Reaction centers of Rhodobacter sphaeroides R-26 with selective replacement of bacteriopheophytin by pheophytin a

Modification of pigment composition in the isolated reaction center of photosystem II

“…In bacterial RC it is also possible to exchange the native bacteriopheophytin (BPhe) with a variety of other (B)Phes [40], in one case already at room temperature [38]. Attempts to repeat this with PSII‐RC have failed: exchange with pheophytins (BPhe a , [3‐acetyl]‐pheophytin a ) was not successful.…”

“…use of high pressure [16]or pH‐dependent dissociation and reassociation [37]. With bacterial RC, temperatures around 40°C were needed for exchange (although H B exchange was reported at ambient temperature [38]). For PSII‐RC 30°C was sufficient to achieve modification.…”

Nuclear wavepacket motion producing a reversible charge separation in bacterial reaction centers

“…The participation of bacteriochlorophyll monomer B A (active pigment branch A) in electron transfer (ET) was suggested by ps measurements in 1978 [3] and since that, the mechanism of an involvement of B A in ET was studied in many further works [4–14]. Recent measurements in pheophytin a ‐reconstituted RCs [6–8,12–14] and in the β‐mutant [10] have shown that the free energy level of the P + B A − state in these modified RCs is close to or even below that of P* by 350–550 cm −1 [15,16]. The time constant for ET from P* to B A is about 1.6 ps at 5 K in pheophytin‐modified RCs [14], which is similar to that for native RCs.…”

Reaction centers of photosystem II with a chemically‐modified pigment composition: exchange of pheophytins with 131‐deoxo‐131‐hydroxy‐pheophytin a

“…Of particular interest is the application to the PS II RC of a pigment exchange technique based on replacement of the native chromophores with exogenous pigments having different structural, spectral and redox characteristics [10–12]. Recently, it has been shown [9] that one of the six Chl molecules present in PS II RC could be replaced by (3‐acetyl)‐Chl or Zn‐Chl using the chemical exchange procedure following that developed with the bacterial RCs [10–12]. The first attempts to exchange Pheo against pheophytin derivatives (bacteriopheophytin a , (3‐acetyl)‐Pheo) were, however, not successful [9].…”