RESUMO
RESUMO Glicosaminoglicanos (GAGs) são carboidratos presentes em todos os organismos que apresentam organização tissular. Glicosidases e sulfatases são as enzimas envolvidas na degradação destes compostos em vertebrados e invertebrados. O objetivo deste trabalho foi identificar a presença destas enzimas em diferentes tecidos do molusco Aplysiacervina. O molusco foi dissecado em esôfago, fígado, moela e músculo e homogeneizados separadamente. Após centrifugação os sobrenadantes (extratos brutos) foram fracionados com sulfato de amônio nas concentrações de 0-30% (F-I), 30-50% (FII) e 50-80% (FIII). Foi identificada a presença de sulfatase, β-glucuronidase, β-D-N-acetilgalactosaminidase e α-glucosaminidase nos extratos brutos de todos os tecidos investigados. A enzima α-fucosidase não foi detectada em esôfago, nos extratos brutos e F-I de moela, mas sim nas frações de fígado e músculo. A sulfatase apresentou-se mais ativa na F-III de fígado e moela com atividades específicas de 3,0 e 4,8, respectivamente. A α-glucosaminidase foi mais ativa nas frações F-III de esôfago e músculo apresentando atividades específicas de 3,9 e 2,0, respectivamente. Estes resultados indicam a existência de atividade catabólica sobre os GAGs neste invertebrado marinho.
ABSTRACT Glycosaminoglycans (GAGs) are carbohydrates present in all organisms with tissue organization. Glycosidases and sulfatases are the enzymes involved in their degradation in vertebrates and invertebrates. The objective of this work was to identify the presence of these enzymes in different tissues of the mollusc Aplysia cervina. The mollusc was dissected, separating out the esophagus, liver, gizzard and muscle, which were homogenized separately. After centrifugation the supernatants (crude extracts) were fractionated with ammonium sulfate in the concentrations of 0-30% (F-I), 30-50% (FII) and 50-80% (FIII). The presence of the sulfatase,β-glucuronidase, β-D-N-acetilgalactosaminidase and α-glucosaminidase was identified in the crude extracts of all studied tissues. α-fucosidasewasnot found in the esophagus or in the crude extracts and F-I from gizzard, but was detected in the fractions from liver and muscle. Sulfatase was more active in F-III from liver and gizzard, demonstrating specific activity of the 3.0 and 4.8, respectively. α-glucosaminidase was more active in the F-III fraction from esophagus and muscle presenting 3.9 and 2.0 specifics activities, respectively. These results indicate the existence of catabolic activity on GAGs in these marine invertebrate.
RESUMO
The distribution and structure of heparan sulfate and heparin are briefly reviewed. Heparan sulfate is a ubiquitous compound of animal cells whose structure has been maintained throughout evolution, showing an enormous variability regarding the relative amounts of its disaccharide units. Heparin, on the other hand, is present only in a few tissues and species of the animal kingdom and in the form of granules inside organelles in the cytoplasm of special cells. Thus, the distribution as well as the main structural features of the molecule, including its main disaccharide unit, have been maintained through evolution. These and other studies led to the proposal that heparan sulfate may be involved in the cell-cell recognition phenomena and control of cell growth, whereas heparin may be involved in defense mechanisms against bacteria and other foreign materials. All indications obtained thus far suggest that these molecules perform the same functions in vertebrates and invertebrates