INOR 194 |
| The crystal structure of horseradish peroxidase (HRP) reveals two bound Ca2+ ions possibly required for catalysis and protein stability. We investigate acid-induced conformational changes in Ca2+-bound and Ca2+-depleted HRP by monitoring heme Soret absorbance. Soret band spectral changes at acidic pH over time depend on the anion present in solution. Upon dissolving Ca2+-bound HRP in water adjusted to pH 3 with HCl, the Soret band remained unchanged. In 50 mM phosphate buffer adjusted to pH 3 with HCl, the Soret band rapidly shifted from 403 nm to 370 nm. Phosphate amplifies acid-induced conformational changes in HRP. To investigate the role of Ca2+ in acid-induced conformational changes, Ca2+-depleted HRP was prepared. Surprisingly, acid-induced conformational changes in Ca2+-depleted HRP were similar to those in Ca2+-bound HRP. Acid-induced conformational changes in HRP appear to be more dependent on the anion than on the presence or absence of bound Ca2+. |
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The Bioinorganic Chemistry Relating to Enzymes and Proteins
7:00 PM-10:00 PM, Sunday, March 25, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Sci-Mix
Division of Inorganic Chemistry |