3L31 CRYSTAL STRUCTURE OF THE CBS AND DRTGG DOMAINS OF THE REGULATORY REGION OF CLOSTRIDIUM PERFRINGENS PYROPHOSPHATASE COMPLEXED WITH THE INHIBITOR, AMP HYDROLASE, CLOSTRIDIUM PERFRINGENS, FAMILY II, INORGANIC, PYROPHOSPHATASE, CBS DOMAIN, BATEMAN DOMAIN, AMP, DRTGG