Closset J, Gerday C
Biochim Biophys Acta. 1975 Oct 20;405(2):228-35. doi: 10.1016/0005-2795(75)90089-6.
Structural variations of two parvalbumins, Whiting III and Pike III, in various denaturing conditions, have been studied by circular dichroism. CD signals are depressed from 4 urea. For Pike III, acidic pH, sodium dodecyl sulfate or complete removal of Ca2+ show little effect in the far ultraviolet region but rather strong effects in the near ultraviolet. For Whiting III similar results are obtained at acidic pH. Carboxymethylated Whiting III (0.15 Ca2+/mol) shows, on the contrary, decreased CD signals in the far and in the near ultraviolet spectra. Addition of Ca2+ fully restores the native CD spectra in both proteins. Ca2+ binding produces structural modifications which are found to vary according to parvalbumin and which seem in any case different from those described for troponin C.
