The effect of acyl-group composition on the rate of acyltransferase-catalyzed synthesis of lecithin

Abstract

The acyltransferase rates for 66 combinations of substrates (6 acylglycerolphosphorylcholines and II acylcoenzyme A derivatives) were measured using an enzyme preparation from pig liver. The results support the earlier findings with ratliver enzymes showing that the position to be acylated was more significant than the composition of fatty acids in the I-acylglycerolphosphorylcholine. EXPERIMENTAL Preparation of lecithin from egg yolkEgg yolk (8 kg obtained from University of Michigan Food Service) was homogenized with 48 1 of acetone (technical grade). The homogenate was filtered and the ~-

Fatty acid metabolism during hypothermic perfusion of the isolated dog kidney

“…In favour of the latter mechanism is that acylCoA : lysolecithin acyl-transferase preferentially reincorporates unsaturated fatty acids [ 141, and that acyl-CoA hydrolase is more active with short-chain unsaturated fatty acids [14]. The chainlength of the fatty acid may also be of importance for the reincorporation, since arachidonic acid is incorporated more rapidly than oleic acid by this mechanism [4].…”

Properties of partially purified liver microsomal cytochrome P‐450: Acceptance of two electrons during anaerobic titration

“…Total iron and copper were estimated by atomic absorption spectrophotometry and FMN and FAD by the procedure of King [ 18]. Dilauroylglyceryl-3-phosphorylcholine was synthesized by a published procedure [19] and sonicated before use. Highly purified cytochrome P-450ca m was kindly provided by Dr. I.C.…”

An enhanced incorporation of fatty acid into phosphatidyl choline that parallels histamine discharge in mast cells

“…From the percentage distribution (% label) figures, it is evident that A23187 treatment leads to little, if any, significant change in the positional labeling of PA with either fatty acid whereas PC exhibits a slight enhancement in B-position labeling by linoleate and a dramatically enhanced incorporation into this position with palmitate. In the case of linoleate, increased B-position labeling of PC would be expected regardless of whether the stimulation mechanism entailed selective acylation or amplification of de novo synthesis [1,8,63]. However, the major shift in distribution for PC labeling observed using palmitate indicates, first, that the ionophore-enhanced incorporation strongly favors the B-position and, second, that the putative acyl transferase appears to use the most abundant substrate [8].…”

“…In the case of linoleate, increased B-position labeling of PC would be expected regardless of whether the stimulation mechanism entailed selective acylation or amplification of de novo synthesis [1,8,63]. However, the major shift in distribution for PC labeling observed using palmitate indicates, first, that the ionophore-enhanced incorporation strongly favors the B-position and, second, that the putative acyl transferase appears to use the most abundant substrate [8]. The stimulated/control labeling ratios for lysophosphatide and fatty acid shown in Table 1 support these observations, since for PC DPM stimulated FFA DPM stimulated LPC > DPM control FFA DPM control LPC and further illustrate two additional features of the labeling process.…”