Enhancing protein stability is important in many biomedical applications and is an appealing approach to emulate nature stabilizing molecular interactions [78]. The covalent disulfide bonds provide substantial stability to target proteins and disulfide engineering had achieved considerable success in broad range of applications [33]. In total, 11 pairs of residues were selected for the purpose of disulfide engineering. These include Met1-Ser81, Lys5-Ala59, Val12-Asp28, Ser16-Asp28, Thr40-Ser47, Val73-Gln77, Ala119-Ala133, Met122-Ala133, Ala126-Asp129, Leu156-Leu163, and Asn159-Asp162. The average Chi3 and energy value for the pairs is 12.54 (max, 108.65 and min, -110.64) and 3.12 (max, 4.39 and min, 1.14). The disulfide engineered MEPVC structure is presented in Figure 5 .
Fig. 5 Disulfide engineering of the MEPVC. The yellow spheres represent mutated residues.