. Electrolytes in biological systems, incorporating papers presented at a symposium at the Marine Biological Laboratory in Woods Hole, Massachusetts, on September 8, 1954. Electrophysiology; Electrolytes; Electrolytes; Electrophysiology; Physiology, Comparative. 70 ELECTROLYTES IN BIOLOGICAL SYSTEMS U02++-binding sites of the cell were chemically related to the polyphosphates. In addition to the polyphosphates, a second species of UO^"*"^ binding site was also present on the cell surface of yeast, which possessed a considerably lower affinity for the cation. A number of other bivalen
. Electrolytes in biological systems, incorporating papers presented at a symposium at the Marine Biological Laboratory in Woods Hole, Massachusetts, on September 8, 1954. Electrophysiology; Electrolytes; Electrolytes; Electrophysiology; Physiology, Comparative. 70 ELECTROLYTES IN BIOLOGICAL SYSTEMS U02++-binding sites of the cell were chemically related to the polyphosphates. In addition to the polyphosphates, a second species of UO^"*"^ binding site was also present on the cell surface of yeast, which possessed a considerably lower affinity for the cation. A number of other bivalent cations were found to compete with U02"'"'" for the cell-surface sites (58). However, relatively high concentrations of the competing cations were required to displace the UO-"'^. The binding of other cations was studied in more detail using isotope technique with Ca** and es- 80 - 60 40 20- TIME IN MINUTES 0 20 40 60 80 100 120 140 160 Fig. 2. The time-course of uptake of Ca"*^ by yeast cells. 180. 60 uj Fjg. 3. The uptake of Mn^'* by K yeast cells as a function of Mn++ 40 = concentration. 2 4 6 8 10 12 14 EQUILIBRIUM CONCENTRATION OF Mn** IN M/L x 10^ pecially with Mn^"* (54). As with 1702+^, the binding of Ca++ and Mn++ was reversible and reached equilibrium rapidly. Within 2 minutes, the earliest observation, the reaction was essentially complete (fig. 2). Mn++ is not bound by the cell in such a stable configuration as UOo"*^. For this reason, the curve representing Mn++ uptake as a function of Mn++ concentration does not rise so sharply to an asymptote (fig. 3). As with 1102"^"'', the binding of Mn++ can be expressed by a simple relationship: ^ _ (M)(Y) 0). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Shanes, Abraham M. (Abraham Morris), 1917-; Society o
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