A STUDY ON THE FOLDING OF CREATINE KINASES FROM HUMAN AND RABBIT MUSCLE AT LOW pH
人肌和兔肌肌酸激酶在低pH条件下再折叠的研究

The confonnational stabal of cleatjne the from human and rabbit muscle at acidic pHun examined by the intrinsic proch fluoascence and far--ultlaviolet cellular dichIDism(far--UV CD). The adults we obtained show that at low iohic singtin, by adding HCl, tonative ha and rabbit creatine kinals ash proteins tended to adopt almost an fillly tmfolded confonnational state in the vicely of PH 2.0. Their tryptophan fluorescenceemission had a lhawh at the indicating a complete exposure of the nyptophan asiduesto the solvent. Thed far--UV CD spectla shoal partly disonled secondary str uperthg, butthe se dena Proteins retained soak secondary strucks. However, at high ionic strength andlow PH an in inte confonnational state (molten-globule state) which was fnSt discoverby Goto et al un also olived in our pat experiment . This intointe had a secondary thestructute similar to that of the nahve enzyme. The tryptophan fluorescence spectla were similar,with a mhanum at 335nm to that of the native on, indicating that the protein is almostrefolded complmp. Hoal, the intenSity of fluorescence elnjssion was much lower than thato f native enzyme, indicating that this state is more mobile and adulting in dynamicfluo quenching. The present adults support Goto's discovery. It is suggeStal thatmolten-globule state opt be an nounal folding lute-iate state of proteins.