11740
Measurement of proton pumping stoichiometry is challenging because , even in isolated mitochondria , it is difficult to measure the proton motive force while simultaneously measuring the redox potentials of the NADH / NAD ( + ) and ubiquinol / ubiquinone pools .
 Chemical: NADH; Chemical: NAD ( + ); Chemical: ubiquinol; Chemical: ubiquinone
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: NADH; Chemical: NAD ( + ); Chemical: ubiquinol; Chemical: ubiquinone