| Abstrakt: |
A simple, straightforward method for differentiating asparaginyl (or glutaminyl) dipeptides from aspartyl (or glutamyl) dipeptides is described. The technique involves two separate methods to form methyl esters. The first, employing 0.1 nHCl/methanol at room temperature for 4 hr, reveals all dipeptides except nonvolatile Asn-and Gln-containing dipeptides. The second procedure, with 0.1 nHCl/MeOH at 45°C for 16 hr, solvolyses the Asn/Gln residues, and new pairs of Asp or Glu dipeptides occur. This approach proved feasible with a synthetic pentadecapeptide, scotophobin, containing Asn-Asn and Gln-Gln as part of its primary structure. |
