Structure and conformation of the monohydrate of N-t-boc-tyrosyl-proline(Boc-Tyr-Pro*H2O)

Article abstract of DOI:10.1007/BF01667042

The structure and conformation of the monohydrate of N-t-boc-tyrosyl-proline (Boc-Tyr-Pro*H2O)(C19H26O6N2*H2O) has been investigated with X-ray crystallographic and spectroscopic methods.Boc-Tyr-Pro crystallized in an extended trans conformation in the space group P2₁2₁2₁ with cell dimensions a=8.566(1), B=9.996(1), c=24.734(1).The conformation of Boc-Tyr=Pro reflex α-helix type prolines.Three intermolecular hydrogen bonds are observed.Crystal water is involved in two hydrogen bonds (to the hydroxyl group of the C-terminal of the proline residue: to the carbonyl group of the t-Boc functionality) while the hydroxyl group of the tyrosyl residue (to the carbonyl group of the amide bond) is involved in one hydrogen bond.The puckering mode of the pyrrolidine ring of the proline residue is similar to what has been previously observed for other proline-containing peptides.Cis-trans isomerism is observed in the NMR spectra of Boc-Tyr-Pro with a predominance for the extended side chain for the tyrosyl residue. KEY WORDS: Dipeptides, proline, NMR,hydrogen bonds.