Uptake of Benzyladenine by Tuber Slices of Jerusalem Artichoke (Helianthus tuberosus L.) over a Wide Concentration Range.

Uptake of the cytokinin benzyladenine by tuber slices of Jerusalem artichoke (Helianthus tuberosus L.) increased with the concentration of benzyladenine in the medium in the range 10(-8) to 10(-4) molar. The kinetics of uptake could be precisely represented by four phases of a single, multiphasic isotherm. K(m) and V(max) increased in a regular manner upon transition to higher phases. The fit to multiphasic kinetics was significantly better than the fit to cooperative kinetics or to the sum of four independent Michaells-Menten terms.