Enzyme Crystals (IMAGE) Max Planck Institute for Marine Microbiology Caption CODH/ACS crystals obtained without oxygen. The brown color is coming from the natural metals harboured by the proteins (depicted as orange and green balls in the Figure 2). Credit Max Planck Institute for Marine Microbiology/T. Wagner Usage Restrictions Only to be used in the context of this publication and citing the correct copyright 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.