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Identifier 000369250
Title Ο ρόλος της σπερμίνης στο κέντρο αντίδρασης του φωτοσυστήματος ΙΙ
Alternative Title The role of spermine in the reaction center of photosystem II
Author Ναούμ, Ιωάννης
Thesis advisor Κοτζαμπάσης, Κυριάκος
Reviewer Γανωτάκης, Δημήτριος
Πυρίντσος, Στέργιος
Abstract Polyamines include a large number of organic molecules with more than one amino groups, and are found in all organisms. The most important are the diamines agmatine and putrescine, the triamine spermidine and the tetramine spermine. Studies have shown that Put, Spd and Spm are present in intact chloroplasts, particularly in thylakoids membranes, in PS II membranes and in the light harvesting complex, LHCII (Kotzabasis et al., 1993). Additionally, only spermine was detected in photochemically active PS II reaction centers and in the PS II core (Kotzabasis et al., 1993). Through this master thesis was made an attempt to identify and understand the role of spermine in the reaction center of photosystem II, in vitro, after isolation of PSII enriched membranes. At low concentrations (<100mM), exogenous spermine increased chlorophyll fluorescence. The time needed to reach the maximal fluorescence intensity (Fmax) is increased in the presence of spermine, suggesting that , somehow, spermine keeps QA oxidized, probably acting as ionophore. In contrast, high concentrations of spermine, more than 100mM, induced release of the three extrinsic polypeptides of photosystem II, with apparent molecular weights of 17, 23 and 33kDa. The loss of the tree extrinsic polypeptides has resulted in reduction of the maximal fluorescence induction and inhibition of oxygen evolution. Spermine, like other primary amines, is purely competitive with Cl-, as was found in steady state inhibition studies of photosystem II. Finally, EPR spectroscopy revealed the presence of spermine in the complex of Mn. Moreover, exogenously supplied spermine prevented the transition to state S3, probably due to binding of polyamine in S2 state.
Language Greek
Subject EPR specroscopy
EPR φασματοσκοπία
Issue date 2011-11-18
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
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