Replacement of Tyr62 by Trp in the designer protein Milk Bundle‐1 results in significant improvement of conformational stability

Protein design is currently used for the creation of new proteins with desirable traits. In our lab, we focus on the synthesis of proteins with high essential amino acid content, having potential application in animal nutrition. One of the limitations we face in this endeavor is the achievement of stable proteins in spite of a highly biased amino acid content. We report here the synthesis and characterization of MB-1Trp, a protein with a tailored content in selected essential amino acids. The protein is a Tyr62-Trp mutant of the parent molecule MB-1 described earlier. The new protein is largely helical as per design, is well folded, and has a melting temperature of 55 degrees C. Its resistance to proteolytic degradation compares to that of cytochrome c, a protein of similar size. Design strategy used for MB-1Trp is discussed with regards to its applicability toward the creation of efficient nutritional proteins.