Partial alanine scan of mast cell degranulating peptide (MCD): Importance of the histidine- and arinine residues

Angeliki Buku, Milton Mendlowitz, Barry A. Condie, Joseph Price

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Abstract

The influence of the two histidine and two arginine residues of mast cell degranulating peptide (MCD) in activity and binding was studied by replacing these amino acids in the MCD sequence with L-alanine. Their histamine releasing activity was determined on rat peritoneal mast cells. Their binding affinity to the FcERIα binding subunit of the human mast cell receptor protein, was carried out using fluorescence polarization. The histamine assay showed that replacement of His13 by Ala occurred without loss of activity compared with the activity of MCD. Alanine substitutions for Arg7 and His8 resulted in an approximately 40-fold increase, and for Arg16 in a 14-fold increase in histamine-releasing activity of MCD. The binding affinities of the analogs were tested by competitive displacement of bound fluorescent MCD peptide from the FcERIα binding protein of the mast cell receptor by the Ala analogs using fluorescence polarization. The analogs Ala8 (for His) and Ala16 (for Arg) showed the same binding affinities as MCD, whereas analog Ala7 (for Arg) and analog Ala13 (for His) showed slightly better binding affinity than the parent compound. This study showed that the introduction of alanine residues in these positions resulted in MCD agonists of diverse potency. These findings will be useful in further MCD structure-activity studies.

Original languageEnglish
Pages (from-to)313-317
Number of pages5
JournalJournal of Peptide Science
Volume10
Issue number6
DOIs
Publication statusPublished - 1 Jun 2004

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Keywords

  • Ala-scan
  • Flourescence polarization
  • Histamine release
  • MCD
  • Mast cell receptor

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