Evaluation of in silico approach for prediction of presence of opioid peptides in wheat

Opioid like morphine and codeine are used for the management of pain, but are associated with serious side effects limiting their use. Wheat gluten proteins were assessed for the presence of opioid peptides on the basis of tyrosine and proline within their sequence. Eleven peptides were identified and occurrence of predicted sequences or their structural motifs were analysed using BIOPEP database and ranked using PeptideRanker. Based on higher peptide ranking, three sequences YPG, YYPG and YIPP were selected for determination of opioid activity by cAMP assay against mu and kappa opioid receptors. Three peptides inhibited the production of cAMP to varied degree with EC50 values of YPG, YYPG and YIPP were 5.3 mM, 1.5 mM and 2.9 mM for mu-opioid receptor, and 1.9 mM, 1.2 mM and 3.2 mM for kappa-opioid receptor, respectively. The study showed that in silico approach can be used for the prediction of opioid peptides from gluten.