Dietary and hormonal effects upon activity of “soluble” protein and particulate fraction of fatty acid desaturation system of rat liver microsomes

Phospholipid desaturase activity of rat liver microsomes can be varied by dietary manipulation: rats starved and refed a "fat-free" diet have two to three times the activity of normal controls whereas starved rats have no detectable activity. These changes were accompanied by changes in fatty acid composition of the microsomal phospholipids, resulting in a double bond:saturated fatty acid mole ratio (moles double bonds per mole saturated fatty acid) of 5.7 in control and starved rats and 4.7 in starved–refed rats. Fluorescence polarization ratio [Formula: see text] of cis- and trans-parinaric acid (PnA) showed no significant differences in physical state of the three microsomal preparations. However, the isolated microsomal phospholipids with trans-PnA as probe showed differences in the temperature at which onset of a change in polarization ratio occurred (starved–refed > normal > starved rats). With the cis-PnA as probe, the polarization ratio showed no change in the range 10–40 °C but was significantly higher (1.8) in starved–refed rats than in normal and starved rats (1.6 in both cases). These data indicate that the microsomal phospholipids of starved–refed animals were in a less fluid state than those from control and starved rats and that this decrease in fluidity was correlated with an increase in phospholipid desaturase activity.

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Nicardipine and Nifedipine Inhibit Fatty Acid Desaturases in Rat Liver Microsomes

Bioscience Biotechnology and Biochemistry ◽

10.1271/bbb.60.1672 ◽

1996 ◽

Vol 60 (10) ◽

pp. 1672-1676 ◽

Cited By ~ 4

Author(s):

Hiroshi Kawashima ◽

Kengo Akimoto ◽

Saeree Jareonkitmongkol ◽

Norifumi Shirasaka ◽

Sakayu Shimizu

Keyword(s):

Fatty Acid ◽

Rat Liver ◽

Liver Microsomes ◽

Rat Liver Microsomes ◽

Fatty Acid Desaturases

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Biosynthetic utilization of photoreactive fatty acids by rat liver microsomes

Canadian Journal of Biochemistry and Cell Biology ◽

10.1139/o84-052 ◽

1984 ◽

Vol 62 (6) ◽

pp. 375-378 ◽

Cited By ~ 6

Author(s):

Pierre Leblanc ◽

Gerhard E. Gerber

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Rat Liver ◽

Alkyl Chain ◽

Liver Microsomes ◽

Rat Liver Microsomes ◽

Phospholipid Synthesis ◽

Derivatives Of

The photoreactive ω-diazirinophenoxy derivatives of nonanoate, undecanoate, tridecanoate, and pentadecanoate were shown to be activated by rat liver microsomes to the corresponding acyl-CoA derivatives. The Km and Vmax for these fatty acid analogues were determined; the values obtained indicate that the addition of a photoreactive group to an alkyl chain has an effect similar to that of elongation of the chain by about seven carbons. Incubation of microsomes in the presence of lysophospholipids resulted in the incorporation of the photoreactive fatty acids into the corresponding phospholipids. The ability of mammalian systems to utilize these photoreactive fatty acids for phospholipid synthesis establishes their suitability as photoaffinity analogues of fatty acids.

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