RESUMO
Activity of a hitherto unknown (1----3)-alpha-L-fucosyltransferase that acts on IV3-alpha-NeuAc-nLcOseCer as acceptor substrate was demonstrated in human amniotic fluid. The 14C-labelled product IV3-alpha-NeuAc-III3-alpha-Fuc-nLcOseCer was detected autoradiographically after t.l.c. and identified after desialylation by immunostaining with monoclonal antibody Leu Ml. The enzyme is assumed also to catalyze the last step in the biosynthesis of sialyl-X antigen carried by mucins in human amniotic fluid.
Assuntos
Líquido Amniótico/enzimologia , Fucosiltransferases/metabolismo , Glicolipídeos/biossíntese , Hexosiltransferases/metabolismo , Configuração de Carboidratos , Cromatografia em Camada Fina , Humanos , Antígenos CD15 , Fatores de TempoRESUMO
A soluble alpha(1-3)-L-fucosyltransferase, which accepts carbohydrates of the general structure NeuAc alpha(2-3)Gal beta(1-4)GlcNAc beta-R as substrates and which is involved in the biosynthesis of the tumor-associated sialyl-LeX determinant, was purified about 125-fold from human amniotic fluid by a one-step affinity chromatography on fetuin-agarose. Upon SDS gel electrophoresis, the purified enzyme revealed a protein band with a relative molecular mass (Mr) of about 62,000. The enzyme acted equally well on sialoglycoproteins and their desialylated derivatives.
Assuntos
Líquido Amniótico/enzimologia , Fucosiltransferases/isolamento & purificação , Hexosiltransferases/isolamento & purificação , Cromatografia de Afinidade , Cromatografia por Troca Iônica , Eletroforese em Gel de Poliacrilamida , Feminino , Humanos , Testes de Precipitina , Sefarose , alfa-FetoproteínasRESUMO
Biosynthesis of the sialyl-Lex determinant (NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)-GlcNAc beta 1-3-R) in human amniotic fluid has been shown to proceed via the same sequence of glycosylation steps established previously for lung carcinoma PC 9 cells (Holmes, E. H., Ostrander, G.K. & Hakomori, S. (1986) J. Biol. Chem. 261, 3737-3743): sialylation of type-2-chain-precursor substrates (paragloboside) by an amniotic alpha 2-3-sialyltransferase precedes fucosylation of sialylated intermediates (sialosyl paragloboside) by an organ-characteristic alpha 1-3-L-fucosyltransferase.
Assuntos
Líquido Amniótico/enzimologia , Glicolipídeos/biossíntese , Sialiltransferases/metabolismo , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Concentração de Íons de Hidrogênio , Cinética , Antígenos CD15 , GravidezRESUMO
Phytochemical analysis of leaves from ENCELIOPSIS NUDICAULIS, E. NUDICAULIS var. CORRUGATA, and GERAEA CANESCENS afforded numerous methylated flavonoids present as resin constituents as well as benzofurans and related compounds extracted from roots. Five new dihydroflavonols present on the leaf surfaces were identified based on their spectral data and on those of the corresponding flavonols obtained by oxidation with NaHSO (3).