The kinetics of membrane transports involving chemical reactions

Zur Frage der Wirkung von Insulin auf die intestinale Resorption von Glucose und Fructose

“…gtiltigen Theorien durch einen aktiven Transport mit Hilfe eines Carriers dureh die Zellmembran in die verschiedenen Zellen eingeschleust [18,7,23,24,25,44,38,32,33,21,5].Auch fiir die selektive Resorption im Diinndarm wird das Vorhandensein yon Transportvorggngen gefordert [7,44]. Dadureh werden die Untersehiede in der Resorptionsgesehwindigkeit der einzelnen Monosaccharide erkl/~rt.…”

The asymmetry of the facilitated transfer system for hexoses in human red cells and the simple kinetics of a two component model

“…The simple kinetics do not necessarily exclude the insertion of intermediate stages such as proposed by Bowyer & Widdas (1958) or the enzyme model of Rosenberg & Wilbrandt (1955) but an internal transfer on the line proposed by Lieb & Stein (1970) (1972). The fact that ethylidene glucose can react, albeit differently, with the components involved in hexose transfer both on the inside and outside of the membrane but is not translocated by the system (Baker & Widdas, 1973) may also be due to intermediate reactions being involved in transfer but the present experiments give no direct evidence for these.…”

An analytical study of the kinetics of glucose movement in human erythrocytes

“…There now appears to be general agreement about the formulation of the process of sugar movement (Widdas, 1954;Rosenberg & Wilbrandt, 1955; Lefevre, 1959), and there is no departure here from this agreement though the opportunity is taken to make a few points of detail. In particular, the fact that exchange for the same or certain other sugars is more rapid than net movement, as described by Rosenberg & Wilbrandt (1957) and Lefevre & McGuiness (1960) may be used to support the argument that the sugar-occupied adsorbing sites are in a state of rapid oscillation between exposure to the inside and outside of the cell.…”