RESUMO
The reaction sequence for the biosynthesis of gangliosides by mouse neuroblastoma cells has been investigated by studying the pattern of incorporation of labeled precursors into sialoglycosphingolipids. Cultured NB41A cells incorporated N-[3H]acetylmannosamine into the sialic acid moiety of GM3 in less than 10 min. Labeled GM2 was not detected in cells incubated for less than 30 min, while measurable radioactivity did not appear in GM1 until after 60 to 90 min. Analogous experiments were carried out using [14C]galactose. No significant amount of labeled hexose was incorporated into asialo-GM2 during 60 min of culture. These studies are in accord with results of previous studies on glycosyltransferases of NB41A cells (Kemp, S. F., and Stoolmiller, A. C. (1976), J. Neurochem. 26, 723-732), and further support the concept that the pathway of synthesis of gangliosides proceeds via GM3 leads to GM2 leads to GM1.
Assuntos
Glicoesfingolipídeos/biossíntese , Neuroblastoma/metabolismo , Animais , Linhagem Celular , Meios de Cultura , Gangliosídeo G(M1)/biossíntese , Gangliosídeo G(M2)/biossíntese , Gangliosídeo G(M3)/biossíntese , Galactose/metabolismo , Glucose/metabolismo , Glicoesfingolipídeos/metabolismo , Hexosaminas/metabolismo , Cinética , Camundongos , Ácidos Siálicos/metabolismoAssuntos
Fucosil Galactose alfa-N-Acetilgalactosaminiltransferase/metabolismo , Gangliosídeo G(M2)/biossíntese , Gangliosídeos/biossíntese , Glicoesfingolipídeos/biossíntese , Hexosiltransferases/metabolismo , Neuroblastoma/metabolismo , Sialiltransferases/metabolismo , Transferases/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , Fenômenos Químicos , Química , Cinética , Magnésio/metabolismo , Manganês/metabolismo , CamundongosAssuntos
Sulfatos de Condroitina/biossíntese , Condroitina/análogos & derivados , Condrossarcoma/metabolismo , Glicosaminoglicanos/biossíntese , Proteoglicanas/biossíntese , Animais , Osso e Ossos/embriologia , Osso e Ossos/enzimologia , Cartilagem/enzimologia , Cátions Bivalentes , Galinhas , Galactosiltransferases/metabolismo , Glucuronosiltransferase/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Neoplasias Experimentais/metabolismo , Pentosiltransferases/metabolismo , Ratos , Uridina Difosfato XiloseAssuntos
Cetoses , Açúcares Ácidos , Aldeídos , Arabinose , Cromatografia por Troca Iônica , Cromatografia em Papel , Glicolatos , Cetoses/biossíntese , Cetoses/síntese química , Métodos , Oxaloacetatos , Pseudomonas/metabolismo , Estereoisomerismo , Açúcares Ácidos/biossíntese , Açúcares Ácidos/síntese químicaAssuntos
Hidroliases/análise , Aldeído Oxirredutases/análise , Sulfato de Amônio , Arabinose/análogos & derivados , Fosfatos de Cálcio , Cromatografia , Cromatografia DEAE-Celulose , Cromatografia em Gel , Cristalização , Precipitação Fracionada , Hidroliases/antagonistas & inibidores , Hidroliases/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Métodos , Peso Molecular , Pseudomonas/enzimologia , Sonicação , Espectrofotometria , Estreptomicina , Açúcares ÁcidosAssuntos
Glicosaminoglicanos , Erros Inatos do Metabolismo dos Carboidratos/metabolismo , Células Cultivadas , Condroitina/metabolismo , Córnea/metabolismo , Opacidade da Córnea/metabolismo , Dermatan Sulfato/metabolismo , Fibroblastos/metabolismo , Galactose/metabolismo , Glucosamina/metabolismo , Glicosaminoglicanos/metabolismo , Heparina/análise , Heparina/metabolismo , Heparina/uso terapêutico , Humanos , Ácido Hialurônico/metabolismo , Hialuronoglucosaminidase/metabolismo , Deficiência Intelectual/metabolismo , Masculino , Mucopolissacaridoses/metabolismo , Mucopolissacaridose IV/metabolismo , Proteoglicanas/metabolismo , Retinose Pigmentar/metabolismo , Pele/metabolismo , Coloração e Rotulagem , Sulfatases/metabolismo , Testículo/enzimologiaAssuntos
Astrocitoma/enzimologia , Cerebrosídeos/farmacologia , Glucosidases/antagonistas & inibidores , Neuroblastoma/enzimologia , Animais , Astrocitoma/metabolismo , Astrocitoma/patologia , Radioisótopos de Carbono , Células Cultivadas , Cerebrosídeos/metabolismo , Modelos Animais de Doenças , Galactosidases/antagonistas & inibidores , Gangliosídeos/metabolismo , Doença de Gaucher/enzimologia , Glucuronidase/antagonistas & inibidores , Glicosídeo Hidrolases/antagonistas & inibidores , Hexosaminidases/antagonistas & inibidores , Humanos , Concentração de Íons de Hidrogênio , Lactente , Lisossomos/enzimologia , Camundongos , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Ratos , Radioisótopos de EnxofreRESUMO
Extracts of cultured normal human skin fibroblasts released radioactivity from a (14)C-labeled heptasaccharide prepared by addition of [(14)C]N-acetylgalactosamine to the nonreducing terminus of a hexasaccharide derived from chondroitin 4-sulfate whereas fibroblast extracts from patients with Tay-Sachs and Sandhoff-Jatzkewitz diseases did not. The results suggest that N-acetyl-beta-hexosaminidase A is responsible for degradation of the oligosaccharide substrate.
Assuntos
Glicosaminoglicanos/metabolismo , Hexosaminidases/metabolismo , Erros Inatos do Metabolismo dos Carboidratos/enzimologia , Isótopos de Carbono , Células Cultivadas , Cumarínicos/biossíntese , Fibroblastos , Galactosamina/biossíntese , Humanos , Deficiência Intelectual/enzimologia , Lipidoses/enzimologia , Mucopolissacaridoses/enzimologia , Mucopolissacaridoses/genética , Oligossacarídeos/metabolismo , Retinose Pigmentar/enzimologiaRESUMO
Chick-limb mesodermal cells have been maintained in tissue culture under conditions that permit development of muscle and cartilage. 3-Acetylpyridine, a nicotinamide-antagonized muscle teratogen, potentiates chondrogenic expression in cell cultures, as evidenced by histological and biochemical criteria, including the production of chondromucoprotein. Xylosyltransferase and N-acetylgalactosaminyltransferase are two enzymes required for chondromucoprotein synthesis; the specific activities of these enzymes were measured in differentiating mesodermal cells cultured for various periods of time in the presence and absence of 3-acetylpyridine and in intact limb tissue. The ratios of specific enzyme activities were nearly the same in both cultured cells and limb tissue, although the levels of both transferases increased severalfold during chondrogenic expression by mesodermal cells in culture. 3-Acetylpyridine causes the specific activities of xylosyl- and N-acetylgalactosaminyltransferases to increase 10- and 2-fold, respectively, above those of untreated cultures. Compared to the ratio of transferase activities in limb tissue and differentiating cell cultures, 3-acetylpyridine appears to increase the activity of xylosyltransferase, the initiator of chondroitin sulfate chain synthesis, more than does N-acetylgalactosaminyltransferase; this finding implies that the synthesis of these two enzymes may be separately regulated.