Measurement of enzymatic activities in turbid suspensions by double beam spectrophotometry

A method for the determination of enzyme activities in turbid suspension is described, based on the use of a double beam or double wavelength spectrophotometer in one or two cell mode. It measures the disappearance of NADH, coupled to the activity of the enzyme, at a 340 wavelength or at a 340 minus 374 mmu wavelength pair. The method has been applied to the determination of pyruvate kinase activity, in the presence of isolated mitochondria, and other possible applications are discussed.