Dipeptidyl peptidase 1 (DPP1), a member of the dipeptidyl peptidase family, is responsible for hydrolyzing peptide bonds, especially those preceding proline. Its structure includes specific active sites enabling it to recognize and cleave particular substrates. DPP1 is primarily expressed in immune cells like lymphocytes, playing a role in regulating immune responses and inflammation. Moreover, it has a significant role in the development of diseases, such as chronic obstructive pulmonary disease (COPD). The gene expression of DPP1 is tissue-specific, and changes in its activity and expression levels can lead to immune dysfunction and disease onset.