4-O-beta-D-galactopyranosyl-D-xylose: a new synthesis and application to the evaluation of intestinal lactase.
4-O-beta-D-Galactopyranosyl-D-xylose (2) was prepared from benzyl 2,3-O-isopropylidene-beta-D-xylopyranoside by glycosylation with 2,3,4,6-tetra-O-benzoyl-alpha-D-galactopyranosyl bromide and subsequent deprotection. Compound 2 was hydrolyzed in vitro by intestinal lactase; the Vmax was 25% of that with lactose and the Km was 370mM (cf. 27mM for lactose). Oral administration of 2 suckling rats led to urinary excretion of D-xylose which could be estimated colorimetrically.
Rivera-Sagredo
A
A
Grupo de Carbohidratos, Instituto de Química Orgánica, C.S.I.C., Madrid, Spain.
Fernández-Mayoralas
A
A
Jiménez-Barbero
J
J
Martín-Lomas
M
M
Villanueva
D
D
Aragón
J J
JJ
D000284:Administration, Oral; D000375:Aging; D000818:Animals; D000833:Animals, Suckling; D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000138:chemical synthesis / Q000378:metabolism*; D007422:Intestines / Q000201:enzymology*; D043322:Lactase; D007785:Lactose / Q000378:metabolism; D008969:Molecular Sequence Data; D012756:Sheep; D014994:Xylose / Q000652:urine; D001616:beta-Galactosidase / Q000378:metabolism*
D004187:Disaccharides; C073827:4-O-galactopyranosylxylose; D014994:Xylose; D043322:Lactase; D001616:beta-Galactosidase; D007785:Lactose