High-precision measurement of hydrogen bond lengths in proteins by nuclearmagnetic resonance methods

We have compared hydrogen bond lengths on enzymes derived with high precisi on (less than or equal to +/-0.05 Angstrom) from both the proton chemical s hifts (delta) and the fractionation factors (phi) of the proton involved wi th those obtained from protein X-ray crystallography. Hydrogen bond distanc es derived from proton chemical shifts were obtained from a correlation of 59 O-H ... O hydrogen bond lengths, measured by small molecule high-resolut ion X-ray crystallography, with chemical shifts determined by solid-state n uclear magnetic resonance (NMR) in the same crystals (McDermott A, Ridenour CF, Encyclopedia of NMR, Sussex, U.K.: Wiley, 1996:3820-3825), Hydrogen bo nd distances were independently obtained from fractionation factors that yi eld distances between the two proton wells in quartic double minimum potent ial functions (Kreevoy MM, Liang TM, J Am Chem Soc, 1980;102:3315-3322), Th e high-precision hydrogen bond distances derived from their corresponding N MR-measured proton chemical shifts and fractionation factors agree well wit h each other and with those reported in protein X-ray structures within the larger errors (+/-0.2-0.8 Angstrom) in distances obtained by protein X-ray crystallography. The increased precision in measurements of hydrogen bond lengths by NMR has provided insight into the contributions of short, strong hydrogen bonds to catalysis for several enzymatic reactions. (C) 1999 Wile y-Liss, Inc.