Though many proteins can have different subtypes that share highly similar structures, small structural differences can lead to significant changes in activity and function. Kallikrein proteins are serine proteases that provide a great example of protein subtypes with different structures. Characterizing the structure of Kallikrein proteins can assist in understanding how human proteins are conserved and how they are different from one another. In this study, we used Microfluidic Modulation Spectroscopy (MMS), an automated IR spectroscopy technique based on Quantum Cascade Laser (QCL) technology, to accurately determine the secondary structural makeup of kallikrein proteins. Using this information, the goal of this study is to compare the results to crystal structures and hypothesize what roles sequence similarities and differences play in the overall structure and function of the protein subtypes.