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Physical nature of the phase transition in globular proteins
Author(s) -
Pfeil Wolfgang,
Bychkova Valentina E.,
Ptitsyn Oleg B.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80422-7
Subject(s) - globular cluster , globular protein , phase transition , transition (genetics) , chemistry , biophysics , physics , crystallography , biology , astrophysics , biochemistry , thermodynamics , galaxy , gene
The guanidine hydrochloride‐induced unfolding of human α‐lactalbumin has been studied by isothermal calorimetry. It has been shown that a cooperative transition takes place only in the concentration interval of the denaturant between 0.3 and 2 mol · 1 −1 . The cooperative transition coincides with the transition detected by circular dichroism in the near‐ultraviolet region which reflects the destruction of the specific environment of aromatic side groups. According to scanning calorimetric investigations, the transition disappears in the acid form of the protein where circular dichroism of aromatic side groups is practically absent. At higher concentrations of guanidine hydrochloride, where destruction of the secondary structure and un‐ folding of the chain are observed, there is no cooperative heat absorption.