TY - JOUR

T1 - NMR Studies of Active Site Properties of Human Carbonic Anhydrase II using 15N labeled 4-Methylimidazole as a Local Probe and Histidine Hydrogen Bond Correlations

AU - Shenderovich, Ilya G.

AU - Lesnichin, Stepan B.

AU - Tu, Chingkuang

AU - Silverman, David N.

AU - Tolstoy, Peter M.

AU - Denisov, Gleb S.

AU - Limbach, Hans-Heinrich

PY - 2015

Y1 - 2015

N2 - By using a combination of liquid and solid-state NMR spectroscopy, N-15-labeled 4-methylimidazole (4-MI) as a local probe of the environment has been studied: 1) in the polar, wet Freon CDF3/CDF2Cl down to 130 K, 2) in water at pH 12, and 3) in solid samples of the mutant H64A of human carbonic anhydrase II (HCA II). In the latter, the active-site His64 residue is replaced by alanine; the catalytic activity is, however, rescued by the presence of 4-MI. For the Freon solution, it is demonstrated that addition of water molecules not only catalyzes proton tautomerism but also lifts its quasidegeneracy. The possible hydrogen-bond clusters formed and the mechanism of the tautomerism are discussed. Information about the imidazole hydrogen-bond geometries is obtained by establishing a correlation between published H-1 and N-15 chemical shifts of the imidazole rings of histidines in proteins. This correlation is useful to distinguish histidines embedded in the interior of proteins and those at the surface, embedded i

AB - By using a combination of liquid and solid-state NMR spectroscopy, N-15-labeled 4-methylimidazole (4-MI) as a local probe of the environment has been studied: 1) in the polar, wet Freon CDF3/CDF2Cl down to 130 K, 2) in water at pH 12, and 3) in solid samples of the mutant H64A of human carbonic anhydrase II (HCA II). In the latter, the active-site His64 residue is replaced by alanine; the catalytic activity is, however, rescued by the presence of 4-MI. For the Freon solution, it is demonstrated that addition of water molecules not only catalyzes proton tautomerism but also lifts its quasidegeneracy. The possible hydrogen-bond clusters formed and the mechanism of the tautomerism are discussed. Information about the imidazole hydrogen-bond geometries is obtained by establishing a correlation between published H-1 and N-15 chemical shifts of the imidazole rings of histidines in proteins. This correlation is useful to distinguish histidines embedded in the interior of proteins and those at the surface, embedded i

U2 - 10.1002/chem.201404083

DO - 10.1002/chem.201404083

M3 - Article

VL - 21

SP - 2915

EP - 2929

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 7

ER -