Single- or Dual-Mode Switching of Semisynthetic Ribonuclease S′ with an Iminodiacetic Acid Moiety in Response to the Copper(II) Concentration

Abstract

Abstract:Ribonuclease S' bearing iminodiacetic acid as a metal-binding site was designed and semisynthesized by self-assembly of native S-protein with chemically modified S-peptide. Iminodiacetic acid-appended amino acid (Ida 4 ) was synthesized and incorporated into the S-peptide sequence by solid-phase peptide synthesis based on Fmoc chemistry at a single site or double sites of the solvent-exposed side of the S-peptide. Circular dichroism (CD) spectroscopy of these S-peptides confirmed that the Cu II ion induced an increase or decrease of a-helix conformation depending on the replacement position. S-Peptide/Sprotein titration monitored by conventional enzymatic activity and UV or CD spectroscopy demonstrated that various S-peptides form a stable complex (Ida 4 ± RNase S') with S-protein, except when Met13 and Asp14 are replaced with Ida 4

Incorporation of artificial receptors into a protein/peptide surface: A strategy for on/off type of switching of semisynthetic enzymes

“…We planned to investigate the efficiency of the metal-induced conformational change for modulation of the structure and activity of RNase S. A non-natural amino acid bearing an iminodiacetic acid group (Ida 4 ) thus is synthesized to accommodate to the 9-fluorenylmethoxylcarbonyl (Fmoc) strategy of solid phase peptide synthesis and subsequently introduced into S-peptide fragment of RNase by semisynthesis. 25 (See Chart 1. )…”