The function and activity of proteins are directly related to their higher-order structure
(HOS) since the three-dimensional arrangement of the sequence determines which residues
are close in space. A well-studied example of this relationship is the digestive enzyme
α-chymotrypsin, which differs only by four amino acids from its inactive precursor. Yet, the
cleavage of these four residues is known to initiate small but important conformational
changes which give rise to activation of the enzyme. Characterizing those changes in
proteins through 3D-structural analysis requires tremendous effort and crystal structures
are often not representative for the protein structure in the solution of interest. Alternatively,
the secondary structure can be used as a sensitive reporter for changes in the overall
protein arrangement. Here, we employ Microfluidic Modulation Spectroscopy (MMS), an
automated quantum cascade laser (QCL)-based infrared technique, to determine the
structural changes along the activation of α-chymotrypsin in solution. Using the example
of chymotrypsin, the goal of this study is to show that conformational changes in proteins
which may substantially impact their function, can be successfully monitored with MMS.
5 июн 2023
