ABSTRACT
Exoglucanase/cellobiohydrolase (EC 3.2.1.176) hydrolyzes a ß-1,4-glycosidic bond from the reducing end of cellulose and releases cellobiose as the major product. Three complex crystal structures of the glycosyl hydrolase 48 (GH48) cellobiohydrolase S (ExgS) from Clostridium cellulovorans with cellobiose, cellotetraose and triethylene glycol molecules were solved. The product cellobiose occupies subsites +1 and +2 in the open active-site cleft of the enzyme-cellotetraose complex structure, indicating an enzymatic hydrolysis function. Moreover, three triethylene glycol molecules and one pentaethylene glycol molecule are located at active-site subsites -2 to -6 in the structure of the ExgS-triethylene glycol complex shown here. Modelling of glucose into subsite -1 in the active site of the ExgS-cellobiose structure revealed that Glu50 acts as a proton donor and Asp222 plays a nucleophilic role.
Subject(s)
Cellulases/chemistry , Cellulases/metabolism , Cellulose/analogs & derivatives , Clostridium cellulovorans/enzymology , Tetroses/metabolism , Biocatalysis , Calcium/metabolism , Catalytic Domain , Cellulose/chemistry , Cellulose/metabolism , Crystallization , Crystallography, X-Ray , Molecular Docking Simulation , Protein Structure, Secondary , Tetroses/chemistryABSTRACT
OBJECTIVE: Data are lacking on the relationship between postresuscitation ECG and outcome in out-of-hospital cardiac arrest (OHCA). We examined the prognostic information that postresuscitation ECG rhythm can provide for predicting outcome in OHCA survivors. METHODS: The retrospective observational study enrolled 56 successfully resuscitated nontraumatic adult OHCA patients. Postresuscitation 12-lead ECGs of the enrolled patients were interpreted independently by two cardiologists. We compared baseline clinical characteristics, CPR process, and outcome in the 8 patients with postresuscitation accelerated idioventricular rhythm (AIVR, n = 8) and the 48 without AIVR. RESULTS: The AIVR group had a higher proportion of patients with coronary artery disease (50% vs. 15%), initial ventricular tachycardia/fibrillation rhythm (50% vs. 8%), and cardiac origin of OHCA (75% vs. 23%). AIVR patients had longer total CPR duration (32 vs. 18 min) and higher dose of epinephrine use (10 vs. 3 mg). Postresuscitation AIVR was associated with an increased incidence of repeated CPR within 1 h after return of spontaneous circulation (38% vs. 4%), and lower 7-day survival rate (0% vs. 50%). CONCLUSIONS: AIVR on postresuscitation ECG offers a prognostic factor related to a higher repeated CPR rate within 1h after return of spontaneous circulation and a lower 7-day survival rates in successfully resuscitated OHCA victims.
