Selective hydrolysis of the unactivated peptide bond in N-acetylated l-histidylglycine catalyzed by various palladium(II) complexes: dependence of the hydrolysis rate on the steric bulk of the catalyst

Gas‐phase investigation of Pd(II)‐alanine complexes with small native and derivatized peptides containing histidine

“…The m/z value for a second prominent ion was consistent with the mass of a complex in which one of the H 2 O molecules is replaced by MeOH. The appearance of the diaqua complex is particularly important in light of the proposal that it is the initial reactive species in solution‐phase hydrolysis reactions 12. To our knowledge, this is the first demonstration of the generation of this type of diaqua Pd(II) complex in the gas phase.…”

“…Histidine‐Glycine‐Glycine (HGG) was synthesized by the Biochemical Research Service Laboratory at the University of Kansas. The synthesis and characterization of K[Pd(A − ) Cl 2 ] was carried out according to a reported procedure 12. In a typical preparation, K 2 PdCl 4 (326 mg) and alanine (89 mg) were dissolved in 10 mL of water and pH raised to 3 by the addition of 1M KOH.…”

“…Transition‐metal complexes have emerged as promising reagents for cleavage of peptides and proteins 6–10. Many reports have shown that palladium(II) complexes spontaneously bind to the side chains of methionine and histidine residues and cause hydrolytic cleavage of short peptides 11–13. As part of an effort to improve our understanding of metal‐ion mediated amide bond cleavage we have initiated an investigation of gas‐phase complexes composed of Pd(II), ligand, and model peptide substrates because studies in the gas phase provide important information regarding intrinsic (i.e.…”

“…Here, we report the generation by electrospray ionization (ESI) of gas‐phase complexes containing: (a) Pd(II) and deprotonated alanine as a coordinating ligand or (b) ternary complexes composed of Pd(II), alanine and various peptides with an incorporated histidine residue, and the fragmentation of these complexes as generated by collision‐induced dissociation (CID). A number of Pd(II) complexes have been shown to be hydrolytically active in solution 11–13. The Pd(II)‐alanine system chosen for our initial gas‐phase experiments is an example of such a complex, and was selected primarily because amino acids are the basic units of potential hydrolytically active metal ion‐peptide complexes that might eventually be applied to proteome analysis.…”

Metal assisted peptide bond hydrolysis: Chemistry, biotechnology and toxicological implications

“…Pd(II) ions are able also to bind at the His imidazole [43][44][45]. The hydrolysis of di-and tripeptides occurs at the carboxyl side of an anchoring His residue, according to the same pattern as for peptides containing anchoring Cys and Met when [PdCl 4 ] 2− was used [43].…”