Effect of osmolytes as folding aids on creatine kinase refolding pathway.
The influence of osmolytes, including dimethysulfoxide, glycine, proline and sucrose, on the refolding and reactivation courses of guanidine-denatured creatine kinase was studied by fluorescence emission spectra, circular dichroism spectra, recovery of enzymatic activity and aggregation. The results showed that low concentrations of dimethysulfoxide (<20%), glycine (<0.5 M), proline (<1 M) and sucrose (<0.75 M) improved the refolding yields of creatine kinase, but high osmolyte concentrations decreased its recovery. Sucrose favored the secondary structural formation of creatine kinase. Proline and sucrose facilitated refolding of the protein to its original conformation, while dimethysulfoxide and proline accelerated the hydrophobic collapse of creatine kinase to a packed protein. During the aggregation of creatine kinase, dimethysulfoxide and sucrose inhibited aggregation of creatine kinase, as did proline, but glycine was unable to inhibit aggregation. These systematic observations further support the suggestion that osmolytes, including low concentrations of dimethysulfoxide, proline or sucrose, possibly play a chaperone role in the refolding of creatine kinase. The results also indicate that sucrose and free amino acids are not only energy substrates and organic components in vivo, but also help correct protein folding.
Ou
Wen-Bin
WB
Department of Biological Science and Biotechnology, Tsinghua University, Beijing 100084, People's Republic of China.
Park
Yong-Doo
YD
Zhou
Hai-Meng
HM
D000818:Animals; D002021:Buffers; D002942:Circular Dichroism; D003402:Creatine Kinase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004789:Enzyme Activation; D005998:Glycine / Q000737:chemistry; D009994:Osmolar Concentration; D011392:Proline / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011817:Rabbits; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013395:Sucrose / Q000737:chemistry
D002021:Buffers; D012997:Solvents; D013395:Sucrose; D011392:Proline; D003402:Creatine Kinase; D005998:Glycine; D004121:Dimethyl Sulfoxide