Unfolding-refolding behaviour of chicken egg white ovomucoid and its correlation with the three domain structure of the protein.


The urea and heat-induced unfolding-refolding behaviours of chicken egg white ovomucoid and its four fragments representing domains I, II + III, I + II and III were systematically investigated in 0.06 M sodium phosphate buffer (pH 7.0) by difference spectral measurements. The effect of temperature on ovomucoid and its fragments was also studied in 0.05 M sodium acetate buffer (pH 5.0) and in presence of 2 M urea at pH 7.0. Intrinsic viscosity data showed that ovomucoid and its different fragments did not lose any significant amount of their structure under mild acidic conditions (pH 4.6). Difference spectral results showed extensive disruption of the native structure by urea or temperature. Isothermal transitions showed single-step for domain I, domain I + II and domain III, and two-step having one stable intermediate, for ovomucoid and its fragment representing domain II + III. However, the presence of intermediate was not detected when the transitions were studied with temperature at pH 7.0. Strikingly, the single-step thermal transitions of ovomucoid and its fragment representing domain II + III, became two-step when measured either at pH 5.0 or in presence of 2 M urea at pH 7.0. Analysis of the equilibrium data on urea and heat denaturation showed that the second transition observed with ovomucoid or domain II + III represent the unfolding of domain III. The kinetic results of ovomucoid and its fragments indicate that the protein unfolds with three kinetic phases. A comparison of three rate constants for the unfolding of intact ovomucoid with that of its various fragments revealed that domain I, II and III of the protein correspond to the three kinetic phases having rate constants 0.456, 0.120 and 0.054 min-1, respectively. These data have led us to conclude: (i) the unusual stability of ovomucoid towards various denaturants, including temperature, is due to its domain III, (ii) initiation of the folding of the ovomucoid molecule starts from its NH2-terminal region which probably provides the nucleation site for the formation of the subsequent structure and (iii) domains I and II have greater mutual recognition between them as compared to the recognition either of them have with domain III. Study holds ProTherm entries: 10079 Extra Details: transition II ovomucoid; egg-white trypsin inhibitor; structual domain;,conformation; equilibrium studies; kinetic studies; protein denaturation

Submission Details

ID: oPTrcoqS

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:39 p.m.

Version: 1

Publication Details
Das BK;Agarwal SK;Khan MY,Biochim. Biophys. Acta (1991) Unfolding-refolding behaviour of chicken egg white ovomucoid and its correlation with the three domain structure of the protein. PMID:2001382
Additional Information

Study Summary

Number of data points 1
Proteins Ovomucoid ; Ovomucoid
Unique complexes 1
Assays/Quantities/Protocols Experimental Assay: dHvH

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 P01005 IOVO_CHICK
98.2 Ovomucoid P52267 IOVO_GALVA
94.6 Ovomucoid P05598 IOVO_FRAPO
96.4 Ovomucoid P52258 IOVO_AFRCO
98.2 Ovomucoid P05609 IOVO_PAVCR
96.4 Ovomucoid P52261 IOVO_LOPBU
91.1 Ovomucoid P52259 IOVO_BAMTH
98.2 Ovomucoid P67957 IOVO_CATWA
98.2 Ovomucoid P67945 IOVO_CENUR
98.2 Ovomucoid P67951 IOVO_CROAU
100.0 Ovomucoid P52245 IOVO_CROCS
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
100.0 Ovomucoid P68436 IOVO_MELOE
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 P05589 IOVO_CALSC
96.4 Ovomucoid P68128 IOVO_CHRAM
96.4 Ovomucoid P68127 IOVO_CHRPC
98.1 Ovomucoid P52263 IOVO_PAVMU
94.5 Ovomucoid P05588 IOVO_CALSP
96.4 Ovomucoid P52262 IOVO_LOPLE
94.6 Ovomucoid P05599 IOVO_PERPE
98.2 Ovomucoid P68387 IOVO_CALCC
98.2 Ovomucoid P68388 IOVO_CALGM
94.6 Ovomucoid P05585 IOVO_BONUM
94.6 Ovomucoid P67893 IOVO_LOPDI
94.6 Ovomucoid P67894 IOVO_LOPIG
94.6 Ovomucoid P05605 IOVO_SYRRE
96.4 Ovomucoid P05592 IOVO_CYRMO
96.4 Ovomucoid P05587 IOVO_OREPI
96.3 Ovomucoid P52269 IOVO_SYRMI
94.5 Ovomucoid P05591 IOVO_COLVI
96.2 Ovomucoid P68146 IOVO_ALECH
96.2 Ovomucoid P68147 IOVO_ALERU
94.2 Ovomucoid P68469 IOVO_ACRVU
94.2 Ovomucoid P68468 IOVO_NUMME
100.0 Ovomucoid P68390 IOVO_MELGA
92.9 Ovomucoid P68470 IOVO_PHACO
92.9 Ovomucoid P68471 IOVO_PHAVE
92.7 Ovomucoid P05596 IOVO_PTEER
92.5 Ovomucoid P05601 IOVO_ARBTO
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