Activation of alkyldihydroxyacetone phosphate synthase by detergents

“…Several enzymes, particularly those that are membrane bound, are stimulated by surfactant substances. In some cases, such as glucose-6- Arion et al, 1976) and alkylglycerophosphate acyltransferase (EC 2.3.1.63; Rock et al, 1977), the detergent removes a membrane barrier that separates the enzyme from its substrate. With other enzymes that act upon lipids, such as phospholipases (Upreti and Jain, 1978) and sphingolipid hydrolases (Sandhoff and Conzelmann, 1979), the role of detergent often is to modify the physical properties of these substrates, causing them to be more susceptible to the enzyme.…”

Section: Amentioning

confidence: 99%

Fatty Acid Activation and Temperature Perturbation of Rat Brain Microsomal Phospholipase D

Chalifour

Kanfer

1982

Journal of Neurochemistry

121

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The hydrolytic and transphosphatidylation activities of rat brain microsomal phospholipase D were highly latent in the absence of an appropriate activator. The most suitable surfactants for this activation were oleate and palmitoleate. Besides the bile acids and unsaturated fatty acids, other naturally occurring surfactants, such as lysophospholipids, acidic phospholipids, acyl-CoA's, and gangliosides, were inactive. Taurodeoxycholate, at optimal concentration, produced a profound inhibition of oleate activation. Phospholipase D activity was detectable in all rat tissues investigated. The optimal incubation temperature for phospholipase D was 30 degrees C, with a break point at 16.1 degrees C in an Arrhenius plot.

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“…We have shown that this is correct, but that it is not the substrate DHAP or the product acyl-DHAP, but palmitoyl-CoA which is prevented from dephosphorylation in the presence of fluoride. The topographical distribution of the DHAP-AT [2,15,17,34] and the alkyl-DHAP synthase [34,40] have also been studied before. Rock et al concluded that both the DHAP-AT [15] and the alkyl-DHAP synthase [40] were present on the luminal side of the vesicles in a microsomal fraction, presumably containing peroxisomes, from Harderian gland.…”

Section: Discussionmentioning

confidence: 99%

“…The topographical distribution of the DHAP-AT [2,15,17,34] and the alkyl-DHAP synthase [34,40] have also been studied before. Rock et al concluded that both the DHAP-AT [15] and the alkyl-DHAP synthase [40] were present on the luminal side of the vesicles in a microsomal fraction, presumably containing peroxisomes, from Harderian gland. Bishop et al [34] studied the localization of lipid biosynthetic enzymes in rat brain.…”

Section: Discussionmentioning

confidence: 99%

Rat liver dihydroxyacetone-phosphate acyltransferase: Enzyme characteristics and localization studies

Hardeman

Bosch

1988

Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metaboli

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Peroxisomes were isolated from rat liver by pelleting a light mitochondrial (L) fraction over a 30% (w/v) Metrizamide layer. Peroxisomes were recovered as a loose pellet from the bottom of the tube and the purity of the peroxisomal fraction was calculated to be about !H%. The characteristics of dihydroxyacetone-phosphate acyltransferase (DHAP-AT) in the light mitochondrial fraction and the purified peroxisomal fraction were compared. The behaviour of the enzyme in the two fractions was very similar, except for the effect of sodium fluoride, which stimulated the activity in the L fraction 5-lo-fold and in the peroxisomal fraction only l&fold. This difference could be explained by the action of fluoride-sensitive acid phosphatases present in the L fraction that dephosphorylate palmitoyl-coenzyme A, a substrate for DHAP-AT. The localizations of DHAP-AT and alkyldihydroxyacetone-phosphate synthase in the rat liver peroxisomal membrane were studied. It is shown that in intact peroxisomes, DHAP-AT and alkyl-DHAP synthase are resistant to proteolytic inactivation by trypsin, as is fatty acid b-oxidation activity, which served as a marker for the intactness of the peroxisomal membrane. Catalase was found not to be a suitable marker to assess peroxisome intactness in view of its relative insensitivity to trypsin. In l-lauroyllysophosphatidylcholine-permeabilized peroxisomes, DHAP-AT, alkyl-DHAP synthase and B-oxidation activities were rapidly inactivated by trypsin. It is concluded that in rat liver peroxisomes, at least the active sites of the integral membrane proteins DHAP-AT and alkyl-DHAP synthase are localized exclusively at the inner surface of the peroxisomal membrane.

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Activation of alkyldihydroxyacetone phosphate synthase by detergents

Cited by 35 publications

References 36 publications

Sexual diversity of the lipid metabolism in the Harderian gland of the golden hamster

Sexual diversity of the lipid metabolism in the Harderian gland of the golden hamster

Fatty Acid Activation and Temperature Perturbation of Rat Brain Microsomal Phospholipase D

Rat liver dihydroxyacetone-phosphate acyltransferase: Enzyme characteristics and localization studies

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