Abstract
Three enzymic phenomena, inactivation by oxygen, Q(OO2) measurements of a dehydrogenase system, and hydrolysis of acetyl phosphate by a phosphatase of Clostridium kluyveri, were studied by means of the differential microrespirometer. Respiration of yeast cells was also measured with the same instrument. All results obtained in the four types of study agreed closely with earlier results obtained with the Warburg apparatus. The amount of sample needed was of the order of 1/100 to 1/200 of that necessary for comparable study with the Warburg apparatus. The advantages of the instrument in enzyme isolation and purification studies are discussed.