Homologous structural domains in chicken egg-white ovomucoid: Characterization and acid denaturation.
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Date
1985-08
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Abstract
The primary structure of ovomucoid shows considerable sequence homology at
three contiguous regions which form structural domains I, II and III. In order to see whether or
not the three domains fold similarly and acquire similar overall native conformation/shape,
two fragments A and C were obtained by controlled peptic digestion of ovomucoid. The two
fragments were investigated for their chemical composition, molecular weight, anti-tryptic
activity, hydrodynamic behaviour, optical properties and acid denaturation. Results on
molecular weight, amino acid composition and inhibitory acitivity show that the fragments A
and C correspond respectively to domain I-II and domain III. Optical data suggested more
exposure of tyrosine residues in the fragments than in the intact molecule. Domain III exists in
a compact and globular conformation under native conditions whereas domain I-II and
ovomucoid appear to possess asymmetric conformation. Results on acid denaturation show
that the process is thermodynamically reversible and that inter-domain separation probably
precedes denaturation of domains during acidification of ovomucoid.
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Keywords
Ovomucoid, acid denaturation, structural domains, conformation, proteins
Citation
Salahuddin A, Sibghatullah, Baig M A. Homologous structural domains in chicken egg-white ovomucoid: Characterization and acid denaturation. Journal of Biosciences. 1985 Aug; 8(1&2): 67-87.