[Protein globule without the unique three-dimensional structure: experimental data for alpha-lactalbumins and general model].
It has been shown that 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 the bound to it 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 three-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.
D000818:Animals; D002417:Cattle; D019791:Guanidine; D006146:Guanidines; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007768:Lactalbumin; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
D006146:Guanidines; D007768:Lactalbumin; D019791:Guanidine
Belkovye globuly bez unikal'noĭ prostranstvennoĭ struktury: eksperimental'nye dannye dlia al'fa-laktal'buminov i obshchaia model'.