Protein Engineering with Non-Natural Amino Acids

Protein Design: Toward Functional Metalloenzymes

“…A number of broad applications of noncoded amino acids have been recognized in designed proteins with improved biophysical properties or novel functions. 734–737 The incorporation of unnatural amino acids in these de novo designed constructs is straightforward due to the application of solidphase peptide synthesis techniques.…”

The synthesis of [14C]4‐acetylphenylalanine, effect on cell viability, and assessment of protein incorporation in male rat hepatocytes

“…PEGylation is a proven approach to prolonging the duration of action and enhancing biophysical solubility and stability of peptides, but polyethyleneglycol (PEG) has to be at a specific site in the protein, otherwise it might lead to loss in bioactivity . 4‐Acetylphenylalanine or para ‐acetylphenylalanine (pAcF) is a novel amino acid with a ketone side chain that is uniquely reactive in proteins . The ketone functionality can react with an aminooxy functionalized PEG polymer to form a stable oxime adduct of the protein as demonstrated in Scheme .…”

“…5,6 The ketone functionality can react with an aminooxy functionalized PEG polymer to form a stable oxime adduct of the protein as demonstrated in Scheme 1. 6,7 One concern with using unnatural amino acids, such as 4-acetylphenylalanine, is the possibility of it being cleaved from the peptide and becoming incorporated into endogenous proteins. To determine whether this occurs or not, an in vitro experiment to assess the cell viability and amino acid incorporation into endogenous proteins using primary male rat hepatocytes was envisioned using [ 14 C]4-acetylphenylalanine with comparison to [ 14 C(U)]Lphenylalanine.…”

“…4‐Acetylphenylalanine or para ‐acetylphenylalanine (pAcF) is a novel amino acid with a ketone side chain that is uniquely reactive in proteins . The ketone functionality can react with an aminooxy functionalized PEG polymer to form a stable oxime adduct of the protein as demonstrated in Scheme . One concern with using unnatural amino acids, such as 4‐acetylphenylalanine, is the possibility of it being cleaved from the peptide and becoming incorporated into endogenous proteins.…”

Non-canonical amino acids bearing thiophene and bithiophene: synthesis by an Ugi multicomponent reaction and studies on ion recognition ability

“…Recent reports include the application of such amino acids in studies of molecular flexibility and protein folding, substrate binding activity of proteins, antigenicity or enzymatic activity, targeting peptides for molecular imaging, peptidomimetics biological activity and protein engineering (Kajihara et al 2006; Hennig et al. 2007;Katritzki and Narindoshvili 2009;Lee et al 2010;Wang et al 2012;Pless and Ahern 2013;Niu and Guo, 2013;Liu et al 2015, Zhou et al 2016.Many biochemical processes rely on the coordinating ability that amino acids and peptides display towards metal ions because they possess electron donor atoms like nitrogen, oxygen and sulphur at…”