Spin label studies of the essential sulfhydryl group environment in chicken liver fructose-1,6-bisphosphatase |
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Authors: | H Zeidan P Han J Johnson |
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Abstract: | The local environment of the essential sulfhydryl groups in chicken liver fructose-1,6-bisphosphatase has been investigated by ESR techniques using a series of iodoacetamide spin labels, varying in chain length between the iodoacetate and nitroxide free radical group. The ESR spectrum of spin-labeled chicken liver fructose-1,6-bisphosphatase showed that the sites of labeling were highly immunobilized when the enzyme was chemically modified by spin label iodoacetate, suggesting that the sulfhydryl groups of the protein are in a small, confined environment. From the change in the ESR spectra of these nitroxides as a function of chain length, we conclude that the sulfhydryl group is located in a cleft approx. 10.5A in depth. |
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