PROTEIN GLOBULES WITHOUT UNIQUE SPATIAL STRUCTURE - EXPERIMENTAL-DATA FOR ALPHA-LACTALBUMINS AND GENERAL-MODEL

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 27  (6) , 1005-1016
Abstract
Bovine and human .alpha.-lactalbumins under the influence of acidic pH, high temperatures or low guanidine hydrochloride concentrations are transferred into a state which is quite distinct both from the native and the completely denatured (unfolded) ones. Human .alpha.-lactalbumin can be transferred into this intermediate state also by removal of bound Ca2+ ion. On the basis of the obtained physical characteristics of this state a model of the intermediate state is suggested in which a protein globule is compact, has a secondary structure, but does not possess a unique 3-dimensional structure. Phase diagrams of the protein molecule states (native, intermediate and unfolded) are presented and discussed and the role of the intermediate state in protein folding is considered.