Abstract
The incorporation of D-amino acids can influence the structure and enzymatic stability of proteins or peptides, especially when they are introduced at enzyme cleavage sites, significantly inhibiting the enzymatic hydrolysis of peptides. The abnormal accumulation of these peptides has been linked to age-related conditions, including cataracts and Alzheimer’s disease. N-terminal acetylation, an essential post-translational modification, significantly enhances the physicochemical properties of peptides and plays an essential role in regulating their performance within biological systems. This research examined the impact of N-terminal acetylation on the enzymatic hydrolysis of peptides incorporating D-amino acids. Enzymatic activity assessments showed that N-terminal acetylation greatly promoted the enzymatic breakdown of these peptides by Proteinase K (PROK), with the substrate decay rate constant for the acetylated peptide Ac-6-w increasing by 17.5 times. This enhancement was specific to serine-type proteases, which exhibited a comparable cleavage pattern. Molecular docking further demonstrated that N-terminal acetylation improved interactions within the catalytic triad of serine proteases, leading to faster enzymatic degradation. The results provide novel insights into the impact of N-terminal acetylation on the enzymatic behavior of peptides incorporating D-amino acids, and they propose a potential approach for targeting these peptides to preserve normal physiological functions.
