title: Microenvironment around the essential cysteine residues in chicken liver fructose-1,6-bisphosphatase as analyzed by ESR spin labelling.
abstract: Chemical modification and electron spin resonance spectroscopy (ESR) spin-labelling techniques have been employed to investigate the local environment of the essential sulfhydryl groups of chicken liver fructose-1,6-bisphosphatase. The results demonstrate the presence of two distinct classes of sulfhydryl groups in this enzyme. The first class react preferentially with iodoacetate and its spin-labelled derivative, and this results in an increase in catalytic activity, while the second class react preferentially with N-ethylmaleimide and its spin-labelled derivative, and this leads to a decrease in catalytic activity. The ESR spectral data strongly suggest that the first class of sulfhydryl groups are located in a deep cleft of the enzyme molecule, while the second class of sulfhydryl groups are located in a shallow crevice. The environment of the second class of the sulfhydryl groups appears to undergo a significant change after the modification of the first class of sulfhydryl groups by iodoacetate.
mesh_terms: D000818:Animals; D002645:Chickens; D003545:Cysteine / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005033:Ethylmaleimide / Q000378:metabolism; D006597:Fructose-Bisphosphatase / Q000032:analysis*; D007461:Iodoacetates / Q000378:metabolism; D019807:Iodoacetic Acid; D008099:Liver / Q000201:enzymology; D011487:Protein Conformation; D013113:Spin Labels / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D007461:Iodoacetates; D013113:Spin Labels; D013438:Sulfhydryl Compounds; D006597:Fructose-Bisphosphatase; D003545:Cysteine; D005033:Ethylmaleimide; D019807:Iodoacetic Acid