Open AccessX-ray absorption studies of halide binding to carbonic anhydrase.
Author(s) -
G. S. Brown,
Gil Navon,
R. G. Shulman
Publication year - 1977
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.74.5.1794
Subject(s) - iodide , carbonic anhydrase , chemistry , absorption (acoustics) , zinc , bromide , halide , carbonic anhydrase ii , zinc bromide , crystallography , inorganic chemistry , enzyme , biochemistry , optics , organic chemistry , physics
X-ray absorption measurements of bovine carbonic anhydrase B have been made at the the Stanford Synchrotron Radiation Project with a spectrometer operating in the fluorescence mode. Differences in absorption at and beyond the zinc K-edge near 9664 ev have been observed upon the addition of bromide or iodide. The additional absorption in k space, out to k approximately 7 A-1, obtained upon the addition of iodide has been compared with the absorption in this region of a ZnI2 sample. The similarities between these absorptions lead to the conclusion that the zinc-iodide distance in the protein is 2.65 +/-0.06 A; it is known to be 2.62 A in ZnI2. This shows that the iodide binds directly to the zinc in the protein.