Conversion of chlorophyll b to chlorophyll a via 7-hydroxymethyl chlorophyll

J Biol Chem. 1996 Jan 19;271(3):1475-9. doi: 10.1074/jbc.271.3.1475.


Chlorophyll b is synthesized from chlorophyll a by the oxidation of the methyl group on the ring B of the tetrapyrrole ring to the formyl group. Previously, we reported that chlorophyllide b could be converted to chlorophyll a in isolated cucumber etioplasts indicating the conversion of chlorophyll b to chlorophyll a. To identify the intermediate molecule, we used barley etioplasts instead of cucumber. Chlorophyll a and an additional pigment were found after incubation of chlorophyllide b with isolated barley etioplasts. The pigment has the same retention time and absorption spectrum as 7-hydroxymethyl chlorophyll, which has the hydroxymethyl group on ring B instead of the formyl group of chlorophyll b. Authentic 7-hydroxymethyl chlorophyll was prepared by reduction of chlorophyll b by NaBH4. Chlorophyll a accumulated during the incubation of 7-hydroxymethyl chlorophyllide with etioplasts. These findings indicate that chlorophyll b is converted to chlorophyll a via 7-hydroxymethyl chlorophyll. Chlorophyll b and 7-hydroxymethyl chlorophyll accumulated within a short period of incubation of chlorophyllide b with etioplasts. However, chlorophyll a accumulated with a concomitant decrease of chlorophyll b and 7-hydroxymethyl chlorophyll. These observations also suggest that chlorophyll b is converted to 7-hydroxymethyl chlorophyll and then to chlorophyll a. Both steps required ATP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon Radioisotopes
  • Chlorophyll A
  • Chlorophyll* / chemistry*
  • Chlorophyll* / isolation & purification
  • Chlorophyll* / metabolism
  • Chromatography, High Pressure Liquid
  • Hordeum
  • Kinetics
  • Pigments, Biological
  • Radioisotope Dilution Technique
  • Spectrophotometry
  • Time Factors


  • 7-hydroxymethyl chlorophyll
  • Carbon Radioisotopes
  • Pigments, Biological
  • Chlorophyll
  • chlorophyll b
  • Chlorophyll A