Accession Number : AD1033050


Title :   How do light harvesting proteins support long lived quantum coherences


Descriptive Note : Technical Report,31 Aug 2015,30 Aug 2016


Corporate Author : UNIVERSITY OF NEW SOUTH WALES KENSINGTON Austria


Personal Author(s) : Curmi, Paul


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/1033050.pdf


Report Date : 31 Jan 2017


Pagination or Media Count : 11


Abstract : Cryptophyte algae use light harvesting proteins to facilitate photosynthesis under low light conditions. Two-dimensional electronic spectroscopy (2DES) of these proteins indicates that they utilize non-trivial quantum coherence phenomena in their function. Our aim is to probe the structural origin of these quantum effects. We have previously discovered that these algae can produce two structurally distinct light harvesting proteins: a closed form that supports quantum coherence and an open form that does not. To determine the structural basis for these two forms, our aim is to generate hybrid proteins via synthetic biology approaches. We have shown that we can fully unfold and separate the alpha and beta subunits that make up the light harvesting proteins. We can then recombine these and refold the proteins. The refolded wildtype proteins show the same 2DES are the natural proteins. We have then created hybrid proteins taking either alpha or beta subunits from open and closed forms and recombining them with the complementary subunit from the opposite form. These hybrid proteins refold as determined by both optical and far UV circular dichroism spectroscopy. The hybrid proteins differ from wild type proteins in that they elute from size exclusion chromatography as if they are heterodimers rather than the wild type heterotetramers. We have succeeded in crystallizing hybrid proteins for high resolution structure determination. The hybrid proteins are soluble and stable and should be amenable to 2DES for evaluation of quantum coherences.


Descriptors :   photosynthesis , proteins , crystal structure , quantum efficiency


Subject Categories : Biology
      Quantum Theory and Relativity


Distribution Statement : APPROVED FOR PUBLIC RELEASE