title: Unfolding and refolding of phospholipase C from Bacillus cereus in solutions of guanidinium chloride.
abstract: 1. Protein-fluorescence studies indicated that phospholipase C from Bacillus cereus is denatured in solutions of guanidinium chloride. The denaturation was not thermodynamically reversible and followed biphasic kinetics. 2. Guanidinium chloride solutions released the structural Zn2+ from the enzyme and rendered all histidine residues chemically reactive. In the presence of free Zn1+ the enzyme was much more resistant to denaturation. Also, the addition for free Zn2+ to the denatured enzyme induced refolding. 3. The Zn2+-free apoenzyme was much more sensitive to guanidinium chloride than was the native enzyme and the denaturation appeared to be thermodynamically reversible. 4. Guanidinium chloride denaturation was associated with a reversible inactivation of the enzyme. Heat-inactivated, coagulated enzyme was substantially re-activated on dissolution in guanidinium chloride solutions followed by dialysis against a Zn2+-containing buffer.
mesh_terms: D001051:Apoenzymes; D001409:Bacillus cereus / Q000201:enzymology*; D006146:Guanidines; D006358:Hot Temperature; D007700:Kinetics; D010740:Phospholipases; D011487:Protein Conformation; D011489:Protein Denaturation / Q000187:drug effects; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000032:analysis / Q000494:pharmacology
chemical_list: D001051:Apoenzymes; D006146:Guanidines; D010740:Phospholipases; D015032:Zinc