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C Ceccarini

Publications and source records attributed to C Ceccarini.

At least 55 records · Page 3Linked to original sources
PubMed1982

Alterations of acidic and neutral glycopeptides during the post-natal growth period of the mouse.

We have examined the electrophoretic pattern of mannose-labelled glycopeptides derived from liver, pancreas, heart, brain, lung and kidney. The various organs were removed from white Swiss mice of 4-5, 20 and 40 days of age as well as from adult animals. Our data demonstrated that each organ had a characteristic ratio of acidic to neutral glycopeptides and that this ratio, in some cases, was substantially modified as the animal grew, consistent with the hypothesis that these changes might play an important role in the development and physiological function of organs.

Aging↗
PubMed1982

The purification and characterization of alpha-L-fucosidase from the hepatopancreas of Octopus vulgaris.

We have isolated and purified, by affinity chromatography with Agarose-epsilon-amino-caproyl-fucosamine, an alpha-L-fucosidase [alpha-L-fucoside fucohydrolase EC 3.2.1.51] from the hepatopancreas of Octopus vulgaris. In the purified fraction only fucosidase activity could be detected. However, two protein bands, one major (about 95 per cent) and one minor (about 5 per cent), were evident on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing also revealed two activities, pI 8.1 (major) and pI 7.3 (minor). Under denaturing conditions the molecular weight of the major band was estimated to be 52,000 while that of the minor one was 43,000. Only one major activity peak with an apparent molecular weight of 70,000--75,000 was detected by gel filtration chromatography. The enzyme has two optimal pH values, and the relative activities are temperature-dependent; one optimum is at pH 5.5 +/- 0.2 and the other at pH 3.0 +/- 0.2. We found that the enzyme has a maximum activity at about 70 degrees C, but 50 per cent of the enzyme was inactivated at 70 degrees C after 5 min. The purified enzyme, using p-nitrophenyl-L-fucoside as substrate, has a specific activity of 38.9 units/mg of protein, Km of 3.58 x 10(-4) M and Vmax of 65 mumol/min/mg of protein. alpha-L-Fucose acts as a competitive inhibitor, with a K1 of 1.2 x 10(-3) M. alpha-L-Fucosidase released radioactive fucose from cellular glycopeptides, but no detectable free fucose was released fom 5 natural substrates.

Animals↗
PubMed1981

Determination of the Structure of four glycopeptides from hen ovalbumin using 360-MHz proton magnetic resonance spectroscopy.

Four glycopeptides have been purified by Dowex and Bio-Gel P2 chromatography from Pronase digests of hen ovalbumin. The high-resolution proton magnetic resonance spectra of these glycopeptides and various products of their enzymatic digestion have been obtained at 360 MHz. By use of information derived from the spectra of a number of model compounds, an unambiguous assignment of all C1-H and Man C2-H resonances in the spectra can be made. On this basis structures are proposed for the four glycopeptides which are identical with those structures previously deduced from destructive chemical methods.

Animals↗
PubMed1981

Demonstration of heterogeneity of chick ovalbumin glycopeptides using 360-MHz proton magnetic resonance spectroscopy.

Ovalbumin glycopeptides AC-C and AC-D at various stages of purification were studied by high-field proton magnetic resonance spectroscopy (1H NMR). In a homogeneous substance, the intensity of the various resonances appears in integral amounts, while subintegral intensities usually denote mixtures of structure. We show how 1H NMR can be used to nondestructively assay the purification of major components from mixtures. In glycopeptide AC-C we have spectroscopic evidence for the four different glycopeptide species, three of which have been described [Shepherd, V., & Montgomery, R. (1978) Carbohydr. Res. 61, 147; Tai, T., Yamashita, K., Ito, S., & Kobata, A. (1977) J. Biol. Chem. 252, 6687]. However, we did detect a fourth structure not previously reported. In glycopeptide AC-D, we have spectroscopic evidence for five different compounds, only two of which have been previously reported (Tai et al., 1977; Shepherd & Montgomery, 1978).

Animals↗
PubMed1981

Synthesis and accumulation of mannose-containing glycopeptides in human fibroblast cells: possible separate pathways for neutral and acidic glycopeptides.

The normal human fibroblast, WI-38, was labelled with radioactive mannose and its incorporation, as well as the accumulation of acidic and neutral glycopeptides on the cell surface, was followed as a function of time. The transit time of newly made Pronase-released cell surface glycopeptides from their intracellular site of synthesis to the cell surface was slower in nongrowing cells than in a rapidly growing culture. When the surface glycopeptides were separated by high-voltage paper electrophoresis into neutral and acidic species, it was observed that the cell surface material was initially enriched with neutral glycopeptides. However, with time the relative proportion of acidic species increased so that by 3 h the ratio between the acidic and neutral species approached a constant value. Our data are consistent with the hypothesis that multiple pathways for asparagine-linked glycoprotein biosynthesis are possible.

Acids↗
PubMed1979

Fractionation of mannose-labeled neutral glycopeptides by QAE-Sephadex chromatography.

Mannose-labeled cellular glycopeptides derived from human diploid fibroblasts (KL-2) were separated into two classes by QAE-Sephadex chromatography. High-voltage paper electrophoresis and Sephadex G-50 chromatography were used to characterize the glycopeptides further. At least five distinct neutral fractions were isolated with molecular weights ranging from 1050 to 2000 daltons. A linear gradient of ammonium acetate eluted a heterogeneous population of acidic glycopeptides. The use of QAE-Sephadex enables a single-step fractionation of both neutral and acidic glycopeptides on one column. The technique appears to be sensitive enough to distinguish growth-dependent alterations between growing and non-growing cells.

Chemical Phenomena↗
PubMed1977

Studies on mannose-containing glycopeptides from a normal and an SV40 transformed human cell.

The oligosaccharide moiety of cell-surface mannose-labelled glycopeptides from a normal (WI38) and an SV40 transformed cell (W118Va) have been investigated using specific glycosidases. Partially purified mannose-containing glycopeptides were separated into acidic and neutral species by high voltage paper electrophoresis. Endo-beta-N-acetylgucosaminidase D, in the presence of three exoglycosidases, released from the acidic glycopeptides of non-growing cells a product completely absent in growing cells. However, the acidic species from growing WI18 Va and WI38 were found to be similar in the products released by enzyme digestion. The neutral species from growing normal cells contained a proportion of the glycopeptides resistant to endoglycosidase D while those from the non-growing cells were almost free of these resistant species. The SV40 transformed cells were further enriched, when compared to normal cells (WI38), in these neutral resistant species. We suggest that the oligomannosyl core of the majority of the susceptible species contains three mannose residues while that of the resistant species contains between six and eight.

Acetylglucosaminidase↗
PubMed1976

Characterization of mannose-labeled glycopeptides from human diploid cells and their growth-dependent alterations.

Mannose-labeled glycopeptides were prepared from human diploid fibroblasts harvested by brief pronase digestion. Combined use of endo-beta-N-acetylglucosaminidase H and D converted most of the mannose-label into arrays of oligosaccharides. They were separated by paper chromatography and were characterized by Sephadex G-25 column chromatography, by affinity column chromatography on concanavalin A-Sepharose, and by successive digestion with alpha-mannosidase and beta-mannosidase. The results indicated that mannose residues existed as clusters of various sizes, which we refer to as "oligomannosyl cores". The large oligomannosyl cores (approximately 7 to 8 mannosyl residues) were predominant in the glycopeptides from growing cells and were preferentially associated with neutral glycopeptides, similar to Unit A glycopeptides of thyroglobulin (mannose-N-acetylglucosamine unit). In glycopeptides from nongrowing cells, the ratio of the large oligomannosyl cores decreased, accompanying the increase of a small oligommanosyl core consisting of 3 mannosyl residues. The small core was preferentially associated with acidic glycopeptides.

Acetylglucosaminidase↗
PubMed1976

Some paradoxical effects of inhibitors of protein synthesis on protein turnover in cultured human cells.

Low concentrations of cycloheximide, sufficient to block net protein synthesis in growing normal and cancer cells, had no effect on protein turnover, i.e. either the incorporation of labeled amino acids from media lacking other amino acids essential for growth, or the loss to the medium of amino acids from prelabeled cells. At the concentrations that blocked growth, the rate of amino acid incorporation from complete medium was reduced to the "turnover level" i.e. the rate of incorporation seen in amino acid-deficient media. Protein turnover was inhibited only at higher concentrations of the inhibitor. Qualitatively similar results have been obtained with puromycin, anisomycin, emetin and tylocerebrine.

Anisomycin↗
PubMed1975

Appearance of smaller mannosyl-glycopeptides on the surface of a human cell transformed by simian virus 40.

When fucosyl surface glycopeptides from growing normal human cells (WI 38) were compared with those derived from nongrowing cells the former were enriched in high-molecular-weight species. However, a line of human cells (WI 18Va) transformed by simian virus 40 appeared to have fucosyl-glycopeptides similar in size distribution to those from rapidly growing non-transformed cells (WI 38). I propose that the enrichment in high molecular weight species in these cells might be growth- rather than transformation-dependent. Using radioactive mannose to label surface glycopeptides, I observed that those derived from transformed cells (WI 18Va) were smaller than those from rapidly growing normal cells. Thus differences in size distribution may not be adequate criteria to evaluate the growth-dependent alterations in cell surface glycopeptides.

Cell Line↗
PubMed1975

Growth-dependent alterations in oligomannosyl cores of glycopeptides.

Mannose-labeled glycopeptides from the surface of growing and nongrowing human diploid cells (KL-2) were separated into neutral glycopeptides and acidic glycopeptides by paper electrophoresis. Growth-dependent alterations occurred in oligomannosyl cores in the neutral glycopeptides; namely, the neutral glycopeptides from the surface of growing cells were more resistant to endo-beta-N-acetylglucosaminidase D but were more susceptible to alpha-mannosidase (EC 3.2.1.24; alpha-D-mannose mannohydrolase) than those derived from the surface of nongrowing cells. Another growth-dependent change was found when the endoglycosidase-resistant material from acidic glycopeptides was compared by paper electrophoresis at pH 1.9. The material from the surface of nongrowing cells contained a component that was absent or greatly reduced in growing cells.

Acetylglucosaminidase↗
PubMed1971

pH as a determinant of cellular growth and contact inhibition.

1) Both the growth rate and the maximum population density of several normal, virus-transformed, and cancer cells were markedly pH-dependent; the optimum varied from pH 6.9 to 7.8. At the optimum pH, some diploid human cells attained population densities comparable to those of cancer or virus-transformed cells. Contact inhibition of growth is facilitated by repeated fluctuations of pH in nonphysiological ranges, and may not be an intrinsic and necessary attribute of diploid cells in culture. 2) At pH 8.3, at which there was little or no cellular multiplication, the protein content per cell increased 2- to 5-fold over a period of 10-16 days, and was slowly reversed to normal concentrations on restoration of pH to the optimal range. 3) Uridine uptake by contact-inhibited human cell cultures was stimulated by refeeding with salt solution, and to the same extent as by complete (serum-supplemented) growth medium; that immediate increase did not involve the reinitiation of cellular growth and multiplication. Contact inhibition was, however, reversed in 2-4 days by an appropriate increase in the serum concentration of the medium.

Adenoviridae↗