Lipid synthesis in Lipomyces lipofer

1968 ◽  
Vol 46 (4) ◽  
pp. 303-313 ◽  
Author(s):  
F. A. McElroy ◽  
H. B. Stewart
Keyword(s):  
High Speed ◽  
Lipid Synthesis ◽  
Acid Synthesis ◽  
Mitochondrial Fraction ◽  
Maximum Activity ◽  
Rate Limiting Step ◽  
Cell Dispersion ◽  
Lag Period ◽  
Lipomyces Lipofer ◽  
High Speed Supernatant

The synthesis of lipids by cell-free fractions of Lipomyces lipofer was investigated by measuring the incorporation of acetate-14C and other radioactive precursors into lipid-soluble material. On the basis of cofactor requirements, the reaction to inhibitors, and the ability to incorporate appreciable quantities of malonate-14C, it was concluded that the malonyl-CoA pathway was the principal route of fatty acid synthesis in this yeast. By employing a means of cell dispersion less rigorous than previously used with yeasts, it was shown that the soluble portion (high-speed supernatant) of the cell was primarily involved in lipid synthesis. The mitochondrial fraction and the high-speed pellet (96 000 × g, 1 h) were inactive although the latter fraction was required for the maximum activity of the high-speed supernatant. The stimulatory activity of this pellet was very labile and showed a lag period before it became effective. Several lines of evidence suggested that the carboxylation of acetyl-CoA is the rate-limiting step in lipid synthesis which is accelerated by the high-speed pellet.

scholarly journals BRAIN MITOCHONDRIA

1963 ◽  
Vol 19 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Diana S. Beattie ◽  
Howard R. Sloan ◽  
R. E. Basford
Keyword(s):  
High Speed ◽  
Brain Cortex ◽  
Lactate Production ◽  
Mitochondrial Fraction ◽  
Brain Mitochondria ◽  
Glycolytic Enzymes ◽  
Supernatant Fraction ◽  
Glycolytic Activity ◽  
High Speed Supernatant ◽  
Stimulation Of

A mitochondrial fraction prepared from calf brain cortex possessed negligible glycolytic activity in the absence of the enzymes of the high speed supernatant fraction. When mitochondria were added to a supernatant system supplemented with optimal amounts of crystalline hexokinase, a 20 per cent stimulation of glycolysis was observed. The supernatant fraction produced minimal amounts of lactate in the absence of exogenous hexokinase; the addition of mitochondria doubled the lactate production. The substitution of glycolytic intermediates for glucose as substrates as well as the addition of exogenous glycolytic enzymes to the supernatant fraction or supernatant fraction plus mitochondria indicated that the mitochondria contributed mainly hexokinase and phosphofructokinase. By direct assay of all of the enzymes of the glycolytic pathway, only hexokinase and phosphofructokinase were shown to be concentrated in the mitochondrial fraction. All other glycolytic enzymes were found to exhibit higher total and specific activities in the supernatant fraction.

Phosphofructokinase and glycolysis in the livers of rats fed a thrombogenic diet

1970 ◽  
Vol 48 (2) ◽  
pp. 222-224
Author(s):  
N. Simard-Duquesne
Keyword(s):  
Lactic Acid ◽  
High Speed ◽  
Mitochondrial Fraction ◽  
Pasteur Effect ◽  
Phosphofructokinase Activity ◽  
Reconstituted System ◽  
High Speed Supernatant

Liver supernatant phosphofructokinase activity is increased in rats fed a thrombogenic diet at about the same time as the incidence of endotoxin-induced thrombosis is known to increase. In the livers of these rats, the Pasteur effect, as determined by the production of lactic acid in a reconstituted system containing a high-speed supernatant with and without the mitochondrial fraction, is significantly decreased.

Phospholipid metabolism in the molluscs. II. Activities of choline kinase, ethanolamine kinase, and CTP:phosphorylethanolamine cytidyltransferase in the mollusc Helix lactea

1970 ◽  
Vol 48 (5) ◽  
pp. 580-584 ◽  
Author(s):  
Chi-Rong Liang ◽  
M. Segura ◽  
K. P. Strickland
Keyword(s):  
Digestive Gland ◽  
High Speed ◽  
Enzyme Preparation ◽  
Phospholipid Metabolism ◽  
Maximum Activity ◽  
Supernatant Fraction ◽  
Choline Kinase ◽  
Lipid Phosphorus ◽  
Ethanolamine Kinase ◽  
High Speed Supernatant

The distribution of phospholipids in the mollusc Helix lactea was investigated. The results showed that ethanolamine and choline phosphoglycerides are the major phospholipids in this species, amounting to 49% and 26% of the total lipid phosphorus. The amount of ceramide 2-aminoethylphosphonate was 9% of the total phospholipids and this compound was the only phosphonolipid detected in this species. Ethanolamine and choline kinase activities were shown to be present in the high-speed supernatant fraction of snail digestive gland. The maximum activity of choline kinase was found to be higher than that of ethanolamine kinase in the same enzyme preparation. The enzyme CTP:phosphorylethanolamine cytidyltransferase was also demonstrated in the high-speed supernatant fraction of snail digestive gland. The enzymic reaction product was identified as CDP-ethanolamine by paper chromatography and radioautography. The enzymes phosphorylcholine cytidyltransferase and aminoethylphosphonate cytidyltransferase were not detected under the conditions employed in the phosphorylethanolamine cytidyltransferase assays.

scholarly journals Assimilation of glucose carbon in subcellular rat brain particles in vivo and the problems of axoplasmic flow

1967 ◽  
Vol 105 (3) ◽  
pp. 927-936 ◽  
Author(s):  
R. Vrba
Keyword(s):  
Particulate Matter ◽  
High Speed ◽  
Specific Activity ◽  
Sucrose Density Gradient ◽  
Mitochondrial Fraction ◽  
Axoplasmic Flow ◽  
Brain Lipids ◽  
Mitochondrial Fractions ◽  
High Speed Supernatant

1. Rats were injected with [U−14C]glucose and the content of 14C in proteins and lipids of the cerebral P1 (‘nuclear’), P2 (‘mitochondrial’), P3 (‘microsomal’) and high-speed supernatant fractions was measured 7, 22 and 93hr. after injection of labelled glucose. 2. The crude brain mitochondrial fractions (P2) were subfractionated on continuous sucrose gradients (0·32–1·8m-sucrose) and the 14C content of the proteins and lipids of about 20 subfractions was measured. 3. About 40–50% of the 14C assimilated by brain proteins was found in the P2 (‘mitochondrial’) fraction. About 68–70% of the 14C assimilated by brain lipids was also recovered from the lipids of the P2 fraction. 4. Between 22 and 93hr. after injection of [U−14C]glucose both the amount of 14C in the protein of the P2 (‘mitochondrial’) fraction and the specific activity of this protein increased. The specific activity of the protein of all other particulate fractions (P1, P2 and P3) and subfractions (obtained from sucrose-density-gradient subfractionation of fraction P2) when related to the specific activity of the high-speed supernatant protein also increased during 93hr. after injection of [U−14C]glucose. The amount of 14C in the protein of the high-speed supernatant and the specific activity of this protein decreased during the same period. 5. The distribution of 14C in the lipids of all subcellular particulate fractions remained unchanged during the period 22–93hr. after injection of [U−14C]glucose. 6. It was concluded that a diffusion occurs of some supernatant proteins into subcellular particulate matter of the cerebrum and no significant preference for any subcellular particulate matter was observed. The lipids occur in the cerebrum mainly in a non-diffusible state, which is consistent with the view that they form almost entirely a part of the structure of the cerebrum. 7. The data obtained do not lend further support to the concept of axoplasmic flow within the cerebrum or the concept of a one-directional flow of mitochondria or other subcellular particles within the cerebrum.

scholarly journals Species differences in the conjugation of 4-hydroxy-3-methoxyphenylethanol with glucuronic acid and sulphuric acid

1976 ◽  
Vol 158 (1) ◽  
pp. 33-37 ◽  
Author(s):  
K P Wong
Keyword(s):  
Human Liver ◽  
High Speed ◽  
Species Differences ◽  
Glucuronic Acid ◽  
Mitochondrial Fraction ◽  
Mouse Kidney ◽  
Enzyme Preparations ◽  
Guinea Pig Liver ◽  
High Speed Supernatant

The biosynthesis of the glucuronide and sulphate conjugates of 4-hydroxy-3-methoxyphenylethanol was demonstrated in vitro by using the high-speed supernatant and microsomal fractions of liver respectively. These two conjugates were also produced simultaneously by using the post-mitochondrial fraction of rat, rabbit or guinea-pig liver. In contrast only the glucuronide was synthesized by human liver and only the sulphate by mouse and cat livers. Neither of these conjugates was formed by the kidney or the small or large intestine of the rat. A high sulphate-conjugating activity was observed in mouse kidney; the rate of sulphation of 4-hydroxy-3-methoxyphenylethanol with kidney homogenate and high-speed supernatant preparations was 1.8 times greater than with liver preparations. The sulpho-conjugates of 4-hydroxy-3-methoxyphenylethanol and 4-hydroxy-3-methoxy-phenylglycol were also formed by enzyme preparations of rabbit adrenal and rat brain; the glycol was the better substrate in the latter system. Mouse brain did not possess any sulphotransferase activity. For the conjugation of 4-hydroxy-3-methoxyphenylethanol by rabbit liver, the Km for UDP-glucuronic acid was 0.22 mM and that for Na2SO4 was 3.45 mM. The sulphotransferase has a greater affinity for 4-hydroxy-3-methoxyphenyl-ethanol than has glucuronyltransferase, as indicated by their respective Km values of 0.036 and 1.3 mM. It was concluded that sulphate conjugation of 4-hydroxy-3-methoxyphenylethanol predominates in most species of animals.

scholarly journals Detection of CMP-N-acetylneuraminic acid hydroxylase activity in fractionated mouse liver

1989 ◽  
Vol 263 (2) ◽  
pp. 355-363 ◽  
Author(s):  
L Shaw ◽  
R Schauer
Keyword(s):  
Submandibular Gland ◽  
Mouse Liver ◽  
High Speed ◽  
Metal Salts ◽  
Supernatant Fraction ◽  
Inhibitory Influence ◽  
Hydroxylase Activity ◽  
Acetylneuraminic Acid ◽  
Liver Homogenates ◽  
High Speed Supernatant

The finding that N-glycoloylneuraminic acid (Neu5Gc) in pig submandibular gland is synthesized by hydroxylation of the sugar nucleotide CMP-Neu5Ac [Shaw & Schauer (1988) Biol. Chem. Hoppe-Seyler 369, 477-486] prompted us to investigate further the biosynthesis of this sialic acid in mouse liver. Free [14C]Neu5Ac, CMP-[14C]Neu5Ac and [14C]Neu5Ac glycosidically bound by Gal alpha 2-3- and Gal alpha 2-6-GlcNAc beta 1-4 linkages to fetuin were employed as potential substrates in experiments with fractionated mouse liver homogenates. The only substrate to be hydroxylated was the CMP-Neu5Ac glycoside. The product of the reaction was identified by chemical and enzymic methods as CMP-Neu5Gc. All of the CMP-Neu5Ac hydroxylase activity was detected in the high-speed supernatant fraction. The hydroxylase required a reduced nicotinamide nucleotide [NAD(P)H] coenzyme and molecular oxygen for activity. Furthermore, the activity of this enzyme was enhanced by exogenously added Fe2+ or Fe3+ ions, all other metal salts tested having a negligible or inhibitory influence. This hydroxylase is therefore tentatively classified as a monooxygenase. The cofactor requirement and CMP-Neu5Ac substrate specificity are identical to those of the enzyme in high-speed supernatants of pig submandibular gland, suggesting that this is a common route of Neu5Gc biosynthesis. The relevance of these results to the regulation of Neu5Gc expression in sialoglycoconjugates is discussed.

scholarly journals Modulation of lipid-synthesizing enzymes by insulin in differentiated ob17 adipose-like cells

1983 ◽  
Vol 214 (2) ◽  
pp. 443-449 ◽  
Author(s):  
P Grimaldi ◽  
C Forest ◽  
P Poli ◽  
R Negrel ◽  
G Ailhaud
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Specific Activity ◽  
Fatty Acid Synthetase ◽  
Lipid Synthesis ◽  
Acid Synthesis ◽  
Acetate Incorporation ◽  
Long Term Effects ◽  
Response Curves ◽  
Glycerol 3 Phosphate Dehydrogenase

ob17 cells convert into adipose-like cells when maintained in the presence of physiological concentrations of insulin and tri-iodothyronine. After this conversion, insulin removal from differentiated ob17 cells gives within 24-48 h a large decrease in fatty acid synthetase, glycerol 3-phosphate dehydrogenase and acid:CoA ligase activities, as well as in the rate of fatty acid synthesis determined by [14C]acetate incorporation into lipids. All parameters are restored by insulin addition to initial values within 24-48 h. Dose-response curves of insulin on the restoration of glycerol 3-phosphate dehydrogenase activity and of fatty acid synthesis give half-maximally effective concentrations close to 1 nM, in agreement with the affinity for insulin of the insulin receptors previously characterized in these cells. Immunotitration experiments indicate that the changes in the specific activity of fatty acid synthetase are due to parallel changes in the cellular enzyme content. Therefore the ob17 cell line should be a useful model to study the long-term effects of insulin on the modulation of lipid synthesis in adipose cells.

scholarly journals Discrete primary locations of a tyrosine-protein kinase and of three proteins that contain phosphotyrosine in virally transformed chick fibroblasts.

1982 ◽  
Vol 94 (2) ◽  
pp. 287-296 ◽  
Author(s):  
J A Cooper ◽  
T Hunter
Keyword(s):  
Protein Kinase ◽  
High Speed ◽  
Divalent Cations ◽  
Rous Sarcoma ◽  
Nonionic Detergent ◽  
Primary Location ◽  
Hypotonic Buffer ◽  
Tyrosine Protein Kinase ◽  
Sarcoma Virus ◽  
High Speed Supernatant

We have studied the localization of three abundant cellular proteins which are substrates for tyrosine protein kinases in virally transformed chicken embryo fibroblasts. The primary location of each substrate is unaltered by transformation with Rous sarcoma virus (RSV). The tyrosine-phosphorylated species is localized with the nonphosphorylated species. Two of the proteins, of about 46,000 and 28,000 daltons, have a similar location. They are present in the high speed supernatant of cells homogenized in hypotonic buffer, and are soluble in nonionic detergent. The third protein, of about 39,000 daltons, is particulate when cells are homogenized in hypotonic buffer containing divalent cations, but approximately 30% is free in the high-speed supernatant when divalent cations are absent. This protein appears to be associated with the detergent-insoluble matrix when adherent cells are gently lysed in nonionic detergent in situ, but is soluble when the same cells are extracted with nonionic detergent in suspension. This suggests that one of the proteins are tightly associated with detergent-insoluble cytoskeletal structures, unlike the RSV transforming protein itself, which is the main tyrosine protein kinase known to be active in RSV-transformed cells.

scholarly journals Toxic Mechanisms of Aryloxyphenoxypropionates in Target and Non-target Organisms

2019 ◽  
pp. 1-11
Author(s):  
Ayokanmi Ore ◽  
Ebenezer Tunde Olayinka
Keyword(s):  
Membrane Lipids ◽  
Lipid Synthesis ◽  
Oxygen Species ◽  
Acetyl Coa Carboxylase ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Major Toxicity ◽  
Pharmacokinetic Properties ◽  
Entire Plant ◽  
Rate Limiting

Herbicides are substances used to control unwanted plants-weeds. They can be classified into several classes by mechanism of action. This review describes the members of aryloxyphenoxypropionate herbicides, their pharmacokinetic properties, metabolism and their mechanism of phytotoxicity in target weeds as well as in non-target organisms. Two major toxicity mechanisms are described. The first is by inhibition of lipid synthesis. This is achieved by inhibiting the rate limiting step of lipid biosynthesis catalyzed by acetyl CoA carboxylase. The second mechanism is by induction of oxidative stress. This is achieved by generation of reactive oxygen species which in excess can cause oxidative damage to macromolecules and cellular structures especially the membrane lipids. Loss of vital membrane lipids alters the fluidity of membrane, loss of cellular contents and eventually cell death and death of the entire plant.

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