The unit of activity is defined as the number of Mole or mM or microM of product formed per unit time. The unit of time may also very from h to s. Anyway, after multiplication of the [P] by 1000 it becomes micromole per liter i.e. microM when divided by MW. So, the formula seems to be OK.

Lipase activity assays could be performed as described by Ruiz et al. (FEMS Microbiol. Lett. (2002) 217, 263-267). In this case, lipase mediated hydrolysis reaction of p-nitrophenyl butyrate has been used with formation of p-nitrophenol. One unit of lipase activity was defined as the amount of enzyme that released 1 μmol of p-nitrophenol per minute under the assay conditions used.

Time appears to be too long. The substrate is sensitive to autoclevage without enzyme catalysis. So I would reduce the time app. 5 min.

okay...

Thankyou for the answer..

It is very helpfull..

thankyou

Dont have idea about the formula given by you. But you can use the following:

Lipase activity (U/ml)=[Final assay volume (μL)×OD at 400 nm (cm-1)]

÷[∈ ×time (min)×enzyme taken (ml)]

Where, = Molar extinction coefficient of p-nitrophenol (mM-1. cm-1)

For ∈ see the attached file.