Figure.3 (IMAGE) Tokyo Institute of Technology Caption McGlynn explains that the sulfur atom of the APS molecule is reduced by the Apr enzyme, leading to the kinetic isotope fractionation reported in the paper. Credit Photo credit: ELSI Usage Restrictions The image may only be used with appropriate caption or credit. 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.