Macrocyclic peptide PR Nishant Raj (IMAGE) Indian Institute of Science (IISc) Caption Single atom 'O' to 'S' substitution in cyclic peptides improves their membrane permeability and bioavailability. This study paves the way for developing next-generation peptide-based therapeutics. Credit Nishant Raj Usage Restrictions N/A License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.