Tham khảo tài liệu 'advances in photosynthesis fundamental aspects part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 142 Advances in Photosynthesis - Fundamental Aspects flavoprotein semiquinones reaction 3 in Scheme 2 followed by the reduction of a second Fldox molecule by the FNRsq produced in the first step reaction 4 in Scheme 2 Casaus et al. 2002 Medina et al. 1998 Nogués et al. 2005 . The spectral evolutions acquired using the PDA detector confirm such mechanism and allowed to improve the assignment of intermediates and the major contribution of apparent rate constants to particular steps of the process. Fld form Eox sq Esq hq mV mV AEox sq AEox WT mV - AEsq hq AEsq hqWT mV FNRoxiFldox pM WTa -256 -445 --- --- E16K E61Ka -301 -390 -45 55 46 E16K E61K D126K D150K -297 -391 -41 54 --- FNR form WTb -325 -338 --- --- 3c E301A -284b -358b 41 -20 4c Table 2. Midpoint reduction potentials for the different Anabaena Fld and FNR forms. Data obtained in 50 mM Tris HCl at pH and 25 C for Flda and at 10 C for FNRb. aData from Goni et al. 2009 . bData from Faro et al. 2002b . cData from Medina et al. 1998 . kA - B kB - C f A 2 f A FNRhq Fldox FNRhq Fldox -------------- FNRsq Fldsq 3 FNRsq Fldox FNRsq Fldox ------ FNRox Fldsq 4 kB - - C kC- - D Scheme 2. Reaction pathways describing the processes observed for the reaction of the FNRhq variants with the Fldox variants. Thus for the process with the E16K E61K Fld variant the step corresponding to complex formation-reorganisation was erroneously related with an ET step in a previous study. At the lowest ionic strength assayed our data indicate that E16K E61K Fldox and particularly E16K E61K D126 D150K Fldox are still able to accept electrons from FNRox with apparent rates that only decreased by 2-fold and with final production of FNRox occurring in higher degree that in the WT system Table 1 Fig. 8 and 10 . Their slightly more negative Eox sq values Table 2 makes them poorer electron acceptors from FNRhq than WT Fld and might explain the small differences in rates Goni et al. 2009 . Additionally E301A FNRhq is also able to pass .
