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Salt‐induced folding of alkaline denatured creatine kinase under high pH conditions
Author(s) -
Yang HaiPeng,
Zhong HaiNing,
Li Sen,
Zhou HaiMeng
Publication year - 1997
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549700201261
Subject(s) - chemistry , circular dichroism , molten globule , salt (chemistry) , ionic strength , folding (dsp implementation) , protein folding , native state , crystallography , protein secondary structure , tryptophan , fluorescence , creatine kinase , aqueous solution , biophysics , biochemistry , amino acid , physics , quantum mechanics , electrical engineering , biology , engineering
The conformational changes of creatine kinase during alkaline unfolding and salt‐induced folding at high pH have been followed by fluorescence emission and circular dichroism spectra. The results obtained show that at low ionic strength, with increasing pH value, creatine kinase denatured gradually to reach the ultimate unfolded conformation in the vicinity of pH 12.7. With the increase of pH from 9.0 to 12.7, the fluorescence emission maximum red shifted from 337 to 355 nm, indicating complete exposure of the buried tryptophan residues to the solvent. The far‐UV CD spectra show that even at pH 12.7, the apparently fully denatured enzyme retains a great part of ordered secondary structure. At pH 12.7 by adding the salt, the relatively unfolded state of denatured enzyme changes into a compact conformational state by hydrophobic collapsing. Folded state induced by salt bound ANS strongly, indicating the existence of increased hydrophobic surface. The above results suggest that the salt‐induced folded state at high pH may be the folded intermediate which exists in the general protein folding, and the larger residual ordered secondary structure might become folded being point on the salt‐induced folding.