Effect of sulphated glycopeptides on kinetics of 3-O-methyl glucose and 2-deoxyglucose transport by epithelial cells isolated from rabbit small intestine.

Suspensions of cells isolated from rabbit small intestine were prepared which showed a considerable rate of respiration after 4 h of their isolation. Rabbit intestinal cells accumulated 3-O-methyl-glucose by an active transport mechanism which was Na+-dependent whereas 2-deoxyglucose was transported by a saturable pathway. Analysis of the initial transport data indicated that the uptake of both sugars by cells followed Michaelis-Menten-type kinetics. These cells also showed a considerable degree of 2-deoxyglucose phosphorylation and the transport of the sugar into the cells appeared to be a rate-limiting factor for its phosphorylation. Sulphated glycopeptide had no effect on the respiration rate of these cells but it increased the transport of 3-O-methyl-glucose and 2-deoxyglucose into cells by many fold compared with untreated cells. Kinetic analysis of the data indicated that the increase in the transport was due to increased V while the Km remained unchanged. Presence of sulphated glycopeptide had no effect on the kinetics of phosphorylation of 2-deoxyglucose. These effects of sulphated glycopeptide on the transport activity of the cells have been discussed as a result of an increase in the number of sugar sites in the cell membrane due to unmasking or activation of preexisting sites owing to the interaction between the cell membrane components and highly polyanionic sulphated glycopeptides.