I am writing to ask you some questions regarding I-TASSER protein modeling server. I have designed a protein sequence which consists of a iRGD motif. As the related papers indicate this motif has two Cys that form disulfide bond to make the motif circular. After protein 3D structure prediction by I-TASSER server, the predicted protein model did not show this disulfide bond. I would like to know if generally the server is able to predict the disulfide bonds. If not, is there any protein structure prediction server which can predict the difulfide bonds?