Effect of calcium on sulfate uptake by barley roots [calcium, Hordeum, uptake site, transition site]
1980
Skjelbreid, E. | Nissen, P. (Bergen Univ. (Norway). Dept. of Microbiology and Plant Physiology)
Sulfate uptake by excised roots of barley (Hordeum vulgare L.) was maximal in the presence of about 3 x 10('-3)M CaCl(,2). Kinetic studies contraindicate a stoichiometric binding of calcium to the carrier for sulfate, in contrast to findings of Cuppoletti and Segel (Biochemistry 14: 4712-4718, 1975) for the filamentous fungus Penicillium notatum. In barley, calcium affects the K(, m) but not the V(, max) for sulfate uptake, presumably by altering the conformation and, thereby, the affinity of the carrier. Calcium also affects the transition site for sulfate uptake.
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