Conformational stability of bovine holo and apo adrenodoxin--a scanning calorimetric study.


Abstract

Holo and apo adrenodoxin were studied by differential scanning calorimetry, absorption spectroscopy, limited proteolysis, and size-exclusion chromatography. To determine the conformational stability of adrenodoxin, a method was found that prevents the irreversible destruction of the iron-sulfur center. The approach makes use of a buffer solution that contains sodium sulfide and mercaptoethanol. The thermal transition of adrenodoxin takes place at Ttrs = 46-57 degrees C, depending on the Na2S concentration with a denaturation enthalpy of delta H = 300-380 kJ/mol. From delta H versus Ttrs a heat capacity change was determined as delta Cp = 7.5 +/- 1.2 kJ/mol/K. The apo protein is less stable than the holo protein as judged by the lower denaturation enthalpy (delta H = 93 +/- 14 kJ/mol at Ttrs = 37.4 +/- 3.3 degrees C) and the higher proteolytic susceptibility. The importance of the iron-sulfur cluster for the conformational stability of adrenodoxin and some conditions for refolding of the thermally denatured protein are discussed. Study holds ProTherm entries: 7246, 7247, 7248, 7249, 7250, 7251 Extra Details: Na2S(10 mM) and ascorbic acid(1 mM) were added in the experiment ferredoxin; iron-sulfur protein; protein unfolding;,scanning microcalorimetry; thermodynamics

Submission Details

ID: czRsAPJd

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:33 p.m.

Version: 1

Publication Details
Burova TV;Bernhardt R;Pfeil W,Protein Sci. (1995) Conformational stability of bovine holo and apo adrenodoxin--a scanning calorimetric study. PMID:7663346
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