The biosynthesis of gangliosides. Labelling of rat brain gangliosides <i>in vivo</i>

Maccioni, Hugo J. F.; Arce, Augusto; Caputto, Ranwel

doi:10.1042/bj1251131

Cited by 60 publications

(23 citation statements)

References 15 publications

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“…The specific activities of the sialidase stable sialic acid were lower, in all cases, than those of the labile sialic acid. These results confirm those obtained previously by us [3] but they are in contradiction to those of Suzuki and Korey [1] and Maccioni et al [2]. The reliability of our results has, however, been increased by the fact that the standard deviation of the specific activity determinations was only 7%.…”

Section: Discussionsupporting

confidence: 67%

“…The problem of a possible precursor-product relationship between the major brain gangliosides has earlier been studied in vivo by Suzuki and Korey [1 ], Maccioni and colleagues [2] and ourselves [3]. Labelled acetate and glucosamine were injected intracerebrally and the specific activities of sialidase labile and stable sialic acid of the individual gangliosides were determined at different intervals after precursor injection.…”

Section: Introductionmentioning

confidence: 99%

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Further in vivo studies on the biosynthetic relationship between the major brain gangliosides in rat

1974

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Section: Discussionsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Further in vivo studies on the biosynthetic relationship between the major brain gangliosides in rat

1974

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“…In fact, these two enzymes, from a strictly metabolic point of view, may be responsible for a "sialylation-desialylation cycle" implicating the sialylglycoconjugates occurring in the same membranes. In the case of gangliosides several authors (Maccioni et al, 1971;Holm and Sven-nerholm, 1972;Ledeen et al, 1976) looked in vivo for evidence of partial turnover of gangliosides, but the results indicated that the individual gangliosides appear to be metabolized as a unit. These investigations, extending the classical one on the biosynthesis of gangliosides (Suzuki, 1964), followed, after a single pulse of injected radioactive precursor, the course of radioactivity incorporation into the individual saccharide residues of the gangliosides in their final site, the neuronal plasma membranes.…”

Section: Discussionmentioning

confidence: 99%

Occurrence of Sialyltransferase Activity in the Synaptosomal Membranes Prepared from Calf Brain Cortex

Preti

Fiorilli

Lombardo

et al. 1980

Journal of Neurochemistry

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The possible occurrence of sialyltransferase activity in the plasma membranes surrounding nerve endings (synaptosomal membranes) was studied, using calf brain cortex. The synaptosomal membranes were prepared by an improved procedure which provided: (a) a „nerve ending fraction” consisting of at least 85% well‐preserved nerve endings and containing only small quantities of membranes of intracellular origin; (b) a „synaptosomal membrane fraction” carrying high amounts of authentic plasma membrane markers (Na+‐K+ ATPase, 5′‐nucleotidase, sialidase, gangliosides) with values of specific activity four to fivefold higher than those in the „nerve ending fraction” and very small amounts of cerebroside sulphotransferase, marker of the Golgi apparatus, and of other markers of intracellular membranes (rotenone‐insensitive NADH and NADPH: cytochrome c reductases), the specific activities of which were, respectively, 0.5‐ and 0.7‐fold that in the „nerve ending fraction”. Thus the preparation of synaptosomal membranes used had the characteristics of plasma membranes and carried a negligible contamination of membranes of intracellular origin. The distribution of sialyltransferase activity in the main brain subcellular fractions (microsomes; P2 fraction; nerve ending fraction; mitochondria) resembled most closely that of thiamine pyrophosphatase, the enzyme known to be linked to the Golgi apparatus and the plasma membranes and of acetylcholine esterase, the enzyme known to be linked to either intracellular or plasma membranes. The enrichment of sialyltransferase activity in the „synaptosomal membrane fraction”, referred to the „nerve ending fraction”, was practically the same as that exhibited by authentic plasma membrane markers. All this is consistent with the hypothesis that in calf brain cortex sialyltransferase has two different subcellular locations: one at the level of intracellular structures, most likely the Golgi apparatus (as described by other authors), the other in the synaptosomal plasma membranes. The basic properties (pH optimum, V/S, V/t and V/protein relationships) and detergent requirements of the synaptosomal membrane‐bound sialyltransferase were established. The highest enzyme activities were recorded on exogenous acceptors, lactosylceramide and ds‐fetuin. The Km values for CMP‐NeuNAc were different using lactosylceramide and ds‐fetuin as acceptor substrates (0.57 and 0.135 mm, respectively); the thermal stability of the enzyme acting on glycolipid acceptor was higher than that on the glycoprotein acceptor; the effect of detergents was different when using glycoprotein from glycolipid acceptors; no competition was observed between lactosylceramide and ds‐fetuin. Thus the synaptosomal membranes carry at least two different sialyltransferase activities: one acting on lactosylceramide (and glycolipid acceptors), the other working on ds‐fetuin (and glycoprotein acceptors). Ganglioside GM3 was recognized as the product of synaptosomal membrane‐bound sialyltransferase activity working on lactosylceramide ...

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“…The first method gives reliable results only when the in-corporation of radioactivity is negligible, with regard to the loss of radioactivity-in other words, when the specific radioactivity of the nucleotidesugar is negligible with regard to the specific radioactivity of the bound sugar; but for the second method, the specific radioactivity of the nucleotide-sugar has to be measured with a high accuracy to allow calculation of the turnover rate of the glycoconjugate. Several investigators have studied the labelling and turnover of glycoconjugates in brain by the first method, after injection of labelled glucosamine (Burton et a]., 1963; Suzuki, 1967; Barondes, 1968; Barondes and Dutton, 1969; Dutton and Barondes, 1970; Zatz and Barondes, 1970; Maccioni et al, 1971; Holian et al, 1971; Holm and Svennerholm, 1972; ; Van Nieuw Amerongen et al, 1974), fucose (Dutton and Barondes, 1970; Zatz and Barondes, 1970;Quarles and Brady, 1971; Margolis and Margolis, 1972; Margolis and Gomez, 1973) or N-acetylmannosamine (Quarles and Brady, 1971; Holm et al, 1974;Landa et al, 1977).…”

mentioning

confidence: 99%

Turnover of Free Sialic Acid, CMP‐Sialic Acid, and Bound Sialic Acid In Rat Brain

Ferwerda

Blok

Heijlman

1981

Journal of Neurochemistry

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Adult male rats were injected intraventricularly with N-[3H]acetylmannosamine. After different time intervals the rats were killed and free sialic acid, CMP-sialic acid, lipid- and protein-bound sialic acid were isolated from brain and the specific radioactivities determined. Maximal specific radioactivity was reached after approximately 4 h for CMP-sialic acid, after 10-12 h for free sialic acid and after approximately 42 h for lipid- and protein-bound sialic acid. After some days the specific radioactivities of all four pools were the same and decreased equally, with a calculated turnover rate of approximately 3.5 weeks. The conclusion was that this phenomenon was the result of reutilisation of sialic acid and/or precursors. Therefore, the calculated turnover is not the turnover of bound sialic acid, but merely the rate of leakage of sialic acid and/or precursors out of the brain, so that no real turnover can be measured by this method. The first few hours after injection the specific radioactivity of CMP-sialic acid rose above that of free sialic acid. It is supposed that a compartmentalization exists of free sialic acid. The newly synthesised sialic acid molecules are not secreted into the cytoplasmic pool but are preferentially used for the synthesis of CMP-sialic acid. The results and conclusions are discussed in view of the general problems concerning turnover measurements of glycoconjugates.

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The biosynthesis of gangliosides. Labelling of rat brain gangliosides in vivo

Cited by 60 publications

References 15 publications

Further in vivo studies on the biosynthetic relationship between the major brain gangliosides in rat

Further in vivo studies on the biosynthetic relationship between the major brain gangliosides in rat

Occurrence of Sialyltransferase Activity in the Synaptosomal Membranes Prepared from Calf Brain Cortex

Turnover of Free Sialic Acid, CMP‐Sialic Acid, and Bound Sialic Acid In Rat Brain

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