Conformational study of the basic proline‐rich polypeptides from human parotid saliva

Abstract

The conformational study of two basic proline-rich polypeptides from human parotid saliva, P-D and P-E of known primary structures, was performed by CD and ' H-n.m.r. spectra measurements. These polypeptides contain consecutive sequences of five prolyl residues in their amino acid sequences. The troughs in CD spectra of P-D and P-E were found at 202 and 201nm, respectively. These wavelengths were different from the value of 206 nm of poly-L-proline form I1 conformation. In spite of this, the existence of poly-Lproline form I1 conformation was suggested in the structure of P-D, because the trough for a fragmental peptide of P-D containing five consecutive prolyl residues was found at 204 nm.No remarkable change was detected in CD and 'H-n.m.r. spectra of P-D and P-E in the range of pH 3.0--11.0. The result suggests that no folding of polypeptide which might be affected by ionic interaction exists in its structure.

Synthesis and conformational analysis of salivary proline‐rich peptide P‐B

“…A poor homology over the entire range of sequence and the absence of a template protein poses problems for homology modeling of P-B. The problem was overcome by building a chimera model, based on the coordinates of fragments of four different proteins (1q7d: 11-20; 2dou: 339-353; 1eys: 96-107 and 2v8f: [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] found in the Protein Data Bank, using BLASTP 2.2.22 [30]. The sequential homology between appropriate fragments of P-B and their homolog structures is about 60% (Figure 1).…”

“…Results of conformational studies of PRPs suggested the occurrence of the poly-L-proline form II conformation. However, there are still some discrepancies in the interpretation of conformations of this line of peptides in solution [9][10][11].…”