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Linear, cyclic, and polypeptides having the sequence -Asp-ϵAhx-Ser-ϵAhx-His-ϵAhx- as catalysts in the ester hydrolytic reactions

Authors
Journal
International Journal of Biological Macromolecules
0141-8130
Publisher
Elsevier
Publication Date
Volume
5
Issue
2
Identifiers
DOI: 10.1016/0141-8130(83)90022-3
Keywords
  • Polypeptide
  • Linear-Peptide
  • Cyclic-Peptide
  • Sequence Of-Asp-ϵAhx-Ser-ϵAhx-His-ϵAhx-
  • Catalysis
  • Serine Protease
  • P-Nitrophenyl Acetate (Pnpa)

Abstract

Abstract Box-Asp-ϵAhx-Ser-ϵAhx-His-ϵAhx-OEt(Linear-6), cyclo(-Asp-ϵAhx-Ser-ϵAhx-His-ϵAhx-)(Cyclic-6) and poly(-Asp-ϵAhx-Ser-ϵAhx-His-ϵAhx-)(Poly-6) were synthesized, and their catalytic actions in the hydrolysis of PNPA were investigated. Linear-6 was prepared by fragment condensations of three peptides having the sequence -Asp(OBzl)-ϵAhx-, -Ser(Bzl)-ϵAhx- and -His-ϵAhx-, respectively, and subsequent debenzylation. Cyclic-6 and Poly-6 were obtained by cyclization and polymerization, respectively, of H-Asp(OBzl)-ϵAhx-Ser(Bzl)-ϵAhx-His-ϵAhx-OH with DPPA, and subsequent deprotections. The reaction velocities in the hydrolysis of PNPA were all proportional to [E] or [S], and all peptides gave the bell-shaped pH- κ cat profiles having optima around pH 8.2. The reaction velocity of Cyclic-6 was always larger than that of Linear-6 or Poly-6. The velocities of all reactions increased steadily with rise in temperature, and the Arrhenius' plots from T- k cat relations suggested that the activation energy for the reaction catalysed by Poly-6 is larger than that by Linear- or Cyclic-6. Brief results for the hydrolysis of other substrates, the solvent isotope effect, and the conformational study with c.d. measurements are also reported.

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