Fatty acid esterifying enzymes in rat adipose tissue homogenates

1968 ◽  
Vol 46 (9) ◽  
pp. 1039-1045 ◽  
Author(s):  
Anna M. Daniel ◽  
David Rubinstein
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Acid Phosphatase ◽  
Chain Length ◽  
Significant Alteration ◽  
Ph Optimum ◽  
Tissue Homogenates ◽  
Rat Adipose Tissue

Some characteristics of enzymes in homogenates of rat adipose tissue concerned with esterification of fatty acids have been investigated. Acyl-CoA thiokinase is the most active of the enzymes studied, with optimal concentrations of palmitate and ATP being 2 mM and 25 mM respectively. The thiokinase has a pH optimum between 8 and 10 and reacts with fatty acids ranging in chain length from C4 to C22, with the greatest activity towards palmitate. About 50% of the activity is found in the 100 000 × g supernatant. Acyl-CoA : α-glycerolphosphate acyltransferase and acyl-CoA deacylase have pH optima between 7 and 8. Albumin at a concentration of 1% activates the former, while the latter is inhibited by concentrations of albumin greater than 0.5%. Deacylase activity is found almost entirely in the 100 000 × g supernatant. Both the acyl-CoA : α-glycerolphosphate acyltransferase and the acyl-CoA : diglyceride acyltransferase lose much of their activity upon fractionation. The pH optimum of the acyl-CoA : diglyceride acyltransferase ranges from pH 7 to 9, while that of the phosphatidc acid phosphatase is 6. The latter enzyme is distributed equally between particulate and soluble portions of the homogenate. When these enzymes are assayed in homogenates from fed and fasted animals, a significant alteration is found only in the level of acyl-CoA deacylase, which is decreased. The properties of these enzymes can be related to the extent and type of esterification in homogenates from fed and fasted animals.

Microsomal glycerolphosphate acyltransferase inactivation by fatty acids

1990 ◽  
Vol 68 (9) ◽  
pp. 1255-1260 ◽  
Author(s):  
V. Durocher ◽  
M. Miller ◽  
M. A. Rodriguez
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Serum Albumin ◽  
Membrane Lipids ◽  
Lipid Synthesis ◽  
Acyltransferase Activity ◽  
Molar Ratios ◽  
Rat Adipose Tissue

Glycerolphosphate acyltransferase activity in microsomes from rat adipose tissue is shown to decrease with time upon incubation with adipose tissue cytosolic fraction. The inactivation can be prevented with serum albumin and seems to be caused by an increase in endogenous free fatty acid as a consequence of the action of cytosolic lipase(s) on the membrane lipids. Similar inactivation can be observed after short incubation of microsomes with oleic acid at micromolar concentrations. Diacylglycerol acyltransferase is also inhibited by oleic acid, although to a lesser degree. In contrast, glucose-6-phosphatase and NADPH – cytochrome reductase activities are not changed. The oleic acid effect appears to occur upon binding to the microsomal membranes and can be prevented by bovine serum albumin at protein/fatty acid molar ratios above one. These results suggest that free fatty acids may be involved in the modulation of triacylglycerol synthetic enzymes.Key words: glycerolphosphate acyltransferase, fatty acids, microsomal enzymes, lipid synthesis.

Relation of fatty acid structure to release and esterification of free fatty acids

1963 ◽  
Vol 205 (5) ◽  
pp. 909-912 ◽  
Author(s):  
C. H. Hollenberg ◽  
A. Angel
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Free Fatty Acids ◽  
Chain Length ◽  
Binding Sites ◽  
Free Acid ◽  
Aqueous Solubility ◽  
Subsequent Exposure ◽  
Rat Adipose Tissue ◽  
Acid Structure

After incubation of rat adipose tissue with corticotrophin in buffer-albumin, the composition of the free fatty acids (FFA) in the tissue and in the medium was determined; the medium contained proportionately more myristic, palmitoleic, linoleic, and linolenic acids. The ratio of the amount of each free acid in the medium to that in the tissue increased with decreasing chain length and increasing unsaturation. Free acids produced in adipose tissue by corticotrophin stimulation were esterified by subsequent exposure of the tissue to glucose and insulin. Among the saturated and monoenoic acids the shorter chain components were esterified to a greater extent, while at a given chain length the more unsaturated acids were more readily esterified. Thus the more polar FFA were more readily released from and esterified in adipose tissue. These results could have been produced by a variety of processes including differences between the acids in aqueous solubility or the presence of tissue-binding sites with varying affinities for the different acids.

scholarly journals Selective release of human adipocyte fatty acids according to molecular structure

1997 ◽  
Vol 324 (3) ◽  
pp. 911-915 ◽  
Author(s):  
Thierry RACLOT ◽  
Dominique LANGIN ◽  
Max LAFONTAN ◽  
René GROSCOLAS
Keyword(s):  
Molecular Structure ◽  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Chain Length ◽  
Animal Studies ◽  
Essential Fatty Acids ◽  
Monounsaturated Fatty Acids ◽  
Fat Cells ◽  
Obese Women

The objective of the present study was to investigate the mobilization of individual fatty acids from human white fat cells. Mammary adipose tissue from eight healthy non-obese women in their normal dietary state was collected, and isolated adipocytes were incubated with lipolytic agents. The mobilization of 34 individual fatty acids was measured by comparing the composition of non-esterified fatty acids (NEFA) with that of the triacylglycerols (TAG) from which they originated through lipolysis. Compared with TAG, NEFA were enriched in some polyunsaturated fatty acids with 18–20 carbon atoms. Conversely, the percentage of very-long-chain (20–22 carbon atoms) saturated and monounsaturated fatty acids was approx. 2 times lower in NEFA than in TAG. The relative mobilization (% in NEFA/% in TAG) of the most readily mobilized fatty acid (C20:5,n-3; 2.25) was more than 6-fold higher than that of the least readily mobilized (C22:1,n-11; 0.37). Relationships were found between the molecular structure of fatty acids and their mobilization rate. For a given chain length, the relative mobilization rate increased with increasing unsaturation, whereas for a given unsaturation, it decreased with increasing chain length. The relative mobilization rate for essential fatty acids decreased in the following order: C20:5,n-3 > C20:4,n-6 > C18:3,n-3 > C18:2,n-6 > C22:6,n-3. Interestingly, C20:5,n-3 and C20:4,n-6, which are respectively precursors of the 3- and 2-series of prostaglandins, were preferentially mobilized. It is concluded that fatty acids are selectively mobilized from human fat cells according to molecular structure, in full agreement with animal studies. By modulating the qualitative fatty acid supply to organs and by remodelling the fatty acid composition of adipose tissue, this selectivity would be relevant for consideration in physiology, health and epidemiology.

scholarly journals Selective mobilization of fatty acids from white fat cells: evidence for a relationship to the polarity of triacylglycerols

1997 ◽  
Vol 322 (2) ◽  
pp. 483-489 ◽  
Author(s):  
Thierry RACLOT
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid ◽  
Chain Length ◽  
Wide Spectrum ◽  
Fat Cells ◽  
Double Bonds ◽  
Fat Cell ◽  
Relative Enrichment ◽  
White Fat

Fatty acids are selectively released from white fat cells in accordance with well-defined rules relating their molecular structure and their mobilization rate, emphasizing the possible role of their physicochemical properties. Lipolysis is widely reported to work for conditions where only small amounts of substrate are available. We hypothesize that the preferential hydrolysis of a substrate fraction enriched in the most polar triacylglycerols (TAGs) reflects the pattern of selective fatty acid mobilization. Rat adipose tissue was first manipulated by dietary means to obtain a wide spectrum of fatty acids. Fat cell TAGs were separated into eight fractions according to polarity by liquid–liquid partition chromatography and their fatty acid proportions and compositions were determined by GLC. In the most polar TAG fractions, the relative enrichment of fatty acids (percentage in a TAG fraction divided by percentage in total TAGs) increased with the number of double bonds for a given chain length, whereas it decreased with increasing chain length for a given degree of unsaturation. The relative enrichment of highly mobilized fatty acids (16–20 carbon atoms and four or five double bonds) was very high (more than 2.5) in the most polar TAG fractions, whereas that of weakly mobilized fatty acids (20–24 carbon atoms and no or one double bond) was very low (less than 0.5). The relative enrichment of moderately mobilized fatty acids (comprising all the others) was close to unity. Our study shows that the relative enrichment of fatty acids in the most polar adipose tissue TAGs is consistent with their relative mobilization rates. This supports our hypothesis and raises the possibility that the molecular species of TAGs might be one of the regulating factors.

Selectivity of fatty acid mobilization: a general metabolic feature of adipose tissue

1995 ◽  
Vol 269 (5) ◽  
pp. R1060-R1067 ◽  
Author(s):  
T. Raclot ◽  
E. Mioskowski ◽  
A. C. Bach ◽  
R. Groscolas
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Chain Length ◽  
Acid Composition ◽  
Fat Cells ◽  
Adipose Tissues ◽  
Metabolic Feature ◽  
Fatty Acid Mobilization

This study extends our earlier work (T. Raclot and R. Groscolas. J. Lipid Res. 34: 1515-1526, 1993), which showed that, under norepinephrine-stimulated lipolysis, fatty acids of rat retroperitoneal fat cells are selectively mobilized. The present study examines whether this selective mobilization of fatty acids 1) is based on their proportions in adipose tissue, 2) is a metabolic feature common to all adipose tissues, and/or 3) depends on the lipolysis-stimulating agent. Rat fat cells with two markedly different fatty acid compositions were isolated from four white adipose tissues and treated with three lipolytic agents. Fatty acid composition of in vitro released free fatty acids was compared with that of fat cell triacylglycerols, the ratio of percent in free fatty acid to percent in triacylglycerol being defined as the relative mobilization rate (RMR). The RMR of individual fatty acids was related to their molecular structure. It increased exponentially with unsaturation for a given chain length and decreased with increasing chain length for a given unsaturation. The selectivity of fatty acid mobilization was similar regardless of the fatty acid composition of adipose tissue, the tissue location, and the lipolytic agent used. Under conditions of stimulated lipolysis, the selectivity of fatty acid mobilization is therefore a general metabolic feature of adipose tissue. Fatty acids with 16-20 carbon atoms and 4 or 5 double bonds had the highest RMR (from 1.4 to > 5), whereas fatty acids with 20-22 carbon atoms and 0 or 1 double bond had the lowest RMR (from 0.3 to 0.7). For the other fatty acids, RMR was close to unity.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Triacylglycerol biosynthesis in rat adipose-tissue homogenates

1976 ◽  
Vol 159 (3) ◽  
pp. 571-577 ◽  
Author(s):  
W W Christie ◽  
M L Hunter ◽  
R G Vernon
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Oleic Acid ◽  
Linoleic Acid ◽  
Stearic Acid ◽  
Palmitic Acid ◽  
Positional Distribution ◽  
Triacylglycerol Biosynthesis ◽  
Tissue Homogenates ◽  
Rat Adipose Tissue

The optimum cofactor requirements for triacylglycerol biosynthesis in rat adipose-tissue homogenates containing mitochondrial, microsomal and cytosolic fractions were investigated. In general the optimum concentrations of cofactors for triacylglycerol biosynthesis were found to differ from those for total fatty acid esterification. The results provided further evidence for the key role of phosphatidate phosphohydrolase in the regulation of triacylglycerol biosynthesis. Albumin was included in the incubation medium to permit the use of concentrations of added fatty acids that would swamp the effects of endogenous fatty acids. The addition of albumin had little effect on the incorporation of palmitic acid and stearic acid into lipids including triacylglycerols. By contrast, a critical concentration of albumin (about 60 μM) was required before incorporation of oleic acid or linoleic acid into triacylglycerols occurred. The system was used to study the incorporation of different 1-14C-labelled fatty acids from a mixture of unesterified fatty acids [palmitic acid 30%; stearic acid 10%; oleic acid 40%; linoleic acid 20% (molar percentages)] separately into the positions 1,2 and 3 of triacyl-sn-glycerols. In general the stereo-specific distribution of the labelled fatty acids incorporated into triacylglycerols paralleled the normal distribution of fatty acids within rat adipose-tissue triacylglycerols, suggesting that the specificities of the relevant acyltrasferases have the major role in determining the positional distribution of fatty acids within triacylglycerols.

Platelet Aggregation in Finnish Men and Its Relation to Fatty Acids in Platelets, Plasma and Adipose Tissue

1985 ◽  
Vol 54 (03) ◽  
pp. 563-569 ◽  
Author(s):  
M K Salo ◽  
E Vartiainen ◽  
P Puska ◽  
T Nikkari
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Platelet Aggregation ◽  
Acid Composition ◽  
Saturated Fatty Acids ◽  
Free Living ◽  
Ω3 Fatty Acids ◽  
Induced Aggregation

SummaryPlatelet aggregation and its relation to fatty acid composition of platelets, plasma and adipose tissue was determined in 196 randomly selected, free-living, 40-49-year-old men in two regions of Finland (east and southwest) with a nearly twofold difference in the IHD rate.There were no significant east-southwest differences in platelet aggregation induced with ADP, thrombin or epinephrine. ADP-induced platelet secondary aggregation showed significant negative associations with all C20-C22 ω3-fatty acids in platelets (r = -0.26 - -0.40) and with the platelet 20: 5ω3/20: 4ω 6 and ω3/ ω6 ratios, but significant positive correlations with the contents of 18:2 in adipose tissue (r = 0.20) and plasma triglycerides (TG) (r = 0.29). Epinephrine-induced aggregation correlated negatively with 20: 5ω 3 in plasma cholesteryl esters (CE) (r = -0.23) and TG (r = -0.29), and positively with the total percentage of saturated fatty acids in platelets (r = 0.33), but had no significant correlations with any of the ω6-fatty acids. Thrombin-induced aggregation correlated negatively with the ω3/6ω ratio in adipose tissue (r = -0.25) and the 20: 3ω6/20: 4ω 6 ratio in plasma CE (r = -0.27) and free fatty acids (FFA) (r = -0.23), and positively with adipose tissue 18:2 (r = 0.23) and 20:4ω6 (r = 0.22) in plasma phospholipids (PL).The percentages of prostanoid precursors in platelet lipids, i. e. 20: 3ω 6, 20: 4ω 6 and 20 :5ω 3, correlated best with the same fatty acids in plasma CE (r = 0.32 - 0.77) and PL (r = 0.28 - 0.74). Platelet 20: 5ω 3 had highly significant negative correlations with the percentage of 18:2 in adipose tissue and all plasma lipid fractions (r = -0.35 - -0.44).These results suggest that, among a free-living population, relatively small changes in the fatty acid composition of plasma and platelets may be reflected in significant differences in platelet aggregation, and that an increase in linoleate-rich vegetable fat in the diet may not affect platelet function favourably unless it is accompanied by an adequate supply of ω3 fatty acids.

Formation of debranched wheat starch-fatty acid inclusion complexes using saturated fatty acids with different chain length

LWT ◽  
2021 ◽  
pp. 110867
Author(s):  
Min Hyeock Lee ◽  
Ha Ram Kim ◽  
Woo Su Lim ◽  
Min-Cheol Kang ◽  
Hee-Don Choi ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Chain Length ◽  
Inclusion Complexes ◽  
Saturated Fatty Acids ◽  
Wheat Starch
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