Spectral signatures of five hydroxymethyl chlorophyll a derivatives chemically derived from chlorophyll b or chlorophyll f

Artur Sawicki, Robert D. Willows, Min Chen*

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Chlorophylls (Chls) are pigments involved in light capture and light reactions in photosynthesis. Chl a, Chl b, Chl d, and Chl f are characterized by unique absorbance maxima in the blue (Soret) and red (Qy) regions with Chl b, Chl d, and Chl f each possessing a single formyl group at a unique position. Relative to Chl a the Qy absorbance maximum of Chl b is blue-shifted while Chl d and Chl f are red-shifted with the shifts attributable to the relative positions of the formyl substitutions. Reduction of a formyl group of Chl b to form 7-hydroxymethyl Chl a, or oxidation of the vinyl group of Chl a into a formyl group to form Chl d was achieved using sodium borohydride (NaBH4) or β-mercaptoethanol (BME/O2), respectively. During the consecutive reactions of Chl b and Chl f using a three-step procedure (1. NaBH4, 2. BME/O2, and 3. NaBH4) two new 7-hydroxymethyl Chl a species were prepared possessing the 3-formyl or 3-hydroxymethyl groups and three new 2-hydroxymethyl Chl a species possessing the 3-vinyl, 3-formyl, or 3-hydroxymethyl groups, respectively. Identification of the spectral properties of 2-hydroxymethyl Chl a may be biologically significant for deducing the latter stages of Chl f biosynthesis if the mechanism parallels Chl b biosynthesis. The spectral features and chromatographic properties of these modified Chls are important for identifying potential intermediates in the biosynthesis of Chls such as Chl f and Chl d and for identification of any new Chls in nature.

Original languageEnglish
Pages (from-to)115-127
Number of pages13
JournalPhotosynthesis Research
Volume140
Issue number1
DOIs
Publication statusPublished - Apr 2019

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Keywords

  • Chlorophyll
  • Chlorophyll derivative
  • Chlorophyll f
  • Vinyl oxidation
  • Hydroxymethyl
  • Formyl reduction

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