Intermediates in guanidine-HC1 unfolding of glutamine synthetase from the extreme thermophile, Bacillus caldolyticus.
Glutamine synthetase is expressed in Bacillus caldolyticus as two isoforms that differ in physico-chemical and regulatory properties. Biphasic kinetics of thermal denaturation of E-I and E-II (Merkler, D.J., et al (1987) Biochemistry 26, 7805), suggested the formation of intermediates. CD spectral changes of E-II induced by guanidine-HC1 clearly indicate a three-state pathway for unfolding (N----I----D). Refolding of E-II from 6 M GuHCl led to only 15% recovery of activity, compared to greater than or equal to 90% with E-I.
Wedler
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Department of Molecular and Cell Biology, Althouse Laboratory, Pennsylvania State University, University Park 16802.
McLean
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D001407:Bacillus / Q000201:enzymology*; D002942:Circular Dichroism; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry*; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology*; D007700:Kinetics; D011487:Protein Conformation; D011489:Protein Denaturation; D013696:Temperature
D006146:Guanidines; D005974:Glutamate-Ammonia Ligase; D019791:Guanidine