Effects of aspartate on rabbit muscle creatine kinase and the salt induced molten globule state.
The aspartate (Asp)-induced unfolding and the salt-induced folding of creatine kinase (CK) have been studied by measuring enzyme activity, fluorescence emission spectra, circular dichroism (CD) spectra, native polyacrylamide gel electrophoresis and ultraviolet difference spectra. The results showed that Asp caused inactivation and unfolding of CK, with no aggregation during CK denaturation. The kinetics of CK unfolding followed a one phase process. At higher concentrations of Asp (>2.5mM), the CK dimers were partially dissociated. Inactivation occurred before noticeable conformational change during CK denaturation. Asp denatured CK was mostly reactivated and refolded by dilution. KCl induced the molten globule state with compact structure after CK was denatured with 10mM Asp. These results suggest that the effect of Asp differed from that of other denaturants such as guanidine, HCl or urea during CK unfolding. Asp is a reversible protein denaturant and the molten globule state indicates that intermediates exist during CK folding.
Ou
Wen bin
Wb
Department of Biological Science and Biotechnology, Tsinghua University, Beijing, PR China.
Wang
Ri Sheng
RS
Lu
Jie
J
Zhou
Hai Meng
HM
D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology*; D003402:Creatine Kinase / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D052283:Creatine Kinase, MM Form; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D007527:Isoenzymes / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D007700:Kinetics; D011189:Potassium Chloride / Q000494:pharmacology*; D011489:Protein Denaturation; D017510:Protein Folding; D020673:Protein Renaturation; D011817:Rabbits; D012996:Solutions
D007527:Isoenzymes; D012996:Solutions; D001224:Aspartic Acid; D011189:Potassium Chloride; D003402:Creatine Kinase; D052283:Creatine Kinase, MM Form