. 2014 Aug 13;10(9):3871–3884. doi: 10.1021/ct5005214

Table 3. Key HMBPP Bond Lengths and Distances (in Å) between Hydrogen Bonding Atoms in the Active Site of Oxidized IspH as Computed by Geometry Optimizations of Different Protonation Conformers^a.

	exp³²	RO^–P^–E^H	RO^–P^HE^H	RO^HP^–E^–	RO^HP^HE^–	RO^HP^–E^H	RO^HP^HE^H
HMBPP distances
Fe1–O_C4	2.046	1.891	1.899	2.108	2.133	2.214	2.254
Fe1–C2	2.913	3.136	3.107	3.267	3.266	3.272	3.220
Fe1–C3	3.039	3.497	3.406	3.627	3.551	3.531	3.399
active site H-bonds
O_C4–O_Thr	2.702	3.203	3.182	2.816	2.914	3.189	3.179
O_Thr–O_Glu	2.761	2.628	2.639	2.770	2.771	2.661	2.667
O_Glu–O_W1	2.578	3.618	3.745	3.133	2.907	3.687	3.711
O_W1–O_PPi	2.548	2.723	2.858	2.746	3.006	2.734	2.836
RMSD		0.57	0.59	0.40	0.40	0.57	0.58

O_C4 refers to the oxygen attached to C4 on HMBPP, O_T167 refers to the T167 hydroxyl oxygen, O_E126 refers to the E126 carboxylate oxygen directed inward toward the active site, O_W1 is a conserved active site water, and O_{PP_i} is the oxygen on the PP_i group that interacts with W1. For comparison, the corresponding distances from the IspH:HMBPP crystal structure are given,³² and the state computed to have the best agreement with each geometric parameter from experiment is set in bold-type font.³² The root–mean–square deviation (RMSD, given in Å) between different protonation conformers computed for oxidized IspH and the IspH:HMPP crystal structure are tabulated.

Table 3. Key HMBPP Bond Lengths and Distances (in Å) between Hydrogen Bonding Atoms in the Active Site of Oxidized IspH as Computed by Geometry Optimizations of Different Protonation Conformersa.

Table 3. Key HMBPP Bond Lengths and Distances (in Å) between Hydrogen Bonding Atoms in the Active Site of Oxidized IspH as Computed by Geometry Optimizations of Different Protonation Conformers^a.