Thermodynamic investigations of cytochrome b5 unfolding. I. The tryptic fragment of cytochrome b5.


Thermal unfolding of the tryptic fragment of the membrane-bound protein, cytochrome b5, which contains the residues 1-90, was investigated by scanning calorimetry, circular dichroism and absorption spectroscopy. The fragment undergoes a reversible two-state transition at about 70 degrees C (neutral pH). The fragment exhibits all the thermodynamic properties of small globular proteins with respect to heat capacity and transitional changes of enthalpy, Gibbs energy and heat capacity. The heat capacity change at unfolding fits into the correlation with the specific amount of nonpolar contacts, which has been found to be valid for small globular proteins (Privalov, P.L. and Khechinashvili, N.N. (1974) J. Mol. Biol. 86, 665-684). The relatively low stabilization energy of the cytochrome b5 fragment (delta trsG25 degrees C = 25 kJ/mol) is discussed in terms of the functional requirements of electron-transfer proteins. Study holds ProTherm entries: 11523, 11524 Extra Details: fragment contains the residues 1-90 membrane-bound protein; two-state transition; nonpolar contacts;,electron-transfer proteins

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:42 p.m.

Version: 1

Publication Details
Pfeil W;Bendzko P,Biochim. Biophys. Acta (1980) Thermodynamic investigations of cytochrome b5 unfolding. I. The tryptic fragment of cytochrome b5. PMID:7459384
Additional Information

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 Cytochrome b5 P00169 CYB5_RABIT
93.6 Cytochrome b5 P00170 CYB5_HORSE
91.5 Cytochrome b5 P00173 CYB5_RAT
92.6 Cytochrome b5 P00167 CYB5_HUMAN
90.4 Cytochrome b5 P56395 CYB5_MOUSE
93.1 Cytochrome b5 P00168 CYB5_ALOSE
93.6 Cytochrome b5 P00172 CYB5_PIG
90.3 Cytochrome b5 P00171 CYB5_BOVIN