{"95231":{"#nid":"95231","#data":{"type":"event","title":"(0619) Prof. Noam Agmon (Hebrew Univ Jerusalem)","body":[{"value":"\u003Cp\u003EProf. Noam Agmon, Hebrew University Jerusalem\n\u003C\/p\u003E\n\u003Cp\u003EProton wires and proton exit in the green fluorescent protein\n\u003C\/p\u003E\n\u003Cp\u003EThe Green Fluorescence Protein (GFP) from the jellyfish Aequorea Victoria has attracted much interest as a biological fluorescence marker and an example of excited-state proton transfer (ESPT) in nature. The proton was assumed to migrate irreversibly in the ES to Glu222. In collaboration with Dan Huppert (Tel-Aviv), we have studied the transient fluorescence of the wild-type (wt) protein over a wide range of time and temperature.  Unexpectedly, the decay of the acid form of wt-GFP is non-exponential, exhibiting two different power-laws. Below ca. 230 K, we observe a t\u003Csup\u003E-1\/2\u003C\/sup\u003E power-law decay, suggesting one-dimensional diffusion along a pre-formed \u0022proton-wire\u0022 within the protein.  Indeed, the x-ray structure reveals such a proton-wire, extending beyond Glu-222, on which the proton is apparently trapped at low T.   If this interpretation is correct, it provides a first demonstration of proton-wire dynamics in real time.\n\u003C\/p\u003E\n\u003Cp\u003EAbove 230 K, the time-resolved kinetics drop below the t\u003Csup\u003E-1\/2\u003C\/sup\u003E asymptotics, exhibiting a t\u003Csup\u003E-3\/2\u003C\/sup\u003E behavior near room-temperature.  We show that this phase is not due to three-dimensional diffusion as previously postulated. It stems from an added irreversible sink term to the one-dimensional diffusion equation, depicting irreversible proton exit to solution. The x-ray data reveals that a \u0022threonine switch\u0022 (Thr-203) apparently opens above 230 K, establishing a short exit route. The interpretation is corroborated by analysis of the kinetics of the S205V mutant, in which the proton-wire is eliminated, but not the threonine switch.  Accordingly, we see in this case slow, exponential proton exit controlled by the conformational change, but no power-laws attributable to diffusion along the proton-wire.\n\u003C\/p\u003E\n\u003Cp\u003EFor more information contact \u003Ca href=\u0022mailto:laren.tolbert@chemistry.gatech.edu\u0022\u003EDr. Laren Tolbert\u003C\/a\u003E (404-894-4093) or \u003Ca href=\u0022mailto:solntsev@chemistry.gatech.edu\u0022\u003EDr. Kyril Solntsev\u003C\/a\u003E (404-385-4078).\n\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"Prof. Noam Agmon, Hebrew University Jerusalem","format":"limited_html"}],"field_summary_sentence":[{"value":"Prof. Noam Agmon (Hebrew Univ Jerusalem)"}],"uid":"27275","created_gmt":"2006-04-18 00:00:00","changed_gmt":"2016-10-08 01:57:36","author":"Shirley Tomes","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2006-06-19T16:00:00-04:00","event_time_end":"2006-06-19T17:00:00-04:00","event_time_end_last":"2006-06-19T17:00:00-04:00","gmt_time_start":"2006-06-19 20:00:00","gmt_time_end":"2006-06-19 21:00:00","gmt_time_end_last":"2006-06-19 21:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"related_links":[{"url":"http:\/\/www.fh.huji.ac.il\/~agmon\/","title":"Prof. Noam Agmon, Hebrew University Jerusalem"}],"groups":[{"id":"85951","name":"School of Chemistry and Biochemistry"}],"categories":[],"keywords":[{"id":"89","name":"chemistry"},{"id":"5917","name":"organic electronics"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1789","name":"Conference\/Symposium"}],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EShirley Tomes\u003C\/strong\u003E\u003Cbr \/\u003EChemistry \u0026amp; Biochemistry\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=st81\u0022\u003EContact Shirley Tomes\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-0591\u003C\/strong\u003E","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}