scholarly journals Δ5-desaturase activity in liver and brain microsomes during development of the pig

1985 ◽  
Vol 227 (3) ◽  
pp. 1021-1023 ◽  
Author(s):  
M T Clandinin ◽  
K Wong ◽  
R R Hacker
Keyword(s):  
Brain Tissue ◽  
Early Development ◽  
Desaturase Activity ◽  
Microsomal Protein ◽  
Chain Elongation ◽  
Perinatal Development ◽  
Δ5 Desaturase ◽  
Metabolic Capability ◽  
Brain Microsomes ◽  
Delta 5 Desaturase

Microsomes isolated from liver and brain tissue were assayed to examine transitions in metabolic capability to synthesize tetraenes and pentaenes by chain elongation-desaturation of C20:3(8,11,14) during the perinatal development of the pig. Rates of synthesis of tetraenes and pentaenes by chain elongation-desaturation of C20:3(8,11,14) were greatest in liver. During the latter half of gestation, the capability to synthesize tetraenes increased 7- or 23-fold on a per mg of microsomal protein basis for brain and liver respectively. Increase in the capacity to synthesize tetraenes from C20:3(8,11,14) suggests a significant transition in the activity of the delta 5-desaturase during the last half of gestation. These observations indicate that in liver and brain the capability to chain elongate-desaturate C18:2(9,12) to longer chain homologues increases significantly during early development as a function of transitions in the activity of the delta 5-desaturase.

scholarly journals Synthesis of chain elongation-desaturation products of linoleic acid by liver and brain microsomes during development of the pig

1985 ◽  
Vol 226 (1) ◽  
pp. 305-309 ◽  
Author(s):  
M T Clandinin ◽  
K Wong ◽  
R R Hacker
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Brain Tissue ◽  
Fetal Liver ◽  
Microsomal Protein ◽  
Chain Elongation ◽  
Metabolic Capability ◽  
Brain Microsomes ◽  
Delta 5 Desaturase ◽  
Long Chain

Microsomes isolated from liver and brain tissue were assayed to examine transitions in metabolic capability to synthesize chain elongation-desaturation products of C18:2(9,12) during the perinatal development of the pig. Microsomal synthesis of trienes, tetraenes and pentaenes was compared for fetal, neonatal and postnatal piglets. Rates of synthesis of tetraenes and pentaenes by chain elongation-desaturation of C18:2(9,12) were greatest in liver. During the later half of gestation, the capability to synthesize tetraenes increased 2-3-fold on a per mg of microsomal protein basis. Increase in the capacity to synthesize tetraenes suggests a significant transition in the activity of delta 5 desaturase during the last half of gestation. For brain, synthesis of C22:5(4,7,10,13,16) from C18:2(9,12) was greatest at term. These observations indicate that in liver and brain the capability to chain elongate-desaturate C18:2(9,12) to longer chain homologues increases significantly during early development. It is suggested that during gestation the activity of the delta 5 desaturase limits synthesis of C20 and C22 homologues of C18:2(9,12). The metabolic conversion of C20 and C22 fatty acids by chain elongation of C20:4(5,8,11,14) does not appear to limit the synthesis of very long chain homologues of linoleic acid in fetal liver or brain.

scholarly journals Alternative route for the biosynthesis of polyunsaturated fatty acids in K562 cells

1993 ◽  
Vol 291 (3) ◽  
pp. 841-845 ◽  
Author(s):  
J Naval ◽  
M J Martínez-Lorenzo ◽  
I Marzo ◽  
P Desportes ◽  
A Piñeiro
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Desaturase Activity ◽  
Alternative Pathway ◽  
K562 Cells ◽  
Chain Elongation ◽  
Pufa Biosynthesis ◽  
Delta 5 Desaturase ◽  
Delta 9 Desaturase ◽  
Delta 6 Desaturase

K562 human leukaemia cells lack a significant delta 6-desaturase activity. However, they synthesize long-chain polyunsaturated fatty acids (PUFA) from linoleic (C18:2(9,12)) and linolenic (C18:3(9,12,15)) acids, by reactions involving a C2 chain elongation followed by a delta 5-desaturation step and, to some extent, a further elongation. The main products formed were separated by argentation t.l.c. and identified by g.l.c. as the uncommon fatty acids C20:3(5,11,14) and C20:4(5,11,14,17) respectively. These acids were also produced when cells were supplemented with C20:2(11,14) or C20:3(11,14,17) respectively. The presence of a delta 5-desaturase was further confirmed by using its corresponding normal substrates, C20:3(8,11,14) and C20:4(8,11,14,17), which led to C20:4(5,8,11,14) and C20:5(5,8,11,14,17) respectively. On the other hand, a high delta 9-desaturase activity, but no significant delta 4-desaturase activity, were detected in K562 cells. These results indicate the existence of an alternative pathway, involving delta 5-desaturase, which is the only route for PUFA biosynthesis in K562 cells. This pathway may be relevant for the biosynthesis of PUFA in cells lacking delta 6-desaturase activity.

scholarly journals Neurosteroid metabolism. 7α-Hydroxylation of dehydroepiandrosterone and pregnenolone by rat brain microsomes

1992 ◽  
Vol 288 (3) ◽  
pp. 959-964 ◽  
Author(s):  
Y Akwa ◽  
R F Morfin ◽  
P Robel ◽  
E E Baulieu
Keyword(s):  
Rat Brain ◽  
Microsomal Protein ◽  
Optimal Conditions ◽  
Hydroxylated Metabolites ◽  
Enzymic Reaction ◽  
Polar Metabolites ◽  
Brain Microsomes ◽  
Prepubertal Rats ◽  
Derivatives Of

Two ‘neurosteroids’, dehydroepiandrosterone (DHEA) and pregnenolone (PREG), are converted by rat brain microsomes into polar metabolites, identified as the respective 7 alpha-hydroxylated (7 alpha-OH) derivatives by the ‘twin ion’ technique of g.l.c.-m.s. with deuterated substrates. The enzymic reaction requires NADPH and is stimulated 2-4-fold by EDTA. Under optimal conditions (pH 7.4, 0.5 mM-NADPH, 1 mM-EDTA), the Km values for DHEA and PREG are 13.8 and 4.4 microM respectively, and the Vmax. values are 322 and 38.8 pmol/min per mg of microsomal protein respectively. Trace amounts of putative 7 beta-OH derivatives of DHEA and PREG are detected. Oestradiol, at a pharmacological concentration of 5 microM, inhibits DHEA and PREG 7 alpha-hydroxylation. Formation of 7 alpha-hydroxylated metabolites is low in prepubertal rats and increases 5-fold in adults. Derivatives of PREG and DHEA, such as PREG sulphate, DHEA sulphate, progesterone and 3 alpha-hydroxy-5 alpha-pregnan-20-one, are known to be neuroactive. Therefore the quantitatively important metabolism to 7 alpha-OH compounds may contribute to the control of neurosteroid activity in brain.

Microsomal Protein Mediates a pH-Dependent Fusion of Liposomes to Rat Brain Microsomes

1990 ◽  
Vol 9 (4) ◽  
pp. 253-261 ◽  
Author(s):  
Roberto Pistolesi ◽  
Lanfranco Corazzi ◽  
Giuseppe Arienti
Keyword(s):  
Rat Brain ◽  
Microsomal Protein ◽  
Brain Microsomes ◽  
Ph Dependent

Plasma polyunsaturated fatty acid profile and delta-5 desaturase activity are altered in patients with type 2 diabetes

Metabolism ◽  
2014 ◽  
Vol 63 (11) ◽  
pp. 1432-1438 ◽  
Author(s):  
Satoshi Imamura ◽  
Tomoaki Morioka ◽  
Yuko Yamazaki ◽  
Ryutaro Numaguchi ◽  
Hiromi Urata ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Polyunsaturated Fatty Acid ◽  
Desaturase Activity ◽  
Delta 5 Desaturase

scholarly journals High activity of cytochrome P-450-linked aminopyrine N-demethylase in mouse brain microsomes, and associated sex-related difference

1989 ◽  
Vol 261 (3) ◽  
pp. 769-773 ◽  
Author(s):  
V Ravindranath ◽  
H K Ananda Theertha Varada
Keyword(s):  
Mouse Brain ◽  
Male Mouse ◽  
Mouse Liver ◽  
Double Diffusion ◽  
Microsomal Protein ◽  
Cross Reactivity ◽  
Related Difference ◽  
Brain Microsomes ◽  
Demethylase Activity ◽  
Cytochrome P 450

The presence of cytochrome P-450 and associated mono-oxygenase activities was examined in brain microsomes from male and female mice. Although the cytochrome P-450 level in male mouse brain was very low as compared with mouse liver, the aminopyrine N-demethylase and morphine N-demethylase specific activities in male mouse brain were much higher than those observed in mouse liver. Ethoxycoumarin O-de-ethylase and aniline hydroxylase activities were, however, not detected in mouse brain. Sex-related differences were observed in both the cytochrome P-450 levels and aminopyrine N-demethylase activity in mouse brain, the levels of both being higher in male mouse brain as compared with female mouse brain. Aminopyrine N-demethylase activity in mouse brain microsomes was dependent on the presence of oxygen and NADPH and could be inhibited by piperonyl butoxide, N-octyl imidazole and carbon monoxide. Antiserum raised to the phenobarbital-inducible form of rat liver cytochrome P-450 [P-450(b+e)] inhibited mouse brain aminopyrine N-demethylase activity by around 80+ mouse brain microsomal protein exhibited cross-reactivity against this antiserum when examined by Ouchterlony double diffusion and immunoblotting. The present results indicate the presence of a phenobarbital-inducible form of cytochrome P-450 (or a form of cytochrome P-450 that is similar immunologically) in mouse brain microsomes, which is associated with a sex-related difference.

scholarly journals Effect of dietary fats on the δ6- and δ5-desaturation of fatty acids in rat liver microsomes

1983 ◽  
Vol 50 (3) ◽  
pp. 749-756 ◽  
Author(s):  
D. Kirstein ◽  
C.-E. Høy ◽  
G. Hølmer
Keyword(s):  
Arachidonic Acid ◽  
Linolenic Acid ◽  
Rat Liver ◽  
Desaturase Activity ◽  
Liver Microsomes ◽  
Dietary Fats ◽  
Rat Liver Microsomes ◽  
Δ5 Desaturase ◽  
Substrate Level

1. Rats were given diets containing (% dietary energy): 46 arachis oil (AO), 36 partially-hydrogenated arachis oil (HAO) + 10 AO, 36 partially-hydrogenated marine oil (HMO) + 10 AO, or 46 of a combination of rape-seed oils high and low in erucic acid (RSO + LERSO).2. In the liver microsomes the content of arachidonic acid (20:4ω6) was reduced inthe groups given HAO + AO and HMO + AO.3. The rates of Δ6-desaturation of linoleic acid into γ-linolenic acid (18:3ω6) and of Δ5-desaturation of dihomo-γ-linolenic acid into arachidonic acid were studied in vitro at two substrate levels: a high substrate level reflecting maximal microsomal desaturase activity in rat liver and a low substrate level reflecting desaturase activity under physiological conditions.4. Dietary HAO, rich in 18:1 isomers, suppressed the Δ6-desaturase activity butnot the Δ5-desaturase activity. Dietary HMO, rich in 18:1, 20:1 and 22:1 isomers, reduced both Δ6- and Δ5-desaturase activities.

scholarly journals Hepatic ∆6-desaturase activity in lean and genetically obese ob/ob mice

1985 ◽  
Vol 225 (2) ◽  
pp. 307-313 ◽  
Author(s):  
S Hughes ◽  
D A York
Keyword(s):  
Food Intake ◽  
Cold Acclimation ◽  
Desaturase Activity ◽  
Mitochondrial Fraction ◽  
Obese Mice ◽  
Delta 5 Desaturase ◽  
Delta 6 Desaturase

Hepatic delta 6-desaturase activity is primarily located in the mitochondrial fraction in mice. Both delta 6- and delta 5-desaturase activities are increased in the liver of young (6-week-old) obese mice. The increase in hepatic delta 6-desaturase activity in obese mice does not occur until weaning. Neither restriction of food intake nor hyperinsulinaemia normalize hepatic delta 6-desaturase activity of obese mice. Both cold acclimation and tri-iodothyronine (30 micrograms/day per kg) decreased hepatic delta 6-desaturase activity of obese mice to levels observed in lean mice, whereas the increase in activity in obese mice was still maintained after the induction of hypothyroidism.

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