Assay of Cypridina Luciferase

The amount of Cypridina luciferase is measured with Cypridina luciferin. However, the detection and measurement of a trace amount of the luciferase is extremely difficult, for the reason explained below. 

To assay Cypridina luciferase, 1ml of 10 mM pH 7.0 phosphate buffer containing 0.1M NaCl and 5-10 pi of an aqueous 

If a trace activity is indicated by the luminescence intensity measurement, the following two methods can be used to determine whether the light emission is due to the luciferase or it is an artifact (1) Measure the luminescence intensity with a buffer that contains 1 mM EDTA (add luciferase to this buffer and wait 1 min before mixing with luciferin). If the luminescence was caused totally by luciferase, the light intensity will be decreased to about 20% by EDTA (see Section 3.1.7). (2) Inactivate luciferase by acidifying the sample to pH about 2.0, followed by neutralization with NaHCC 3. Inactivated luciferase should not show any luciferase activity. 

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