Table 2.

Cavity volumes and xenon binding affinities for the inactive and active conformers of CheY

	Ka(Xe)a/M−1		Cavity volumeb/Å 3
	H1-β3 cavity	β4-H4 cavity	H1-β3 cavity	β4-H4 cavity
Inactive	27 ± 8	35 ± 8	74c	92c
Active	27 ± 8	22 ± 8	58d	116e

^a Xenon binding affinities were determined as described in the Materials and Methods section.

^b Cavity volumes were calculated from:

^cSimonovic and Volz 2001,

^d this work,

^e this work with Tyr¹⁰⁶ rotated to the out position.