EPR study of trapped tyrosine Z+ in Ca-depleted photosystem II

Kodera, Yoshio; Hara, Hideyuki; Astashkin, Andrei V.; Kawamori, Asako; Ono, Tetsuya

doi:10.1016/0005-2728(95)00108-3

Cited by 56 publications

(38 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The values obtained by a "2+1" ESE method are most accurate among the values derived by other EPR methods, because other methods cannot detect selectively the magnetic dipole interaction between radicals in the form of oscillation frequency [33,34]. With this method, the distance between Yp and Chlz was estimated to be 29.4 ± 0.5 A [30] and the angular dependence suggests that the angle between the distance vector from Y p to Chl, R, and the membrane normal, n, is 50.0 ± 5° in this work.…”

Section: Discussionmentioning

confidence: 80%

“…For pairwise distributed spins, the primary ESE signal intensity in the "2+I" method depends on the time position of the second mw pulse, r', as described by the following formula [21][22][23][24][25]28]:…”

Section: Theorymentioning

confidence: 99%

“…By applying these techniques, we have been able to improve the accuracy in estimation of the distances and in acquisition of the angular information between the redox-active components in PS II significantly [23][24][25]28]. The distances from Y D to YZ and to the Mn cluster in WOC have been measured to be about 29 and 27 A, respectively [23][24][25]. The distance between Y p and the species giving so-called S3 signal in Ca 21_ depleted PS II was found to be about 30 A [25].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Three-dimensional structure of electron transfer components in photosystem II: “2 + 1” ESE of chlorophyll Z and tyrosine D

Tonaka

Kawamori

Hara³

et al. 2000

Appl. Magn. Reson.

View full text Add to dashboard Cite

A "2+1" electron spin echo method has been applied to measure the orientation of the distance vector R from the redox-active tyrosine residue Y D to chlorophyll Z Chl in a membraneoriented Mn-depleted preparation of photosystem II. The angle between R and the normal n to the photosystem II membranes was determined to be 50.0 ± 5 0 with the value of the dipolar interaction parameter Do = 2.0 MHz, the corresponding distance of 29.4 ± 0.5 A, determined in a nonoriented PS II sample.

show abstract

Section: Discussionmentioning

confidence: 80%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional structure of electron transfer components in photosystem II: “2 + 1” ESE of chlorophyll Z and tyrosine D

Tonaka

Kawamori

Hara³

et al. 2000

Appl. Magn. Reson.

View full text Add to dashboard Cite

show abstract

“…The new estimates range now between 8.6 and 11.5 Å (24). Moreover, the other paramagnet may not be Mn but an organic radical (component X) (9,(30)(31)(32). The proton that appears in the medium upon formation of Y Z ox in oxygen-eVolVing PSII does not originate from the tyrosine itself but from peripheral amino acid groups which electrostatically interact with the charge residing transiently on Y Z ox and thereafter on the Mn cluster ((33)…”

mentioning

confidence: 99%

Tyrosine-Z in Oxygen-Evolving Photosystem II: A Hydrogen-Bonded Tyrosinate

1998

View full text Add to dashboard Cite

In oxygen-evolving photosystem II (PSII), a tyrosine residue, D1Tyr161 (Y Z ), serves as the intermediate electron carrier between the catalytic Mn cluster and the photochemically active chlorophyll moiety P 680 . A more direct catalytic role of Y Z , as a hydrogen abstractor from bound water, has been postulated. That Y Z ox appears as a neutral (i.e. deprotonated) radical, Y Z • , in EPR studies is compatible with this notion. Data based on electrochromic absorption transients, however, are conflicting because they indicate that the phenolic proton remains on or near to Y Z ox . In Mn-depleted PSII the electron transfer between Y Z and P 680 + can be almost as fast as in oxygen-evolving material, however, only at alkaline pH. With an apparent pK of about 7 the fast reaction is suppressed and converted into an about 100-fold slower one which dominates at acid pH. In the present work we investigated the optical difference spectra attributable to the transition Y Z f Y Z ox as function of the pH. We scanned the UV and VIS range and used Mn-depleted PSII core particles and also oxygen-evolving ones. Comparing these spectra with published in vitro and in vivo spectra of phenolic compounds, we arrived at the following conclusions: In oxygen-evolving PSII Y Z resembles a hydrogen-bonded tyrosinate, Y Z (-) ‚‚‚H (+) ‚B. The phenolic proton is shifted toward a base B already in the reduced state and even more so in the oxidized state. The retention of the phenolic proton in a hydrogen-bonded network gives rise to a positive net charge in the immediate vicinity of the neutral radical Y Z • . It may be favorable both for the very rapid reduction by Y Z of P 680 + and for electron (not hydrogen) abstraction by Y Z • from the Mn-water cluster.Photosystem II (PSII) 1 produces molecular oxygen from water. It is located in photosynthetic membranes of plants and cyanobacteria. The inner core of PSII is a heterodimer of the D1D2 subunits which show homology with the L and M subunits of the purple bacterial RC (1). The primary electron donor of PSII, P 680 , is located close to the lumenal side of the membrane. The absorption of a quantum of light drives the charge separation between P 680 and the quinone acceptor at the stromal side (2). The very high redox potential of P 680 + drives water oxidation. It is a four-stepped process with at least four increasingly oxidized, metastable states S 0 to S 3 , plus a transient state S 4 that decays in milliseconds into S 0 under release of O 2 . P 680 + is reduced (in nanoseconds) by a redox-active tyrosine residue, Y Z (D1Tyr161 (3, 4)). Y Z ox is, in turn, reduced in microseconds by the oxygenevolving complex (OEC). The structure and exact location of the OEC is still ill-defined. It is formed by four manganese atoms (5, 6), possibly another redox cofactor, X (7-9), plus at least one Cl -ion (10) and one Ca 2+ (11, 12) ion. These cofactors serve various functions during water oxidation: The Mn cluster stores at least two of the oxidizing equivalents (namely on transitions S ...

show abstract

“…Ca-depletion followed the low-pH protocol of Ono and Inoue: 32 30 mM NaCl, pH 7.5) returned the mixture to pH 6.5. 68,69 After stirring for 2 min, the membranes were collected by centrifugation (10 min at 40000 g).…”

Section: Sr 2+ -Reactivated Ps II Sample Preparationmentioning

confidence: 99%

X-ray absorption spectroscopy on the calcium cofactor to the manganese cluster in photosynthetic oxygen evolution

Cinco¹

1999

View full text Add to dashboard Cite

PS II). To further test and verify whetherCa is close to the Mn cluster, we substituted strontium for Ca and probed from the Sr point of view for any nearby Mn. The extended X-ray absorption fine structure (EXAFS) of Sr-reactivated PS II indicates major differences between the intact and NH 2 OH-treated samples. In intact samples, the Fourier transform of the Sr EXAFS shows a Fourier peak that is missing in inactive samples. This peak II is best simulated by two Mn neighbors at a distance of 3.5 Å, confirming the proximity of Ca (Sr) cofactor to the Mn cluster. In addition, polarized Sr EXAFS on oriented Sr-reactivated samples shows this peak II is dichroic: large magnitude at 10° (angle between the PS II membrane normal and the x-ray electric field vector) and small at 80°. Analysis of the dichroism yields the relative angle between the Sr-Mn vector and membrane normal (23° ± 4°), and the isotropic coordination number for these layered samples.ii X-ray absorption spectroscopy has also been employed to assess the degree of similarity between the manganese cluster in PS II and a family of synthetic manganese complexes containing the distorted cubane [Mn 4 O 3 X] core (X = benzoate, acetate, methoxide, hydroxide, azide, fluoride, chloride or bromide). In addition, Mn 4 O 3 Cl complexes containing three or six terminal Cl ligands at three of the Mn were included in this study. The EXAFS method detects the small changes in the core structures as X is varied in this series, and serves to exclude these distorted cubanes of C 3v symmetry as a topological model for the Mn catalytic cluster.The sulfur K-edge x-ray absorption near-edge structure (XANES) spectra for the amino acids cysteine, methionine, their corresponding oxidized forms cystine and methionine sulfoxide, and glutathione show distinct differences between the thiol and disulfide forms. Sulfur XANES is also used to detect changes (within 5%) of the thiol-to-disulfide ratio in whole human blood, plasma, and erythrocytes.iii To my parents, and to my brothers Raoul and Dannyi v

show abstract

EPR study of trapped tyrosine Z+ in Ca-depleted photosystem II

Cited by 56 publications

References 33 publications

Three-dimensional structure of electron transfer components in photosystem II: “2 + 1” ESE of chlorophyll Z and tyrosine D

Three-dimensional structure of electron transfer components in photosystem II: “2 + 1” ESE of chlorophyll Z and tyrosine D

Tyrosine-Z in Oxygen-Evolving Photosystem II: A Hydrogen-Bonded Tyrosinate

X-ray absorption spectroscopy on the calcium cofactor to the manganese cluster in photosynthetic oxygen evolution

Contact Info

Product

Resources

About