Sialyltransferase activity in regenerating rat liver

Serafini‐Cessi, Franca

doi:10.1042/bj1660381

Cited by 44 publications

(13 citation statements)

References 28 publications

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“…cholate resulted only in a moderate activation of the enzyme (maximum increase of 60 "/, at 0.08 'x deoxycholate; Table 2). This is in contrast to the marked stimulation of activity observed for rat liver sialyltransferase with Triton X-100 [21] or sodium deoxycholate [22]. The equine system showed good activity for both sialic acids in the range of pH 6 to 7.5 as shown in Fig.…”

Section: Properties Of the Siulyltrunsferase Systemcontrasting

confidence: 56%

Metabolism of 4‐O‐Methyl‐N‐acetylneuraminic Acid a Synthetic Sialic Acid

Beau

Schauer

1980

European Journal of Biochemistry

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1. 4-0-Methyl-N-acetylneuraminic acid shows a strong positive periodate-thiobarbiturate reaction. The mechanism of dye formation in this test for sialic acids is discussed in view of the studies already published.2. An efficient preparation of a tritium-labelled 4-0-methyl-N-acetylneuraminic acid, with high specific radioactivity, by an oxymercuration-demercuration procedure is presented.3. Sialyltransferase activities in microsomal fractions of equine liver using desialylated fetuin are studied. The enzyme activity, assayed in a radioactive procedure, shows an apparent K , value for CMP-N-acetylneuraminic acid of 0.7 mM, whereas this value is 3.4 mM for CMP-4-0-methyl-N-acetylneuraminic acid. Differences are also observed in the maximal velocity for the two substrates.4. The equine liver system can be used to prepare substantial amounts of fetuin containing radioactive N-acetylneuraminic acid or 4-0-methyl-N-acetylneuraminic acid. The isolated reaction products show similar sialic acid release by treatments with acid or fowl-plague virus neuraminidase. In contrast, 4-0-methyl-N-acetylneuraminic acid-fetuin displays a marked resistance to desialylation by Vibrio cholerae neuraminidase.5. Free 4-0-methyl-N-acetylneuraminic acid is completely resistant to the action of acylneuraminate pyruvate-lyase. It does not inhibit the enzymic cleavage reaction of N-acetylneuraminic acid.6. The influence of a substitution at C-4 of neuraminic acid on the enzymatic reaction mechanisms is discussed.The acylneuraminic acids (sialic acids), widely distributed in animal tissues, are important components of oligosaccharides, glycolipids and glycoproteins. The occurrence and nature of various Nacylated and O-acylated neuraminic acids is now well documented [l -31, and the pattern distribution is characteristic for the animal species. Sialic acids are implicated in many cellular processes [4], and the high number of the 0-acylated derivatives points to the importance of understanding the biological role of these substances. In a preliminary approach, a precise evaluation of the behaviour of the main enzymes involved in the metabolism of sialic acids is

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Section: Properties Of the Siulyltrunsferase Systemcontrasting

confidence: 56%

Metabolism of 4‐O‐Methyl‐N‐acetylneuraminic Acid a Synthetic Sialic Acid

Beau

Schauer

1980

European Journal of Biochemistry

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“…? SD2 * SD adding 1 ml of FTA and the acid-insoluble radioactivity was determined (Serafini-Cessi, 1977). The theoretical concentration of the acceptor sites in AST was calculated assuming 77,000 as the molecular weight of transferrin with 4 acceptor sites in each molecule, owing to the presence of 2 diantennary N-linked chains (Spik et al, 1975).…”

Section: Carcinoma (11)mentioning

confidence: 99%

Increased CMP‐NeuAc:Galβ1,4GlcNAc‐R α2,6 sialyltransferase activity in human colorectal cancer tissues

Olio

Malagolini

Stefano

et al. 1989

Intl Journal of Cancer

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141

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The sialyltransferase activities of 10 human colorectal specimens were compared with those of the corresponding adjacent normal mucosa. Using asialofetuin as an acceptor we found, in tumor tissues of 9 out of 10 patients, an increased sialyltransferase activity towards the N-linked chains as determined upon peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase (PNGase) treatment. On the contrary, the activity towards the O-linked chains was not significantly changed. When the specificity of the sialyltransferase acting on N-linked chains was investigated by using N-acetyl-lactosamine (Gal beta 1,4GlcNAc) as an acceptor, we found that the alpha 2,6 sialyltransferase activity expressed by both normal and tumor colorectal tissues was far higher than the alpha 2,3-activity and that alpha 2,6 was the only sialyltransferase activity increased in tumor tissues. Kinetic analysis revealed that normal and tumor alpha 2,6 sialyltransferases have the same apparent Km for the acceptor substrate (469 and 465 microns), but normal enzyme has a higher Km for CMP-NeuAc (303 microns) than the tumor enzyme (50 microns). The higher affinity of tumor enzyme for the nucleotide-sugar might partially explain its increased activity in tumor tissues. In addition, tumor tissues contain a lower amount of sialic acid despite the increase in alpha 2,6 sialyltransferase activity.

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“…Dysfibrinogenaemia is not dependent on the fibrinogen concentration, which may vary from reduced to increased [8], but appears to be the result of re-expression of Thrombosis Research 135 (2015) [1124][1125][1126][1127][1128][1129][1130] fetal genes coding for fetal fibrinogen production in liver cell regeneration [9]. The content of sialic acid is increased in aberrant fibrinogen molecules from patients with liver disease, as in newborn infants, and raised serum and liver sialyltransferase activity has been described in association with hepatocellular regeneration [10,11]. These fibrinogen molecules are characterized by prolonged clotting time, normal release of fibrinopeptide A, and delayed polymerization of fibrin monomers.…”

Section: Introductionmentioning

confidence: 99%