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An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects

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dc.contributor.author Smit, Jacoba E
dc.contributor.author Prinsloo, LC
dc.contributor.author Nel, JM
dc.date.accessioned 2012-08-20T09:47:30Z
dc.date.available 2012-08-20T09:47:30Z
dc.date.issued 2012-07
dc.identifier.citation Smit, JE, Prinsloo, LC and Nel, JM. An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects. SAIP 2012, University of Pretoria, 10-13 July 2012 en_US
dc.identifier.uri http://hdl.handle.net/10204/6056
dc.description SAIP 2012, University of Pretoria, 10-13 July 2012 en_US
dc.description.abstract Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in nature. The photosynthetic process is very much dependent on the aggregation state of the chlorophylls and secondary conformational structure of the apoproteins in the light-harvesting systems. The aim of this study was to test possible buffer influence on these in the light-harvesting complex (LHCII) of Photosystem II (PSII). LHCII was extracted from spinach leaves in a 20 mM Tricine buffer to stabilise the proteins, after which samples were diluted in 20 mM Tricine (pH 7.61) and 60 mM Tricine (pH 7.6) buffers respectively. Additionally, the 20 mM Tricine buffer was dialysed out of some of the LHCII stock samples directly into a 20 mM K2HPO4 / KH2PO4 buffer (pH 7.64) to prevent denaturing of the LHCII proteins. FTIR and absorbance spectra of samples were compared. Gaussian curve-fitting based on second order derivative resolution enhancement were performed on the Amide I region of all the FTIR spectra to reveal the overlapping component contributions of the chlorophylls and apoproteins in the light-harvesting complexes. FTIR results from the light-harvesting complexes in the Tricine buffers indicated a downward shift by about 25 cm-1 of the Amide I peak compared to the K2HPO4 / KH2PO4 buffer results. This leads to the assumption that the apoproteins has undergone a conformational shift from mostly a-helical to b-sheet structure. The curve-fitting method, however, predicted a smaller downward shift of between 3 and 7 cm-1 of the apoproteins, indicating a slight unfolding of the aproteins to a more unordered coil-structure, masked by the stronger Tricine peaks at around 1624 cm-1 in the Amide I region. Results also indicated that the chlorophylls associated with these apoproteins assumed a less aggregated state, confirmed as a slight blue shift in the absorbance spectra. The results were more pronounced in the higher concentrate Tricine buffer. en_US
dc.language.iso en en_US
dc.relation.ispartofseries Workflow;9003
dc.subject Light-harvesting complexes en_US
dc.subject FTIR en_US
dc.subject Chlorophyll en_US
dc.subject Photosynthesis en_US
dc.title An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects en_US
dc.type Conference Presentation en_US
dc.identifier.apacitation Smit, J. E., Prinsloo, L., & Nel, J. (2012). An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects. http://hdl.handle.net/10204/6056 en_ZA
dc.identifier.chicagocitation Smit, Jacoba E, LC Prinsloo, and JM Nel. "An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects." (2012): http://hdl.handle.net/10204/6056 en_ZA
dc.identifier.vancouvercitation Smit JE, Prinsloo L, Nel J, An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects; 2012. http://hdl.handle.net/10204/6056 . en_ZA
dc.identifier.ris TY - Conference Presentation AU - Smit, Jacoba E AU - Prinsloo, LC AU - Nel, JM AB - Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in nature. The photosynthetic process is very much dependent on the aggregation state of the chlorophylls and secondary conformational structure of the apoproteins in the light-harvesting systems. The aim of this study was to test possible buffer influence on these in the light-harvesting complex (LHCII) of Photosystem II (PSII). LHCII was extracted from spinach leaves in a 20 mM Tricine buffer to stabilise the proteins, after which samples were diluted in 20 mM Tricine (pH 7.61) and 60 mM Tricine (pH 7.6) buffers respectively. Additionally, the 20 mM Tricine buffer was dialysed out of some of the LHCII stock samples directly into a 20 mM K2HPO4 / KH2PO4 buffer (pH 7.64) to prevent denaturing of the LHCII proteins. FTIR and absorbance spectra of samples were compared. Gaussian curve-fitting based on second order derivative resolution enhancement were performed on the Amide I region of all the FTIR spectra to reveal the overlapping component contributions of the chlorophylls and apoproteins in the light-harvesting complexes. FTIR results from the light-harvesting complexes in the Tricine buffers indicated a downward shift by about 25 cm-1 of the Amide I peak compared to the K2HPO4 / KH2PO4 buffer results. This leads to the assumption that the apoproteins has undergone a conformational shift from mostly a-helical to b-sheet structure. The curve-fitting method, however, predicted a smaller downward shift of between 3 and 7 cm-1 of the apoproteins, indicating a slight unfolding of the aproteins to a more unordered coil-structure, masked by the stronger Tricine peaks at around 1624 cm-1 in the Amide I region. Results also indicated that the chlorophylls associated with these apoproteins assumed a less aggregated state, confirmed as a slight blue shift in the absorbance spectra. The results were more pronounced in the higher concentrate Tricine buffer. DA - 2012-07 DB - ResearchSpace DP - CSIR KW - Light-harvesting complexes KW - FTIR KW - Chlorophyll KW - Photosynthesis LK - https://researchspace.csir.co.za PY - 2012 T1 - An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects TI - An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects UR - http://hdl.handle.net/10204/6056 ER - en_ZA


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