4714
Biochemistry 1995, 34, 4714-4723
pH, Ionic Strength, and Temperature Dependences of Ionization Equilibria for the Carboxyl Groups in Turkey Ovomucoid Third Domaint Wolfgang Schaller and Andrew D. Robertson* Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242 Received August 29, 1994; Revised Manuscript Received Januaq 19, 1995@
ABSTRACT: Two-dimensional NMR spectroscopy has been used to monitor the pH dependences of proton chemical shifts for turkey ovomucoid third domain (OMTKY3). Sample pH was varied from 7.0 to 1.4 in order to determine the apparent pKa values of all six carboxyl groups in OMTKY3. At 35 "C and in the presence of 10 mM KC1, the PKa values for Asp 7, Glu 19, and Asp 27 (
