Figure 3.

A stereo view of superposition of K⁺ loops from six independent molecules of metal-free (FosA, light gray) and metal-bound (PA1129, dark gray) enzymes. The K⁺ loops in the metal-free enzyme adopt a variety of conformations in the six monomers of the asymmetric unit. The side chain of glutamate 98 is included in the loops that represent the extremes of the spectrum of conformations.