Structural Model of TB Enzyme (image) Johns Hopkins Medicine Caption This is a 3-D model of the outside surface of the enzyme that helps M. tuberculosis bacteria resist common antibiotics. Blue indicates positively charged atoms; red indicates negatively charged atoms. A peptidoglycan (green) is bound inside the enzyme's active site. Credit Mario A. Bianchet Usage Restrictions None 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.