Hey,

I am currently trying to quantify membrane bound alkaline phosphatase from bone cells, so instead of trying some fancy ELISA assay, I wanted to give a biochemical (p-nitrophenol phosphate) assay a go, with some good results, but am a bit stuck in the quantitation of colour development at 405 nm ( I do get a progressive yellow colour development, which should obey 1st order kinetics) but several questions arose:

- how do I apply the Lambert-Beer law : if I don't know what my (a) optical pathlength is (plate assay with 100 microl) ( the extinction coefficient at the pH I am using (10.4) . Is mg or units per mg total protein the way to express my results best? mg of alp?


I really would appreachiate some help


Garrit

( the extinction coefficient at the pH I am using (10.4) . Is mg  or units per mg total protein the way to express my results best? mg of alp?