The glycophosphatidylinositol anchor oppositely affects unfolding and refolding of alkaline phosphatase.
Regarding the world wide success of artificial chaperone-assisted protein refolding technique and based on its well worked-out mechanism, it is anticipated that the lipid moieties of glycosylphosphatidylinositol (GPI) group, which is present in some membrane proteins, might interfere with the capturing step of the technique. To find an answer, we evaluated the chemical denaturation and also the refolding behavior of insoluble and soluble alkaline phosohatase (ALP), with or without GPI group, respectively. The results indicated that the presence of GPI in the enzyme increased the stability of the protein against chemical denaturation while it decreased its refolding yield by the artificial chaperone refolding technique. The lower refolding yield, compared to soluble ALP (sALP), might be due to a less efficient stripping step caused by new interactions imparted to the refolding elements of the system especially those among the hydrophobic tails of GPI and the capturing agent of the technique. These new interactions will interrupt the kinetics of detergent stripping from the captured molecules by the stripping agent (i.e., cyclodextrins). This situation will lead to higher intermolecular hydrophobic interactions among the refolding protein intermediates leading to their higher misfolding and aggregation.
Khodagholi
Fariba
F
Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran.
Yazdanparast
Razieh
R
Sadeghirizi
Akram
A
D000469:Alkaline Phosphatase / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004795:Enzyme Stability; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism; D011489:Protein Denaturation; D017510:Protein Folding
D017261:Glycosylphosphatidylinositols; D018832:Molecular Chaperones; D000469:Alkaline Phosphatase