“…For instance, many workers reported biphasic double-reciprocal or Hofstee-Eadie plots, and suggested that these indicated two K,,, values for separate reactive sites, or were due to complex interactions involving magnesium ions [3,7,8]. However, there is no doubt that the enzyme is monomeric at low concentrations [9], and crystallographic studies suggest that both the yeast and the horse-muscle enzyme possess only one tight binding site for adenine nucleotides [lo, 111. Curved or biphasic plots could be made more linear by alterations of magnesium ion concentrations, or changing the buffers [3], but this did not explain the anomalies.…”