Three families of thiol peptides are induced by cadmium in maize

Plant J. 1995 Mar;7(3):391-400. doi: 10.1046/j.1365-313x.1995.7030391.x.


Phytochelatins ((gamma GluCys)nGly) are synthesized from glutathione by plants exposed to metals like Cd2+, Cu2+ and Zn2+. An intracellular complex formed by phytochelatins with Cd2+ and sulfide is thought to detoxify the metal possibly by sequestration in the vacuole. It was found that maize seedlings exposed to Cd2+ produced phytochelatins and two additional families of cysteine-containing peptides, (gamma GluCys)n and (gamma GluCys)nGlu. All thiol peptides with n = 2 and 3 were purified and their structure characterized by tandem mass spectrometry. For maize plants exposed to Cd2+ for 7 days, phytochelatins were synthesized preferentially in the first 24 h whereas the amounts of (gamma GluCys)n and (gamma GluCys)nGlu were the highest thereafter. This was probably due to an initial large pool of glutathione available in control plants compared with a dearth of gamma GluCys and no detectable gamma GluCysGlu. The (gamma GluCys)nGlu peptides were induced exclusively by Cd2+ as they were below the detection limit in control seedlings that contained low amounts of phytochelatins and (gamma GluCys)n. Since the Cys moiety of the peptides is essential for binding Cd2+, a role for accumulated (gamma GluCys)n and (gamma GluCys)nGlu in detoxifying Cd2+ in plants must be considered.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acids / analysis
  • Cadmium / pharmacokinetics
  • Cadmium / toxicity*
  • Glutathione / metabolism
  • Inactivation, Metabolic
  • Metalloproteins / biosynthesis
  • Metalloproteins / chemistry
  • Metalloproteins / genetics
  • Molecular Sequence Data
  • Molecular Structure
  • Peptide Biosynthesis*
  • Peptides / chemistry
  • Peptides / genetics
  • Phytochelatins
  • Plant Proteins / biosynthesis
  • Plant Proteins / chemistry
  • Plant Proteins / genetics
  • Zea mays / drug effects*
  • Zea mays / genetics
  • Zea mays / metabolism*


  • Amino Acids
  • Metalloproteins
  • Peptides
  • Plant Proteins
  • Cadmium
  • Phytochelatins
  • Glutathione