Mass spectrometric and chemical stability of the Asp‐Pro bond in herpes simplex virus epitope peptides compared with X‐Pro bonds of related sequences

Abstract

The mass spectrometric analysis of the immunodominant epitope region (273-284) of herpes simplex virus type 1 (HSV-1) glycoprotein D (gD) showed a favoured fission at the Asp-Pro peptide bond. The fast atom bombardment collision induced dissociation (FAB-CID) study of closely related X-Pro peptides documented that neither the length nor the amino acid composition of the peptide has a significant influence on this preferential cleavage. At the same time the DP bond proved to be sensitive to acidic conditions in the course of peptide synthesis. These observations prompted us to compare the chemical and mass spectrometric stability of a new set of nonapeptides related to the 273-284 epitope region of gD, i.e. SALLEDPVG and SALLEXPVG peptides, where X = A, K, I, S, F, E or D, respectively. The chemical stability of these peptides during acidic hydrolysis was investigated by electrospray ionization mass spectrometry (ESI-MS) and the products were identified by ESI-MS and on-line high performance liquid chromatography-mass spectrometry (HPLC-MS). The mass spectrometric fragmentation and bond stability of the untreated peptide samples were also studied using ESI-MS and liquid secondary ion mass spectrometry (LSIMS). Both the chemical hydrolysis and the mass spectrometric fragmentation showed that the Asp-Pro bond could easily be cleaved, while the KP bond proved to be stable under both circumstances. On the other hand, the XP bond (X = A, I, S, F or E) fragmented easily under the mass spectrometric conditions, but was not sensitive to the acidolysis.

A novel cross‐linked RNase A dimer with enhanced enzymatic properties

“…The amide cross‐link also appears to be labile under conditions used in ionization for mass spectrometric analysis. This is not unexpected as strained bonds have been shown to have chemical instabilities under gas phase acidic vaporization induced by mass spectrometric methods 44, 45. The covalent cross‐linking of RNase A using the in vacuo method does not appear to affect the overall fold of the monomeric units as evidenced by the CD studies (Fig.…”

Elucidation of Two Major Aggregation Pathways in an IgG2 Antibody

“…Peptide bond cleavage at Asp-Pro sequences has been well studied in model peptides and proteins. 30,31 In Asp-Pro sequences, spontaneous cleavage of the peptide bond may occur involving a cyclic anhydride since the peptide bond nitrogen cannot be deprotonated in order to form the succinimide intermediate. 30,32 The clipped heavy chain content in dimer is somewhat higher (58%) compared to that in the HMW aggregate (52%).…”

Factors Governing the Thermal Stability of Lasso Peptides

“…This behavior arises from the presence of an Asp–Pro sequence in the tail regions of these lasso peptides that is known to autocatalyze the self‐hydrolysis of peptides by facilitating the formation of a cyclic imide intermediate. However, this behavior is independent of the peptide topology and commonly observed for peptides including an Asp–Pro sequence . As such, this self‐hydrolysis is not related to the general thermal stability of the lasso fold per se and could be abrogated by fitting point mutations.…”