Epsilon-V1-2, a Cys-conjugated, is a biologically active peptide known as the εPKC-specific inhibitor. It hampers εPKC functionality by obstructing its translocation and the phosphorylation of MARCKS, additionally perturbing εPKC's interaction with its anchoring protein, εRACK. The peptide includes a cysteine residue at its C-terminus, facilitating the formation of potential disulfide bonds with carrier proteins. Pyroglutamyl formation can occur spontaneously at the N-terminus if glutamine or glutamic acid is present, enhancing peptide stability against gastrointestinal proteases. Pyroglutamyl peptides, a recognized subset, are accounted for in the peptide's purity during HPLC analysis.