A possible biological role of the electron transfer between tyrosine and tryptophan. Gating of ion channels.
Experiments have demonstrated that four tryptophan residues are located near the tetrodotoxin binding site in Na+ channels, and that conserved tyrosine and tryptophan residues are located in the pore-forming region of voltage-sensitive K+ channels. This paper proposes an activation mechanism involving electron transfer between these residues. The K+ channel may be closed by four tyrosine residues forming hydrogen bonds with each other. After electron transfer, these hydrogen bonds will be broken, thereby opening the channel. The Na+ channel could be activated by a similar mechanism. This idea can be tested directly by observing tyrosine or tryptophan radicals when the channels are in the open state.
Lee
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Chemical Dynamics Corporation, Guilderland, NY 12084.
D004579:Electron Transport; D005609:Free Radicals; D015640:Ion Channel Gating; D015222:Sodium Channels / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D005609:Free Radicals; D015222:Sodium Channels; D014443:Tyrosine; D014364:Tryptophan