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Kinetic Characteristics Of Chloroplast Glucose Transport, Jerome Servaites, Donald Geiger

Donald R. Geiger

Influx of labelled D‐glucose into isolated spinach (Spinacia oleracea L. cv. Melody hybrid) chloroplasts was initially rapid followed by a period ofslower influx. The stroma glucose concentration attained equilibrium rapidly with low external glucose concentrations and the two were linearly proportional. The period of slower influx resulted from conversion of glucose to acidic products that remained trapped in thechloroplast. As the external glucose concentration increased, the stroma glucose concentration increased less and less, attaining a maximal concentration of 72 mol m–3. The maintenance of an equilibrium stroma glucose concentration lower than that in the external medium is evidence that plastid …