Fractionation factor for hydrogen isotopes at the aqueous ligand of cobalt in Co(II)-substituted bovine carbonic anhydrase

Journal Article · Wed Oct 07 00:00:00 EDT 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00410a055· OSTI ID:5807760

Silverman, D N

The accurate interpretation of the solvent deuterium isotope effect in the hydration of CO/sub 2/ catalyzed by carbonic anhydrase requires a knowledge of the fractionation factor of the reactant state of the enzyme's active site, which is a species of water bound to the metal of carbonic anhydrase. The NMR method of Gold (Gold, V. Proc. Chem. Soc. 1963, 141), (Kresge, A.J.; Allred, A.L.; J. Am. Chem. Soc. 1963, 85, 1541) and Kresge and Allred for the determination of reactant state fractionation factors is based on the chemical shift which results from the rapid exchange of proteins between solute and solvent. When this exchange is sufficiently rapid, a single resonance is observed with chemical shift that is the weighted average of the chemical shift at the solute site and the solvent site in the absence of exchange, information from which a fractionation factor can be obtained. This method has not been applied to proteins because of the complexity of the protein NMR envelope and also because the concentration of proton required to give detectable changes in chemical shifts is so large as to exceed protein solubility or at least to introduce errors from solute-solute interactions. This report demonstrates that these difficulties can be overcome by modifying the method of Gold and Kresge and Allred to use the relaxation rate, 1/T/sub 1/, of the exchanging ligands of a paramagnetic metal in a metalloenzyme, such as cobalt in Co(II)-substituted carbonic anhydrase.

• Research Organization: Univ. of Florida, Gainesville
• OSTI ID: 5807760
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:20; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBON-OXYGEN LYASES
CARBONIC ANHYDRASE
CATALYTIC EFFECTS
CHALCOGENIDES
COBALT COMPLEXES
COMPLEXES
DEUTERIUM
ENZYMES
HYDRATION
HYDRO-LYASES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
LYASES
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
OXIDES
OXYGEN COMPOUNDS
RELAXATION
RESONANCE
SOLVATION
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
WATER