Conformational changes in the bilirubin-human serum albumin complex at extreme alkaline pH.
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ABSTRACT: Light-absorption, c.d. and fluorescence of the bilirubin-albumin complex were investigated at extreme alkaline pH. Above pH 11.1 albumin binds the bilirubin molecule, twisted oppositely to the configuration at more neutral pH. On the basis of light-absorption it is shown that two alkaline transitions occur. The first alkaline transition takes place at pH between 11.3 and 11.8, co-operatively dissociating at least six protons. The second alkaline transition takes place at pH between 11.8 and 12.0. It probably implies a reversible unfolding of the albumin molecule, increasing the distance between tryptophan-214 and bilirubin, and partly exposing the liganded bilirubin to the solvent.
SUBMITTER: Honore B
PROVIDER: S-EPMC1146849 | biostudies-other | 1986 Jun
REPOSITORIES: biostudies-other
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