Non-coded amino acids

Since the stereochemistry of the newly created quaternary carbon center was apparently determined in the second alkylation process, the core of this method should be applicable to the asymmetric alkylation of aldimine Schiffbase 42 derived from the corresponding a-amino adds. Indeed, di-alanine-, phenylalanine- and leucine-derived imines 42 (R1 = Me, CH2Ph, i-Bu) can be alkylated smoothly under similar conditions, affording the desired non-coded amino acid esters 43 with excellent asymmetric induction, as exemplified in Table 5.7 [19]. 

Current nomenclature recommendations (see footnote to Table 1.1) allow a number of abbreviations to be used for some non-coded amino acids possessing trivial names (some of which are used above and elsewhere in this book) Dopa, [3-Ala, Glp, Sar, Cya, Hey (homocysteine) and Hse (homoserine) are among the more common. 

Non-protein amino acids , alias non-proteinogenic amino acids or non-coded amino acids ... 

Its use with bradykinin and desmopressin (Zubarev et al., 1994), illustrated as a case study below, shows the benefits of MS sequence analysis. The latter peptide, desmopressin ( Minirin , a neurohypophysial hormone analogue), involves a disulphide link and a C-terminal amide, as well as a non-coded amino-acid residue (Mpa = mercaptopropionic acid) and these features can be identified by chemical sequencing methods (Chapter 5) only with considerable effort. 

Jonsson, J., Eriksson, L., Hellberg, S., Sjostrom, M. and Wold, S. (1989) Multivariate parametrization of 55 coded and non-coded amino acids. Quant. Struct. -Act. Relat., 8, 204-209. 

Haidar, D. Maji, S.K. Sheldrick, W.S. Banerjee, A. First crystallographic signature of the highly ordered supramolecular helical assemblage from a tripeptide containing a non-coded amino acid. Tetrahedron Lett. 2002, 43. 2653-2656. 

Maji, S.K. Drew, M.G.B. Baneijee, A. First crystallographic signature of amyloid-like fibril forming 0-sheet assemblage from a tripeptide with non-coded amino acids. Chein. Commun. 2001. 1946-1947. 

Preparation of Pure CdSs Structures in Coiled Coils Using Non-coded Amino Acids... 

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