The Importance of Phospholipid-Protein Interactions for Regulation of the Activities of Membrane-Bound Enzymes

The Effects of Aging on the Hepatic Microsomal Mixed–Function Oxidase System of Male and Female Monkeys

“…This observation has been corroborated in another strain of rat (Sprague-Dawley), as well as in the mouse (36,37). Age-dependent losses of microsoma1 protein and phospholipids in the rat liver have been correlated with concomitant declines in the concentration of smooth-surfaced endoplasmic reticulum membrane (38) and in the catalytic efficiency of MFOS enzymes [e.g., NADPH cytochrome c (P-450) reductase (39)]. However, the absence of similar losses in the monkey liver suggests that aging does not result in reduced hepatic smooth-surfaced endoplasmic reticulum or in a decline in reductase activity.…”

“…The reason(s) for the age-related increase in the in uitro activity of NADPH cytochrome c (P-450) reductase remains unresolved. An increase in the cholesterol/phospholipid ratio may result in reduced membrane fluidity (39). The age-related shifts in the cholesterol/phospholipid ratio correlate well with the changes in the fluidity of the microsomal lipid domain.…”

Determination of phospholipids in soybean (Glycine max (L.) Merr) cultivars by liquid chromatography–tandem mass spectrometry

“…1. Both the polar head groups and fatty acid chains in PLs not only affect the physicochemical properties of the membrane, but also play distinctive roles in biological events (Zakim and Vessey, 1980;Stubbs and Smith, 1984). For example, PI plays a pivotal role in cellular signal transduction (Michell et al, 1988;Fisher et al, 1992;Michell, 1992).…”

The nuclear mutation Ocdts-1 changes the 2-D electrophoretic pattern of Drosophila mitochondria

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In a number of cases abrupt changes in the Arrhenius activation energy of membrane bound enzymes have been suggested to be due to constraints in enzyme movements caused by changes in fluidity of membrane lipids (see, f. inst., review by ZAKIM and VESSEY 1980). In other cases, however, the temperature induced change in activation energy does not follow fluidity changes of the bulk membrane lipids and in these cases changes in the lipids in the vicinity of membrane proteins (boundary lipids, JOST et al 1973;SHIMOMURA, and OZAWA 1981;CHAPMAN et al 1979) are thought to be responsible for changes in activation energy (BERTOLI et al 1976;BUTLER et al 1978).However, also many soluble enzymes show abrupt changes in Arrhenius activation energy (MAS-SEY et al 1966;ADAMS and SWART 1977;HOUGHTON 1979;KABOEV et al 1981).

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