Document Detail


Comparative Photoactivity and Stability of Isolated Cyanobacterial Monomeric and Trimeric Photosystem I.
MedLine Citation:
PMID:  24547776     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Photoactivity of native trimeric, and non-native monomeric Photosystem I (PSI) extracted from Thermosynechococcus elongatus is compared in a photoelectrochemical system. The PSI monomer is isolated by disassembling a purified PSI trimer using a freeze-thaw technique in presence of the short-chain surfactant, octylthioglucoside. Photoactive electrodes are constructed with PSI, functioning as both light absorber and charge-separator, embedded within a conductive polymer film. Despite structural differences between PSI trimers and monomers, electrodes cast with equal chlorophyll-a concentration generate similar photoactivities. Photoaction spectra show that all photocurrent derived from electrodes of PSI and conductive polymer originates solely from PSI with no photocurrent caused by redox mediators in the conductive polymer film. Longevity studies show that the two forms of PSI photodegrade at the same rate; 40 % per hour while exposed to equal intensities of 676 nm light. Direct photo-oxidation measurements indicate that PSI's monomeric form has fewer light harvesting antennae than trimer, and also shows energy sharing between monomeric subunits in the trimer. The structure of PSI is also found to impact cell performance when applying light at incident powers above 1.5 mW/cm2 due to the reduced optical cross-section in the monomer; causing saturation at lower light intensities than the trimer.
Authors:
David R Baker; Amy K Manocchi; Melissa L Lamicq; Meng Li; Khoa Nguyen; James Jeffery Sumner; Barry D Bruce; Cynthia A Lundgren
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-2-18
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  -     ISSN:  1520-5207     ISO Abbreviation:  J Phys Chem B     Publication Date:  2014 Feb 
Date Detail:
Created Date:  2014-2-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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