Site-directed conjugation of nonpeptide groups to peptides and proteins via periodate oxidation of a 2-amino alcohol. Application to modification at N-terminal serine

Abstract

The 2-amino alcohol structure -CH(NH2)CH(OH)- exists in proteins and peptides in N-terminal Ser or Thr and in hydroxylysine. Its very rapid oxidation by periodate at pH 7 generates an aldehyde in the peptide and is the first step in a method for site-directed labeling with biotin or a fluorescent reporter. The modifying group is a hydrazide, RCONHNH2, which reacts with the new aldehyde to form a hydrazone-peptide conjugate, RCONHN = CH-peptide. Experiments with two synthetic peptides, Ser-Ile-Gly-Ser-Leu-Ala-Lys and Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly, and with recombinant murine interleukin-1 alpha (an 18-kDa cytokine with N-terminal Ser) demonstrated this method of peptide tagging. The use of a low molar ratio of periodate to peptide minimized the potential for side reactions during the oxidation, and the desired oxidation was rapid and highly specific. The hydrazones formed were stable at pH 6-8 for at least 12 h at 22 degrees C, but were labile at more acidic pH values. Potential uses of this method include the attachment of biotin, reporter groups, metal chelating groups, imaging agents, and cytotoxic drugs to peptides.

In-depth research of multidrug resistance related cell surface glycoproteome in gastric cancer

“…Many factors may cause this complexity. Firstly, the N-terminal Thr and Ser residues can also be oxidized by periodate and captured onto the hydrazide resin [38]. Actually, 19 O-linked glycoproteins were found among the Swiss-Prot annotated glycoproteins by analyzing the non-glycopeptide fraction.…”

Selective chemical protein modification

“…Among the earliest was the discovery that periodate oxidation (cleavage) of N-terminal Ser/Thr residues led to a terminal aldehyde, which could then react selectively with a fluorescent hydrazine to allow site-specific protein tagging 144 . The group of Francis 145 has utilized a biomimetic PLP-mediated transamination to generate N-terminal ketones.…”

A Fully Solid-Phase Synthesis of Biotinylated Glycoclusters

“…This requires the incorporation of an aminooxy function into sugar derivatives as well as complementary electrophilic function on the template [18,30]. In order to prevent oxida- tion of biotin during the formation of aldehydes from serine residues [38], we introduced levulinic acid to provide a methyl ketone, despite the moderate coupling yields that we observed previously with oxyamines [18]. The removal of pNZ group from 5 was realized by treatment of the resin with a solution of SnCl 2 2M, Phenol 0.01M, AcOH 1.6mM in DMF to release four lysine side chains [21].…”