Hydrogen bonding of water to chlorophyll a and its derivatives as detected by 1H-NMR spectroscopy

https://doi.org/10.1016/0005-2728(93)90243-9Get rights and content

Abstract

Using 1H-NMR spectroscopy, evidence is presented for the hydrogen bonding of water to the C-131 keto carbonyl of chlorophyll a and some of its derivatives. This evidence is based on the observation of a low-field proton signal at approx. 11 ppm from samples prepared by dissolving the water adduct of each phorbin derivative in tetrahydrofuran-d8. When the temperature of the sample is elevated or lowered, the low-field signal becomes broader or narrower, respectively. After the addition of a small amount of 2H2O to the solution, the signal disappears in approx. 10 h at −40°C. Because the pyro derivatives lacking the 132-methoxycarbonyl group and the ‘prime derivatives’ possessing the 132(S) configuration as well as the Mg-free derivatives of these phorbins, also show a similar low-field proton signal, it is concluded that this signal arises from the 131−C=O … H2O hydrogen bond. The strength of this hydrogen bond is estimated to be approx. 8 kcal mol−1 (33.5 kJ mol−1). The difficulties encountered in the dehydration of chlorophyll preparations are interpreted in terms of this relatively strong hydrogen bond and the cebtral Mg … OH2 interaction of comparable strength. The importance of preserving chlorophyll preparations in their anhydrous and amorphous form is emphasized, because of the higher stability of these forms as compared to the photoactive chlorophyll-water adducts.

References (54)

  • J.J. Katz et al.
  • J.J. Katz et al.
  • T.M. Cotton et al.

    Biochim. Biophys. Acta

    (1974)
  • A.R. Holzwarth et al.

    J. Photochem. Photobiol. A: Chem.

    (1992)
  • Z.G. Fetisova et al.

    FEBS Lett.

    (1992)
  • D.E. Tronrud et al.

    J. Mol. Biol.

    (1986)
  • C.H. Chang et al.

    FEBS Lett.

    (1986)
  • F.K. Fong et al.

    Biochim. Biophys. Acta

    (1976)
  • K. Ballschmiter et al.

    Biochim. Biophys. Acta

    (1969)
  • J.J. Katz et al.
  • J.J. Katz et al.

    Ann. Rev. Biophys. Bioeng.

    (1978)
  • G.R. Seely
  • H. Scheer et al.
  • J.J. Katz et al.

    Bull. Magn. Reson.

    (1983)
  • J.J. Katz et al.

    Ann. N.Y. Acad. Sci.

    (1973)
  • G.L. Closs et al.

    J. Am. Chem. Soc.

    (1963)
  • J.J. Katz et al.

    J. Am. Chem. Soc.

    (1963)
  • K. Ballschmiter et al.

    J. Am. Chem. Soc.

    (1969)
  • T.M. Cotton et al.

    Photochem. Photobiol.

    (1978)
  • L.L. Shipman et al.
  • H.-C. Chow et al.

    J. Am. Chem. Soc.

    (1975)
  • R. Serlin et al.

    J. Am. Chem. Soc.

    (1975)
  • K.M. Smith et al.

    J. Am. Chem. Soc.

    (1983)
  • M. Mimuro et al.

    J. Phys. Chem.

    (1989)
  • T.P. Causgrove et al.

    Photosynth. Res.

    (1990)
  • J.M. Olson et al.

    Photosynth. Res.

    (1990)
  • K. Uehara et al.

    Photosynth. Res.

    (1992)
  • Cited by (12)

    • Understanding chlorophylls: Central magnesium ion and phytyl as structural determinants

      2008, Biochimica et Biophysica Acta - Bioenergetics
      Citation Excerpt :

      However, in the absence of central Mg the QX transition shows its “inherent” weak sensitivity to solvent polarity as inferred from the plots drawn for the free bases, provided the effects of H-bonding are excluded. The sensitivity of the QY transition of BChl a to H-bond donors stems from the presence of the C-32 and C-131 carbonyls which may act as acceptors of hydrogen bonds [9,46,55,56]. However, aliphatic alcohols are too weak as H-bond donors to (B)Chls [40,54] to cause significant shifts in the energy of the QY transition in BChl a and BChlide a, observed in the present study.

    • Interaction of photosynthetic pigments with various organic solvents 2. Application of magnetic circular dichroism to bacteriochlorophyll a and light-harvesting complex 1

      2000, Biochimica et Biophysica Acta - Bioenergetics
      Citation Excerpt :

      The pigments are functioning in the light-capture and energy-transducing systems and usually are held in proteins, such as, antenna complexes of purple bacteria and reaction centers in green plants and bacteria. It is crucial to understand the nature of the pigments in order to elucidate the mechanism of photosynthesis, and consequently, Chl a and BChl a molecules have been profoundly investigated with various spectroscopic methods: absorption [3–9], infrared and resonance Raman [10–17], X-ray diffraction [1], and nuclear magnetic resonance [18–24]. ( B)Chl a contains a Mg atom in the center of macrocycle, which is coordinated by four pyrrole nitrogens.

    • Photosynthesis in Nature: A New Look

      2013, Environmental Science and Engineering
    • Photosynthesis in nature: A new look

      2013, Environmental Science and Engineering (Subseries: Environmental Science)
    View all citing articles on Scopus
    View full text