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PubMed1978

Evidence for the existence of a single enzyme catalyzing the phosphorylation of choline and ethanolamine in primate lung.

Choline kinase (ATP:choline phosphotransferase, EC 2.7.1.32) has been isolated and purified 1000-fold from adult African Green monkey lung with a yield of 10%. The purified enzyme also phosphorylated ethanolamine (ratio of ethanolamine kinase to choline kinase = 0.30). This ratio remained constant throughout the purification procedure. The Km for choline (3.0 - 10(-5) M) was lower than that of ethanolamine (1.2 - 10(-3) M.) Choline was also found to inhibit ethanolamine kinase activity by 50% at a concentration of 0.005 mM, while ethanolamine inhibited choline only at very high concentrations (100--150 mM). When the enzyme was subjected to inactivation by heat, hemicholinium-3, trypsin digestion, and p-hydroxymercuribenzoate, both ethanolamine kinase and choline kinase activities were destroyed at the same rate. Freezing and thawing in the absence of glycerol also destroyed both activities at the same rate. Based on these findings, we conclude that in adult African Green monkey lung tissue, there is only one enzyme for the phosphorylation of ethanolamine and choline, and that choline phosphorylation predominates.

Animals↗

PubMed1977

Lecithin consumption raises serum-free-choline levels.

Consumption of choline by rats sequentially increases serum-choline, brain-choline, and brain-acetylcholine concentrations. In man consumption of choline increases in levels in the serum and cerebrospinal fluid; its administration is an effective way of treating tardive dyskinesia. We found that oral lecithin is considerably more effective in raising human serum-choline levels than an equivalent quantity of choline chloride. 30 minutes after ingestion of choline chloride (2-3 g free base), serum-choline levels rose by 86% and returned to normal values within 4 hours; 1 hour after lecithin ingestion, these levels rose by 265% and remained significantly raised for 12 hours. Lecithin may therefore be the method of choice for accelerating acetylcholine synthesis by increasing the availability of choline, its precursor in the blood.

Acetylcholine↗

PubMed1977

Choline kinase and ethanolamine kinase are separate, soluble enzymes in rat liver.

Choline kinase and ethanolamine kinase are located in the cytosol from rat liver and have been copurified more than 500-fold by affinity chromatography [P. J. Brophy and D. E. Vance (1976) FEBS Lett. 62, 123-125]. Kinetic properties of the two activities were determined. Choline kinase had a Km for choline of 0.033 mM and ethanolamine was a competitive inhibitor (Ki = 6.2 mM). Ethanolamine kinase had a Km for ethanolamine of 7.7 mM and choline was a 'mixed' type of inhibitor with a Ki of 0.037 mM. Both enzymes activities responded in a similar fashion to the adenylate energy charge. Betaine and choline phosphate partially inhibited both kinases with a 93% inhibition of the ethanolamine kinase by 5 mM choline phosphate. CTP and ethanolaminephosphate partially inhibited the ethanolamine kinase, but not the choline kinase. Other metabolites tested had negliglible effects on both kinases. The affinity-column-purified enzyme was analyzed by disc gel electrophoresis which resolved the two activities. Hence, although many of the properties of the two activities are similar, choline kinase and ethanolamine kinase must be separate enzymes. Analysis of rat liver cytosol by disc gel electrophoresis indicated four isoenzymes for choline kinase and ethanolamine kinase.

Adenine Nucleotides↗

PubMed1979

Ethanolamine kinase activity and compositions of diacylglycerols, phosphatidylcholines and phosphatidylethanolamines in livers of choline-deficient rats.

These experiments were performed to find the reasons for the increased concentrations of docosahexaenoyl phosphatidylethanolamines (PE) in livers of choline-deficient rats. We measured the activity of ethanolamine kinase, which catalyzes the first step in PE formation. We also measured the compositions of PE and phosphatidylcholines (PC) and concentrations and fatty acid compositions of diacylglycerols (DG), which are precursors of PE. Young male rats were fed for one week a low-methionine, choline-deficient diet, or the same diet supplemented with choline. Ethanolamine kinase activity was measured in liver cytosol (100,000 g supernatant). Fatty acids were measured in total liver diacylglycerols and in microsomal PE and PC. Ethanolamine kinase activities were equal in choline-deficient and choline-supplemented rats. Concentrations of DG were elevated 6-fold by choline deficiency. The percentage of docosahexaenoic acid (22:6n-3) in microsomal PE was nearly doubled by choline deficiency. Although the increased concentrations of PE in choline-deficient livers cannot be attributed to increased activity of ethanolamine kinase, the rate of PE formation probably was increased by increases in concentrations of its precursors, including DG. The disproportionate increase in 22:6n-3 PE probably was caused by a selective formation of PE from DG that contain 22:6n-3.

Animals↗

PubMed1975

Intestinal absorption of cytidine diphosphate choline and its changes in the digestive tract.

Intestinal absorption of cytidine diphosphate choline (CDP-choline), its structural changes in the digestive tract, and hepatic uptake have been investigated in rats using 14C-labeled (14CH3 attached to N of choline) and 3H-labeled (at C5 of pyrimidine) compounds. The results indicate that: 1)CDP-choline is relatively stable in the stomach, but is quickly degraded into cytidine and choline in the intestine; 2) The hepatic uptakes of 14C and 3H reach the maximum in two to three hours after oral administration; 3) Whereas the amount of 14C remaining in the gut is inversely related to the hepatic uptake, no similar correlation is seen with 3H-labeled CDP-choline, and 4) Extrahepatic uptake of 14C and 3H is very small. The possibility of phosphorylation in the mucosa of choline and cytidine has been discussed, based on the differences in individual broken-down products in the intestinal lumen and mucosa.

Animals↗

PubMed1975

Lipd profiles of plasma lipoproteins of fasted and fed normal and choline-deficient rats.

Three major density classes of lipoproteins and a residual protein (d greater than 1.21) were isolated by ultracentrifugation from plasma of fasted, fed normal, and choline-deficient rats. Lipid extracts were obtained from total plasma and the various density classes of lipoproteins, and each extract was examined in detail by thin layer and gas chromatographies. The results indicated essentially identical compositions of molecular species of phosphatidyl choline, which suggested their rapid equilibration among the different plasma lipoprotein classes. In contrast, the molecular species of the triacylglycerols and cholesteryl esters showed significant differences among the chylomicrons, very low and low, and high density lipoproteins, which excluded the possibility of their ready equilibration in vivo. Omission of choline from diet resulted in a sharp and statistically significant decrease in all lipid components of the very low and low density lipoproteins with 2 days. After 10 days of choline deficiency, the lipid levels of chylomicrons and very low and low density lipoproteins were ca. one-half the levels found in the choline supplemented animals, and there were discernible distortions in their lipid composition. Reintroduction of choline led to a prompt return to normal levels and lipid composition of both chylomicron and very low and low density lipoprotein fractions. The lack of equilibration of the triacylglycerols among the lipoprotein classes under normal conditions and in choline deficiency demonstrates an as yet unrecgnized source of compartmentation of plasma lipids.

Body Weight↗

PubMed2026

Gut bacteria associated with an atherogenic TMAO-dietary pattern and choline-rich foods among aging women.

BACKGROUND AND AIMS: Choline can be metabolized by gut bacteria with a choline utilization gene, CutC, as identified through genome sequencing studies. This metabolism produces trimethylamine, the precursor to the atherosclerotic metabolite trimethylamine N-oxide (TMAO). Bacterial species involved in trimethylamine production in free-living humans have been under-investigated. We previously developed the TMAO dietary pattern (TMAO-DP), which is predictive of plasma TMAO and choline. We evaluated associations between the TMAO-DP, dietary choline, and choline-rich foods (fish, red meat, eggs) with the abundance of species with CutC. We also explored associations between the TMAO-DP and microbiome diversity. METHODS AND RESULTS: This cross-sectional analysis included 287 women (mean age = 79.6 years) from the Women's Health Initiative. Diet was assessed using a food frequency questionnaire. Stool samples were collected and the V3-V4 regions of the 16S ribosomal RNA were sequenced. Adjusted linear regression models evaluated associations between the TMAO-DP with the CLR-transformed abundance of species with CutC and with alpha-diversity indices. For beta-diversity, PERMANOVA examined measures of Aitchison distance within and between quartiles of the TMAO-DP. Associations between dietary choline and choline-rich foods with the abundance of species were evaluated using linear regression. The TMAO-DP was associated with Acidaminococcus intestini [Beta (SE): 0.23 (0.09), p-value = 0.035] and Desulfovibrio desulfuricans [Beta (SE): 0.16 (0.6), p = 0.035]. The TMAO-DP was not associated with alpha- or beta-diversity. CONCLUSION: This study provides evidence that Desulfovibrio desulfuricans and Acidaminococcus intestini, two species identified as having CutC by gene sequencing, may produce trimethylamine from diet in free-living women.

Humans↗

PubMed1978

Histochemical technique to detect choline-containing lipids.

An almost specific and highly sensitive technique to detect histochemically choline-containing lipids is proposed. This technique is based on the effect of Hg++ and phosphomolybdic ion on the choline, that yields insoluble complexes able to react with diphenylcarbazide producing a deep blue or violet stain. The specificity and the sensitivity of this technique was investigated on filter paper strips loaded with choline-containing lipids, choline-free lipids, steroids, vitamins, proteins or choline hydrochloride. The results show that the choline-containing substances react positively. The choline-free substances react negatively except calciferol and vitamin A that show weakly positive results. This technique used on tissue sections appears very suitable to histochemical purposes.

Adrenal Glands↗

PubMed1975

Viral stimulation of choline phosphotransferase in spleen microsomes.

Choline phosphotransferase and phosphatidyl ethanolamine methyltransferase enzymatic activities (nmoles phosphatidyl choline/min/mg protein) have been determined in spleen microsomes of Rauscher virus infected balb/c male mice at 5, 10, 14, and 21 days following inoculation of the virus. There is a significant stimulation of the choline phosphotransferase activity in the virus infected spleens with the peak of activity at about 10 days of viral infection. The specific activity of choline phosphotransferase is 10 times that of the phosphatidyl ethanolamine methyltransferase at 10 days of viral infection. There is a 51-fold increase over controls for the total microsomal choline phosphotransferase at 14 days of viral infection and only an 18-fold increase over controls for the phosphatidyl ethanolamine methyltransferase activity. There is a significant (P less than 0.001) increase over controls in the concentration of total phospholipid-P, phosphatidyl choline-P, and phosphatidyl choline-P fractions as separated by argentation chromatography of microsomes from spleens of mice infected with Friend virus of Rauscher virus for 14 days. The choline phosphotransferase and phosphatidyl ethanolamine methyltransferase specific activities in liver microsomes of 14 day Friend and/or Rauscher virus are unaltered during viral infection.

Animals↗

PubMed1978

Effect of isoprenaline on salivary gland lipids of rats fed a choline-deficient diet.

Male adult rats were fed choline deficient and a choline-supplemented diet for 3 weeks. Half the rats from each group were injected with isoprenaline (16 mg/kg body weight) and the remainder with saline. After 2 and 8 hours, rats were sacrificed, their submandibular salivary glands were disected out, and extracted for lipids. The fatty acid composition of total lipids and some neutral and phospholipid fractions were determined. Isoprenaline administration resulted in a slightly higher level of oleic acid in SMSG of rats fed choline-deficient but not the control diet. There was an increase in the free fatty acid (FFA) concentrations of the gland after 2 hours of isoprenaline treatment in rats fed the control diet; no such increase was observed in the choline-deficient group. The fatty acid composition of FFA fraction was also slightly changed as a result of isoprenaline treatment, but only in the choline-deficient group. The fatty acid composition of triglyceride (TG), phosphatidyl choline (PC), and phosphatidyl ethanolamine (PE) fractions was not changed.

Animals↗

PubMed1978

Effects of dietary choline and N,N-dimethylaminoethanol on lung phospholipid and surfactant of newborn rats.

Pups delivered by rats fed during pregnancy a choline-deficient (CD) diet containing 1% N,N-dimethylaminoethanol (DME) die within 36 hr of birth. The concentrations of sphingomyelins, phosphatidyl cholines, and disaturated phosphatidyl cholines in the lungs of these pups are lower than those in the lungs of pups delivered by dams fed a choline-supplemented diet (CS). The amount of surfactant isolated from the lung of the pups was also reduced. These changes were accompanied by alterations in the activity of enzymes (choline kinase, EC 2.7.1.32; choline phosphotransferase, EC 2.7.8.2) involved in the synthesis of lung lecithins. These results strongly suggest that pups delivered by dams fed a CD diet containg 1% DME die of respiratory distress syndrome due to altered metabolism of lung surfactant.

Animals↗

PubMed1977

Effects of deoxycholate and phospholipase A2 on choline and ethanolamine phosphotransferases of chicken brain microsomes.

Ethanolamine phosphotransferase (EC 2.7.8.1) and choline phosphotransferase (EC 2.7.8.2) activities were assayed in fresh microsomes from adult chicken brains with either diacylglycerols or alkylacylglycerols. Pretreatment of microsomes with 1.25 mM sodium deoxycholate, a concentration less than the critical micelle concentration, produced a slight inhibition of choline phosphotransferase activity. A deoxycholate concentration (5.0 mM) greater than the critical micelle concentration (3.0 mM) decreased the choline phosphotransferase activity by more than 70% but had no effect on ethanolamine phosphotransferase activity. Inclusion of 1.25 mM deoxycholate in the assay medium decreased choline phosphotransferase activity 35% but increased ethanolamine phosphotransferase activity 50%. The deoxycholate appeared to inactive the choline phosphotransferase. Phospholipase A2 (Vipera russelli) treatments of microsomes removed phosphoglycerides and decreased both phosphotransferase activities to a similar extent. Decreased activities are probably due to disruption of the membrane structure. Choline and ethanolamine phosphotransferase activities are apparently in different enzymes which lack specificity for the type of diglyceride. Thus, the systematic names should include 1,2-diradyl-sn-glycerol instead of 1,2-diacyl-sn-glycerol.

Animals↗

PubMed1976

The uptake of choline by rat liver mitochondria.

1. Rat liver mitochondria can accumulate choline against a concentration gradient. Maximally about 30 nmol choline per mg mitochondrial protein are found in the matrix space. 2. The process of choline uptake is biphasic. After a rapid uptake of 1.5-15 nmol per mg protein, a slower uptake occurs if an energy supply is present. In the absence of energy, only the rapid uptake is found. 3. The inhibition of uncoupler-stimulated choline oxidation by cations is the result of an inhibition of choline uptake.

Adenosine Triphosphate↗

PubMed1979

Asymmetry of the site of choline incorporation into phosphatidylcholine of rat liver microsomes.

[14C]Choline was incorporated into microsomal membranes in vivo, and from CDP-[14C]choline in vitro, and the site of incorporation determined by hydrolysis of the outer leaflet of the membrane bilayer using phospholipase C from Clostridium welchii. Labelled phosphatidylcholine was found to be concentrated in the outer leaflet of the membrane bilayer with a specific activity approximately three times that of the inner leaflet. During incorporation of CDP-choline and treatment with phospholipase C the vesicles retained labelled-protein contents indicating that they remained intact. When the microsomes were opened with taurocholate after incorporation of [14C]choline in vivo, the labelled phosphatidylcholine behaved as a single pool. Selective hydrolysis of labelled phosphatidylcholine in intact vesicles is not, therefore, a consequence of specificity of phospholipase C. These results indicate that the phosphatidylcholine of the outer leaflet of the microsomal membrane bilayer is preferentially labelled by the choline-phosphotransferase pathway and that this pool of phospholipid does not equilibrate with that of the inner leaflet.

Animals↗

PubMed1978

The uptake of choline by Streptococcus pneumoniae.

Uptake of choline, a structural component of pneumococcal C- and F-teichoic acids, into bacteria growing in a defined medium was very efficient with an uptake constant ([S]10 5) of 3.2 microns. It was inhibited by iodoacetate, dinitrophenol and oligomycin but not by structural analogues of choline. Ethanolamine, however, was transported in the absence of choline but with a reduced affinity ([S]0.5 71.4 microns). The same constitutive system was probably used by both ethanolamine and choline. It is suggested that this system required ATP and probably involved choline kinase.

Antimetabolites↗

PubMed1975

Specific recognition of choline residues in the cell wall teichoic acid by the N-acetylmuramyl-L-alanine amidase of Pneumococcus.

Pneumococci growing on choline-containing medium are known to incorporate this amino alcohol into the wall teichoic acid and produce autolysin-sensitive cell walls. In contrast, bacteria grown on the choline analogue, ethanolamine, incorporate ethanolamine into the teichoic acid and synthesize cell walls that are resistant to the homologous autolysin. In this communication, we report experiments aimed at understanding the biochemical mechanism of this phenomenon. Ethanolamine-containing (autolysin-resistant) cell walls were methylated in vitro with methyl iodide. Under appropriate conditions, virtually all of the ethanolamine residues could be converted to choline. After methylation, the formerly autolysin-resistant walls could be quantitatively hydrolyzed by the pneumococcal autolysin. Methylated walls also recovered another property typical of cell walls isolated from choline-grown bacteria: they could induce the in vitro "conversion" of an inactive form of autolysin to the catalytically active form (Tomasz, A., and Westphal, M. (1971) Proc. Natl. Acad. Sci. U.S.A. 68, 2627-2630). The results suggest that the autolysin-catalyzed hydrolysis of amide bonds in the peptidoglycan requires an additional interaction between the enzyme protein and choline residues in the teichoric acid portion of the cell wall.

Alanine↗

PubMed1978

Enhancement by choline of the induction of adrenal tyrosine hydroxylase by phenoxybenzamine, 6-hydroxydopamine, insulin or exposure to cold.

Treatments that increase the release of acetylcholine from the splanchnic nerve have previously been shown to induce the enzyme tyrosine hydroxylase in adrenal chromaffin cells. Such treatments include the systemic administration of the drugs phenoxybenzamine and 6-hydroxydopamine, insulin-induced hypoglycemia, and prolonged exposure to cold. We have reported that the administration of choline also induces the adrenal enzyme and have suggested that the mechanism of this induction involves an increase in the amount of acetylcholine released each time the splanchnic nerve fires. In the present studies, rats received both choline and one of the above treatments. Choline caused an augmentation of the adrenomedullary response to each of the treatments, but it had no apparent effect on a presynaptic enzyme, choline acetyltransferase. These observations strongly support the view that choline availability determines both the amount of acetylcholine present in nerve terminals and the amount liberated when cholinergic neurons fire.

Acetylcholine↗

PubMed1977

The biosynthesis of a choline nucleotide by a cell-free extract from Streptococcus pneumoniae.

Choline, a component of the wall teichoic acid of Streptococcus pneumoniae, was converted to cytidine diphosphocholine via choline phosphate by enzymes which were identified in cell-free extracts of the pneumococcus. The first enzyme, choline kinase, was investigated in some detail. It appeared to have a pH optimum of 7.3 to 7.4 and was stimulated by Mg2+. Kinetic studies gave an apparent Michaelis constant (Km) for ATP of I mM, and for choline of 0.19 mM, with Vmax values of 3 nmol min-1 (mg protein)-1 and 0.5 nmol min-1 (mg protein)-1 respectively. The second enzyme, CDPcholine pyrophosphorylase was specific for CTP and had a requirement for Mg2+ with an optimum at 7 mM.

Cell-Free System↗