry weight under lipid-accumulating conditions, and their acyl moieties had longer average chain lengths than those in wild-type cells (C17 versus C16). The results provide insight into the biosynthesis of WEs in rhodococci and facilitate the development of this genus for the production of high-value neutral lipids. IMPORTANCE Among the best-studied oleaginous bacteria, rhodococci have considerable potential for the sustainable production of lipid-based commodity chemicals, such as wax esters. However, many aspects of lipid synthesis in these bacteria are poorly understood. The current study identifies a key enzyme in wax ester synthesis in rhodococci and exploits it to significantly improve the yield of wax esters in bacteria. In so doing, this work contributes to the development of novel bioprocesses for an important class of oleochemicals that may ultimately allow us to phase out their unsustainable production from sources such as petroleum and palm oil.

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