Hi, i am trying to measure the activity of an enzyme called alanine aminotransferase in plant tissue (sorghum shoots and roots). The assay i am using monitors NADH oxidation: when enzyme activity is higher, NADH is oxidized, so its concentration in the reaction decreases. I have done a kinetic assay and obtained the delta absorbance value (dA/min) at 340 nm (5 minutes total, 9 second intervals); my question is: how do i convert the dA/min value to micromol/ microgram protein/ minute??? Do i have to make a NADH standard curve or is there any formula? I am very confused and would really appreciate if someone could help me.
Thanks in advance,