Enzyme-specific activation versus leaving group ability.
Bottom Line: Enzyme-specific activation and the substrate mimetics strategy are effective ways to circumvent the limited substrate recognition often encountered in protease-catalyzed peptide synthesis.A key structural element in both approaches is the guanidinophenyl (OGp) ester, which enables important interactions for affinity and recognition by the enzyme--at least, this is usually the explanation given for its successful application.In this study we show that leaving group ability is of equal or even greater importance.
Affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.Show MeSH
Mentions: Inspection of the molecular model of trypsin with Z-Gly-O3G revealed that there is space in the binding pocket for the introduction of a small substituent (Figure 2), such as a methylene (O3G=) or two fluorides (O3GF2), which are weak and strong inductively electron-withdrawing groups, respectively. However, these modifications also create additional van der Waals interactions with the pocket, which by themselves can be a reason for increased affinity of the ester for the enzyme. To assess this effect, a cyclopropyl group was included (O3G∇), which was shown to fit in the binding pocket to make these additional interactions without altering the electronic properties.
Affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.