Table 1.

Atom pair distances (Å)

Atom pairs (P407)	X-ray	No ion, calculated	With ion, calculated
N-Na	14.27	15.61	15.44
CA–CAb	13.62	15.38	15.28
CG–CGc	12.03	13.95	14.03

^aN, Nitrogens on ring, proline.

^bC_A are the carbon atoms next to the nitrogens on the ring.

^cC_G are the carbon atoms third from the nitrogens, on the ring.