Reaction Centers of Purple Bacteria with Modified Chromophores

Scheer, Hugo; Beese, D.; Steiner, Robert F.; Angerhofer, Alexander

doi:10.1007/978-1-4899-0815-5_12

Cited by 4 publications

(5 citation statements)

References 31 publications

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“…132-OH- BChl a, (3b), which is hydroxylated at C-132 and esterified with geranyl-geraniol instead of phytol at the propionic acid side chain. Exchange of the parent pigment, BChl agO (lb), has been established before [20], as has more recently the exchange pf BChl a with other esters (unpublished).…”

Section: Resultsmentioning

confidence: 97%

“…This and results of competition experiments (unpublished) indicate an affinity which increases in the order BChl a' (lc), BChl a (la,b) and 132-OH-BChl a (2). It should be noted, that 132-OHBChl a (3) is also present as a C-132-epimer mixture, but [20,21]. The function of the former has recently been shown to be an intermediate electron carrier [ 131, the latter is possibly involved in (triplet) energy transfer [26].…”

Section: Resultsmentioning

confidence: 99%

“…Exchange experiments were performed by the method of Scheer et al [20,21] using a 20-fold excess of exogenous pigments over the BChl a contained in the reaction centers. Excess pigments were removed from the incubation mixture by repeated chromatography on DEAEcellulose.…”

Section: Published By Elseviermentioning

confidence: 99%

“…A more general approach to modify the tetrapyrrolic pigments has been initiated by Loach et [20,21]. This method is currently explored to test the importance of the various functional groups in the tetrapyrrole pigment for binding and function.…”

Section: Introductionmentioning

confidence: 99%

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Modified reaction centers from Rhodobacter sphaeroides R26

Struck¹,

Scheer²

1990

FEBS Letters

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Incubation of photosynthetic reaction centers from Rhodobucter sphaeroides R26 with exogenous lY-OH-bacteriochlorophyll ar or aoo according to Scheer et al. (1987) results in the exchange of endogenous bacteriochlorophyll ar. The exchange amounts to 5 50% according to HPLC analysis, corresponding to a complete replacement of the 'monomeric' bacteriochlorophylls, Bu and Br, by exogenous pigment. The absorption spectra show small, but distinct changes in the Qx-region of the bacteriochlorophylls, and bleaching of the modified reaction centers is retained. The corresponding binding sites must be accessible from the exterior, and allow for the introduction of a polar residue at C-1P. This is supported by the observation of side reactions of the endogenous 'monomeric' bacteriochlorophylls within the reaction center pigments, e.g. epimerization and hydroxylation at C-l32.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Published By Elseviermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modified reaction centers from Rhodobacter sphaeroides R26

Struck¹,

Scheer²

1990

FEBS Letters

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“…Today there are several possibilities available to modify either the amino-acid [10][11][12][13][14][15][16] and/or the pigment composition [17][18][19][20]. Historically, however, treatment with borohydride was the first method by which reaction centers from Rb.…”

Section: Introductionmentioning

confidence: 99%

Modified bacterial reaction centers. 4. The borohydride treatment reinvestigated: comparison with selective exchange experiments at binding sites BA,B and HA,B

Struck¹,

Müller²,

Scheer³

1991

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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Pigments of borohydride-treated reaction centers of Rhodobacter sphaeroides R 26 and Rhodopseudomonas viridiswere analyzed by HPLC with polychromatie detection. In both species, pigment composition and contents were unchanged. Reaction centers from Rhodobacter sphaeroides R26 were prepared in which bacteriochlorophylls (B A B) and bacteriopheophytins (HA, n) were exchanged with their potential borohydride products reduced at C-3 t.[3-Hydroxyethyl]-BChl a exchanges selectively into the BA, B pockets, and 31-OH-BPh a to the HA, B pockets. Stable reaction centers are obtained in both cases. A comparison of the absorption and circular dichroism spectra of reaction centers after exchange with 31-OH pigments, and of borohydride-modified reaction centers, reveal distinct differences. It is concluded that during borohydride reduction none of the pigments is chemically modified or extracted from the reaction centers.

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