Wavelength shifts correlation between near infrared and ultraviolet regions of the LHII bacteriochlorophyll spectrum from Ectothiorhodospira sp.
Bacteriochlorophyll a has a maximum at 258 nm previously related to the ring E ester system interacting with the pi-system of the macrocycle. In this work, we compared the effect of lauryldimethylamine-N-oxide (LDAO) and alkaline pH on both the near infrared and the ultraviolet region of the LHII spectrum from Ectothiorhodospira sp. While LDAO induces only a shift of the 850 nm band arising from the Qy transition of the bacteriochlorophyll a, alkaline pH also causes a concomitant and reversible 10-nm shift from 258 to 248 nm. Both shifts have similar apparent pKs (12.3 and 12.6, respectively). Interestingly, the presence of NaCl reduces these pKs values to 11.4 and 11.7.
Buche
A
A
Estación Experimental de Aula Dei (CSIC), Zaragoza, Spain. abuche@eead.csic.es
D001429:Bacteriochlorophylls / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004123:Dimethylamines; D020587:Ectothiorhodospira / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D013053:Spectrophotometry; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
D001429:Bacteriochlorophylls; D004123:Dimethylamines; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; C014518:dodecyldimethylamine oxide