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Published March 2015 | metadata_only
Journal Article

Could tyrosine and tryptophan serve multiple roles in biological redox processes?


Single-step electron tunnelling reactions can transport charges over distances of 15–20 Å in proteins. Longer-range transfer requires multi-step tunnelling processes along redox chains, often referred to as hopping. Long-range hopping via oxidized radicals of tryptophan and tyrosine, which has been identified in several natural enzymes, has been demonstrated in artificial constructs of the blue copper protein azurin. Tryptophan and tyrosine serve as hopping way stations in high-potential charge transport processes. It may be no coincidence that these two residues occur with greater-than-average frequency in O_2- and H_2O_2-reactive enzymes. We suggest that appropriately placed tyrosine and/or tryptophan residues prevent damage from high-potential reactive intermediates by reduction followed by transfer of the oxidizing equivalent to less harmful sites or out of the protein altogether.

Additional Information

© 2015 The Author(s). Published by the Royal Society. Published 9 February 2015. Our work on biological electron transfer processes is supported by the National Institutes of Health (DK-019038) and the Arnold and Mabel Beckman Foundation.

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August 20, 2023
August 20, 2023