Hydrogen bonds and the pH dependence of ovomucoid third domain stability.


Thermal denaturation of turkey ovomucoid third domain (OMTKY3) has been monitored with differential scanning calorimetry (DSC) and circular dichroism in H2O and D2O, pH 1.5 to 5 and ionic strength 0.01 to 0.71. Results from DSC experiments are in good agreement with spectroscopic studies [Swint, L., & Robertson, A.D. (1993) Protein Sci. 2, 2037-2049] and fit well to the two-state unfolding model. The average ratio of calorimetric to van't Hoff enthalpies is 0.99 +/- 0.03 (n = 16), and the average value of delta Cp is 620 +/- 20 cal/(mol K) (n = 7). The free energy of unfolding (delta G(u)o) increases in the presence of salt at both pH 1.5 and 4.5. This stabilization is not due to ion binding and probably results from screened repulsive interactions between the cationic groups of OMTKY3. At very low ionic strength, the change in delta G(u)o from pH 1.5 to 4.5, delta delta GpHo, is 3.5 +/- 0.2 kcal/mol. Few interactions between ionizing groups are affected by the addition of 200 mM KCl; delta delta GpHo decreases by only 0.4 +/- 0.3 kcal/mol. Comparison of delta delta GpHo with values calculated from the pKas of all six carboxyl groups in OMTKY3 [Schaller, W.S., & Robertson, A.D. (1995) Biochemistry 34, 4714-4723] suggests that some pKas in the denatured state may be lower than those of model compounds. Moreover, calculated values of delta delta GpHo are very sensitive to modest changes in the cooperativity of proton binding.(ABSTRACT TRUNCATED AT 250 WORDS) Study holds ProTherm entries: 5043, 5044, 5045, 5046, 5047, 5048, 5049, 5050, 5051, 5052, 5053, 5054, 5055, 5056 Extra Details:

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:28 p.m.

Version: 1

Publication Details
Swint-Kruse L;Robertson AD,Biochemistry (1995) Hydrogen bonds and the pH dependence of ovomucoid third domain stability. PMID:7718578
Additional Information

Study Summary

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Ovomucoid P52245 IOVO_CROCS
100.0 Ovomucoid P68390 IOVO_MELGA
100.0 Ovomucoid P68436 IOVO_MELOE
98.2 Ovomucoid P67957 IOVO_CATWA
98.2 Ovomucoid P67945 IOVO_CENUR
98.2 Ovomucoid P67951 IOVO_CROAU
98.2 Ovomucoid P67952 IOVO_CROMA
98.2 Ovomucoid P67961 IOVO_LAGLU
98.2 Ovomucoid P67953 IOVO_LOPED
98.2 Ovomucoid P67950 IOVO_LOPIM
98.2 Ovomucoid P67954 IOVO_LOPNY
98.2 Ovomucoid P67955 IOVO_LOPSW
98.2 Ovomucoid P67956 IOVO_PUCMA
98.2 Ovomucoid P67958 IOVO_SYREL
98.2 Ovomucoid P67959 IOVO_SYRHU
98.2 Ovomucoid P67960 IOVO_SYRSO
98.2 Ovomucoid P67946 IOVO_TRABL
98.2 Ovomucoid P67947 IOVO_TRACA
98.2 Ovomucoid P67948 IOVO_TRASA
98.2 Ovomucoid P67949 IOVO_TRATE
98.2 Ovomucoid P67944 IOVO_TYMCU
96.4 Ovomucoid P68128 IOVO_CHRAM
96.4 Ovomucoid P68127 IOVO_CHRPC
98.2 Ovomucoid P05609 IOVO_PAVCR
96.4 Ovomucoid P52261 IOVO_LOPBU
96.4 Ovomucoid P52262 IOVO_LOPLE
96.4 Ovomucoid P52258 IOVO_AFRCO
98.2 Ovomucoid P68387 IOVO_CALCC
98.2 Ovomucoid P68388 IOVO_CALGM
94.6 Ovomucoid P05599 IOVO_PERPE
94.6 Ovomucoid P05585 IOVO_BONUM
94.6 Ovomucoid P67893 IOVO_LOPDI
94.6 Ovomucoid P67894 IOVO_LOPIG
98.1 Ovomucoid P52263 IOVO_PAVMU
96.4 Ovomucoid P05592 IOVO_CYRMO
94.6 Ovomucoid P05605 IOVO_SYRRE
96.4 Ovomucoid P05587 IOVO_OREPI
96.4 Ovomucoid P05589 IOVO_CALSC
92.9 Ovomucoid P68470 IOVO_PHACO
92.9 Ovomucoid P68471 IOVO_PHAVE
96.3 Ovomucoid P52269 IOVO_SYRMI
94.5 Ovomucoid P05588 IOVO_CALSP
94.6 Ovomucoid P01005 IOVO_CHICK
92.7 Ovomucoid P05596 IOVO_PTEER
96.2 Ovomucoid P68146 IOVO_ALECH
96.2 Ovomucoid P68147 IOVO_ALERU
94.5 Ovomucoid P05591 IOVO_COLVI
92.9 Ovomucoid P05598 IOVO_FRAPO
92.5 Ovomucoid P05601 IOVO_ARBTO
92.9 Ovomucoid P52267 IOVO_GALVA
94.2 Ovomucoid P68469 IOVO_ACRVU
94.2 Ovomucoid P68468 IOVO_NUMME
92.5 Ovomucoid P05594 IOVO_PTEAF
92.3 Ovomucoid P67890 IOVO_DENAC
92.3 Ovomucoid P67889 IOVO_DENAR
92.3 Ovomucoid P67891 IOVO_DENAU
92.3 Ovomucoid P67892 IOVO_DENBI
90.4 Ovomucoid P68129 IOVO_CYGAT
90.4 Ovomucoid P68130 IOVO_CYGOL
90.4 Ovomucoid P68131 IOVO_OXYJA
90.4 Ovomucoid P68132 IOVO_OXYVI
90.6 Ovomucoid P05595 IOVO_PELCO
90.4 Ovomucoid P68394 IOVO_ANSCA
90.4 Ovomucoid P68393 IOVO_BRACA
90.4 Ovomucoid P05570 IOVO_DENVD
90.4 Ovomucoid P05571 IOVO_COSCO
90.4 Ovomucoid P52260 IOVO_GUTPU
90.4 Ovomucoid P05567 IOVO_ANSSE