Characterization of a benzyladenine binding-site peptide isolated from a wheat cytokinin-binding protein: sequence analysis and identification of a single affinity-labeled histidine residue by mass spectrometry.
A wheat embryo cytokinin-binding protein was covalently modified with the radiolabeled photoaffinity ligand 2-azido-N6-[14C]benzyladenine. A single labeled peptide was obtained after proteolytic digestion and isolation by reversed-phase and anion-exchange HPLC. Sequencing by classical Edman degradation identified 11 of the 12 residues but failed to identify the labeled amino acid. Analysis by laser photodissociation Fourier-transform mass spectrometry of 10 pmol of the peptide independently confirmed the Edman data and also demonstrated that the histidine residue nearest the C terminus (underlined) was modified by the reagent in the sequence Ala-Phe-Leu-Gln-Pro-Ser-His-His-Asp-Ala-Asp-Glu.
Brinegar
A C
AC
ARCO Plant Cell Research Institute, Dublin, CA 94568.
Cooper
G
G
Stevens
A
A
Hauer
C R
CR
Shabanowitz
J
J
Hunt
D F
DF
Fox
J E
JE
D000225:Adenine / Q000031:analogs & derivatives* / Q000378:metabolism; D000345:Affinity Labels; D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D001665:Binding Sites; D002352:Carrier Proteins / Q000032:analysis*; D003583:Cytokinins; D006639:Histidine / Q000032:analysis*; D007701:Kinetin; D013058:Mass Spectrometry; D010940:Plant Proteins; D011687:Purines
D000345:Affinity Labels; D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D002352:Carrier Proteins; D003583:Cytokinins; D010940:Plant Proteins; D011687:Purines; D006639:Histidine; D000225:Adenine; C480551:benzylaminopurine; D007701:Kinetin