The environment of the four nitrogen atoms of bacteriochlorophyll a in solutions as revealed by 15N NMR spectroscopy

Limantara, Leenawaty; Kurimoto, Yoshitaka; Furukawa, Kenji; Shimamura, Toshio; Utsumi, Hiroaki; Katheder, Ingrid; Scheer, Hugo; Koyama, Yasushi

doi:10.1016/0009-2614(95)00183-5

Cited by 8 publications

(11 citation statements)

References 10 publications

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“…All of the proposed assignments indicated in the following are based on available chemical shift data and comparison with previously characterized systems, and some are confirmed by additional experiments described below. The peaks at 163, 173, 232, and 236 ppm strongly resemble reported chemical shifts obtained with cross-polarization MAS from a solid sample of bacteriochlorophyll 20 as well as those from bacteriochlorophyll in solution . We tentatively assign these peaks to the nitrogen nuclei on one of the bacteriochlorophylls that form the special pair, most likely the one that carries the larger electron density, although additional bacteriochlorophyll species in the reaction center could also contribute.…”

Section: Resultssupporting

confidence: 70%

“…It is highly improbable, assuming diamagnetic complexes, that other functional groups would be so perturbed as to appear in these ranges, given that typical environmental perturbations are maximally of the order of 10 ppm. For example, the dependence of 15 N chemical shifts in bacteriochlorophyll on the polarizability of the solvent showed a maximum deviation of only about 7.5 ppm . This modest dependence of shift on environmental factors may also preclude resolution of the two bacteriochlorophylls on the special pair, regardless of the asymmetry of the environment that surrounds them.…”

Section: Resultsmentioning

confidence: 99%

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Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the ¹⁵N SSNMR Spectra^,

Zysmilich

McDermott

1996

J. Am. Chem. Soc.

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We report proposed chemical assignments of polarized nitrogen NMR signals from photosynthetic reaction centers of Rb. sphaeroides. These signals, which we previously described, are observed with solid state NMR methods in samples of Q-blocked reaction centers that are enriched in 15N. The CIDNP is excited by CW illumination with a Xenon arc lamp; we presume that they result from a radical pair mechanism (RPM) involving mixing of the electronic triplet and singlet spin states of P•+I•-. In this work selective labeling and comparison with chemical shifts of model compounds were used to assign the signals and were also used to distinguish directly and indirectly polarized signals. Signals at isotropic shifts of 163, 173, 232, and 236 ppm (relative to 1 M 15NH4Cl in 2 N HCl) were assigned as arising from the tetrapyrrole nitrogens of the special pair P865, and all appear to be directly polarized from the RPM. An additional small peak at 167 ppm appear to be another bacteriochlorophyll species, either the monomeric “B” or the “other half” of P865. Signals at 105, 113, and 276 ppm arise from the tetrapyrrole nitrogens of the bacteriopheophytin acceptor (“I”), and some of these signals (particularly the nitrogens in rings II and IV) seem to be directly polarized, while others are polarized by homonuclear spin diffusion involving a neighboring directly polarized nitrogen. Signals at 147 and 201 ppm arise from the δ and ε nitrogens of histidine, presumably from the ligand of P865, and are indirectly polarized. The intensities of the bacteriopheophytin signals are sensitive to the lifetime of 3P, consistent with a RPM mechanism in which 3P acts as the nuclear relaxant for I; this was concluded from comparisons of samples in which the acceptor QA was prereduced and samples in which is was chemically extracted, which are known from previous work to differ strongly in the lifetime of 3P. Many of the signals have chemical shift values that closely correspond to related model compounds, but moderate deviations (ca. 10 ppm) are seen for a few including the histidine resonances.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the ¹⁵N SSNMR Spectra^,

Zysmilich

McDermott

1996

J. Am. Chem. Soc.

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“…[12] The 1 H NMR spectrum of BChl a was reported in Refs [13][14][15] and the observed chemical shifts were in agreement with the values reported for acetone but differed markedly from those recorded in pyridine-D 5 solution. [7] The 15 N NMR data for BChl a in solution were reported in Refs [16,17]. Thus controversial assignments, misassignments and re-assignments have been reported for these bacterial pigments either using natural abundance molecules or applying selective stable-isotope labelling.…”

Section: Introductionmentioning

confidence: 98%

“…correlation (HMBC) spectra in acetone-d 6 solution or by measuring Correlation by long-range coupling (COLOC) spectra. [16] The 1D 15 N CP MAS NMR spectra of pigments were recorded using the TPPM technique. The assignment of N-I and N-III in [U-13 C, 15 N] BPheo a was confirmed from the 13 C-15 N correlation spectrum.…”

mentioning

confidence: 99%

Characterisation of uniformly ¹³C, ¹⁵N labelled bacteriochlorophyll a and bacteriopheophytin a in solution and in solid state: complete assignment of the ¹³C, ¹H and ¹⁵N chemical shifts

Egorova‐Zachernyuk

Rossum

Erkelens

et al. 2008

Magnetic Reson in Chemistry

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In this investigation we report a complete assignment of (13)C, (1)H and (15)N solution and solid state chemical shifts of two bacterial photosynthetic pigments, bacteriochlorophyll (BChl) a and bacteriopheophytin (BPheo) a. Uniform stable-isotope labelling strategies were developed and applied to biosynthetic preparation of photosynthetic pigments, namely uniformly (13)C, (15)N labelled BChl a and BPheo a. Uniform stable-isotope labelling with (13)C, (15)N allowed performing the assignment of the (13)C, (15)N and (1)H resonances. The photosynthetic pigments were isolated from the biomass of photosynthetic bacteria Rhodopseudomonas palustris 17001 grown in uniformly (13)C (99%) and (15)N (98%) enriched medium. Both pigments were characterised by NMR in solution (acetone-d(6)) and by MAS NMR in solid state and their NMR resonances were recorded and assigned through standard liquid 2D (13)C-(13)C COSY, (1)H-(13)C HMQC, (1)H-(15)N HMBC and solid 2D (13)C-(13)C RFDR, (1)H-(13)C FSLG HETCOR and (1)H-(15)N HETCOR correlation techniques at 600 MHz and 750 MHz. The characterisation of pigments is of interest from biochemical to pharmaceutical industries, photosynthesis and food research.

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“…This paper presents a study of the 13 C and 15 N chemical shifts in methyl bacteriopheophorbide a (MBPheo-a) and bacteriochlorophyll a (BChl-a), two important chlorophylls that have been previously studied by liquid NMR. , Several molecular structures are available for MBPheo-a from X-ray studies, − as well as an optimized structure obtained from DFT calculations including the crystal lattice . For BChl-a, to the author's knowledge, there are no high-resolution X-ray structures available; therefore a full optimization of its molecular structure was required to calculate the chemical shifts in this compound.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Calculations of the Structure and the ¹⁵N and ¹³C Chemical Shifts of Methyl Bacteriopheophorbide a and Bacteriochlorophyll a

Facelli

1998

J. Phys. Chem. B

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Ab initio (DFT) chemical shifts calculations and geometry optimizations were performed in methyl bacteriopheophorbide a (MBPheo-a) using the D95 and D95** basis sets and in bacteriochlorophyll a (BChl-a) using the LanL2DZ basis set. The results show that it is possible to calculate chemical shifts in large systems, such as MBPheo-a and BChl-a, and that the calculated chemical shifts are quite sensitive to the geometries used in their calculation. Calculations of the chemical shifts using molecular geometries in which at least the positions of the protons have been optimized produce results in much better agreement with the experimental values than those using the X-ray experimental structure. The results for 13C shifts are of such quality that they can be used to verify the assignments of NMR resonances separated by more than 5 ppm. The calculations presented here strongly suggest that several assignments of the 13C resonances of the pyrrolic ring carbons in MBPheo-a and BChl-a should be revised.

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The environment of the four nitrogen atoms of bacteriochlorophyll a in solutions as revealed by 15N NMR spectroscopy

Cited by 8 publications

References 10 publications

Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the ¹⁵N SSNMR Spectra^,

Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the ¹⁵N SSNMR Spectra^,

Characterisation of uniformly ¹³C, ¹⁵N labelled bacteriochlorophyll a and bacteriopheophytin a in solution and in solid state: complete assignment of the ¹³C, ¹H and ¹⁵N chemical shifts

Density Functional Theory Calculations of the Structure and the ¹⁵N and ¹³C Chemical Shifts of Methyl Bacteriopheophorbide a and Bacteriochlorophyll a

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The environment of the four nitrogen atoms of bacteriochlorophyll a in solutions as revealed by 15N NMR spectroscopy

Cited by 8 publications

References 10 publications

Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the 15N SSNMR Spectra,

Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the 15N SSNMR Spectra,

Characterisation of uniformly 13C, 15N labelled bacteriochlorophyll a and bacteriopheophytin a in solution and in solid state: complete assignment of the 13C, 1H and 15N chemical shifts

Density Functional Theory Calculations of the Structure and the 15N and 13C Chemical Shifts of Methyl Bacteriopheophorbide a and Bacteriochlorophyll a

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Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the ¹⁵N SSNMR Spectra^,

Photochemically Induced Nuclear Spin Polarization in Bacterial Photosynthetic Reaction Centers: Assignments of the ¹⁵N SSNMR Spectra^,

Characterisation of uniformly ¹³C, ¹⁵N labelled bacteriochlorophyll a and bacteriopheophytin a in solution and in solid state: complete assignment of the ¹³C, ¹H and ¹⁵N chemical shifts

Density Functional Theory Calculations of the Structure and the ¹⁵N and ¹³C Chemical Shifts of Methyl Bacteriopheophorbide a and Bacteriochlorophyll a