(IMAGE) Deutsches Elektronen-Synchrotron DESY Caption The photosystem II cycle has four steps. There is a large conformation change between status S1 and status S3, as shown by the new inverstigations. Credit Shibom Basu/Arizona State University Usage Restrictions Free for use by the media when reporting on the related paper. Credit must be given. License Licensed 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.