Mj. Zhou et N. Panchukvoloshina, A ONE-STEP FLUOROMETRIC METHOD FOR THE CONTINUOUS MEASUREMENT OF MONOAMINE-OXIDASE ACTIVITY, Analytical biochemistry, 253(2), 1997, pp. 169-174
We have developed a one-step fluorometric method for the measurement o
f monoamine oxidase (MAO) activity in 96-well microplates with sensiti
vity 10-fold higher than the conventional spectrophotometric assay met
hod. This assay is based on the detection of H2O2 in a horseradish per
oxidase-coupled reaction using N-acetyl-3,7-dihydroxyphenoxazine (Ampl
ex Red), a highly sensitive and stable probe for H2O2. With a single s
ampling, this assay is useful for performing both end-point and contin
uous measurements of MAO activity. Using a commercially available enzy
me, our assay allows the detection of MAO B activity as low as 1.2 x 1
0(-5) U/ml. When applied to crude tissue homogenates, we have been abl
e to selectively detect both MAO A and MAO B from cow brain tissue wit
h protein content as low as 200 mu g per sample. The potential applica
tions of this assay include the measurement of MAO activity in normal
and diseased tissues, blood samples, and other biological fluids and t
he screening of drugs for the treatment of MAO-mediated diseases. (C)
1997 Academic Press.