The 'Volume Control' in Green Sulfur Bacteria (image) Washington University in St. Louis Share Print E-Mail Caption The cysteines (yellow) quench photosynthesis by stealing electrons from neighboring chlorophylls (big green molecules). Credit Orf et al. Usage Restrictions please credit Share Print E-Mail 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.