Showing papers on "Cooperative binding published in 1968"
TL;DR: A potassium transport mutant of Escherichia coli is described which is deficient in the intake of potassium, leading to four possible explanations of the mutant's phenotype.
Abstract: A potassium transport mutant of Escherichia coli is described which is deficient in the intake of potassium. The phenotype of this mutant is characterized by (i) failure to grow in K+-deficient medium, (ii) failure to accumulate K+ in K+-deficient medium, (iii) a steady-state intracellular K+ that varies sigmoidally with the medium K+ concentration, (iv) a signoidally shaped rate-concentration curve and a curved reciprocal plot for net K+ uptake kinetics, and (v) a low steady-state flux of potassium associated with a reduced influx rate constant. The data are discussed in terms of the present day models of cation transport. These models have led to four possible explanations of the mutant's phenotype: (i) a selectivity reversal such that intracellular cation binding sites bind another cation instead of K+; (ii) a structural alteration of cation binding cell proteins so that K+ is bound by “cooperative binding” (sigmoid isotherm) instead of by simple adsorption (hyperbolic isotherm); (iii) conversion of an enzyme in intermediate metabolism that rate-limits K+ uptake to an allosteric protein; (iv) conversion of the “carrier protein” for K+ to an allosteric protein.
33 citations
TL;DR: Inhibition of aminoacyl-tRNA binding by the purified initiation factors f1 and f2 could be regarded as a mechanism for ensuring that only F-met-t RNA binds initially to the entry site, thereby preventing random or non-specific binding by aminoacy ltRNA.
Abstract: Inhibition of aminoacyl-tRNA binding by the purified initiation factors f1 and f2 could be regarded as a mechanism for ensuring that only F-met-tRNA binds initially to the entry site, thereby preventing random or non-specific binding by aminoacyl-tRNA. This inhibition would be relieved by the hydrolysis of the GTP molecule normally involved in the binding of F-met-tRNA.
22 citations