title: Active fragments and analogs of the plant growth factor, phytosulfokine: structure-activity relationships.
abstract: 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.
authors.affiliation: Department of Applied Biological Sciences, Nagoya University Chikusa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsubayashi
authors.forename: H
authors.initials: H
authors.lastname: Hanai
authors.forename: O
authors.initials: O
authors.lastname: Hara
authors.forename: Y
authors.initials: Y
authors.lastname: Sakagami
mesh_terms: D000595:Amino Acid Sequence; D002455:Cell Division / Q000187:drug effects; D007202:Indicators and Reagents; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D036361:Peptide Hormones; D010937:Plant Growth Regulators / Q000737:chemistry / Q000494:pharmacology*; D010940:Plant Proteins / Q000737:chemistry / Q000494:pharmacology*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013329:Structure-Activity Relationship; D014675:Vegetables / Q000166:cytology* / Q000187:drug effects
chemical_list: D007202:Indicators and Reagents; D009842:Oligopeptides; C100975:PSK-alpha protein, plant; D010446:Peptide Fragments; D036361:Peptide Hormones; D010937:Plant Growth Regulators; D010940:Plant Proteins