Active fragments and analogs of the plant growth factor, phytosulfokine: structure-activity relationships

Biochem Biophys Res Commun. 1996 Aug 5;225(1):209-14. doi: 10.1006/bbrc.1996.1155.


Sulfated pentapeptide phytosulfokine-alpha (PSK-alpha) is the first chemically characterized peptidal plant growth factor that induces proliferation of the mesophyll cells of asparagus. To determine the active core involved in the sequence PSK-alpha, we synthesized PSK-alpha and twelve PSK-alpha analogs by the solid phase peptide synthesis and the direct sulfation to the peptide-resin using dimethylformamide-sulfurtrioxide (DMF-SO3) complex. The truncated analogs of PSK-alpha without the first and second C-terminal amino acids retained 8% and 20% of the activity of the parent pentapeptide, respectively. Deletion of the sulfate groups of Tyr1 and Tyr3 resulted in compounds with 0.6% and 4% of the activity of PSK-alpha, indicating that the sulfate group of Tyr1 is more important than that of Tyr3 for the expression of its activity. In contrast, the N-terminal truncated analog and unsulfated analog exhibited little or no activity. Thus the N-terminal tripeptide fragment H-Tyr(SO3H)-Ile-Tyr(SO3H)-OH has been identified as the active core of PSK-alpha.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Division / drug effects
  • Indicators and Reagents
  • Molecular Sequence Data
  • Oligopeptides / chemical synthesis
  • Oligopeptides / chemistry
  • Oligopeptides / pharmacology*
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / chemistry
  • Peptide Fragments / pharmacology*
  • Peptide Hormones
  • Plant Growth Regulators / chemistry
  • Plant Growth Regulators / pharmacology*
  • Plant Proteins / chemistry
  • Plant Proteins / pharmacology*
  • Spectrometry, Mass, Fast Atom Bombardment
  • Structure-Activity Relationship
  • Vegetables / cytology*
  • Vegetables / drug effects


  • Indicators and Reagents
  • Oligopeptides
  • PSK-alpha protein, plant
  • Peptide Fragments
  • Peptide Hormones
  • Plant Growth Regulators
  • Plant Proteins