Luciferase Assay!

Hi all,
1. I am doing Luciferase assay to understand transcriptional regulation. I
was looking for proper reporter lysis buffers.
i found out one with KH2PO4 (7.8 pH) with 0.2% Triton X-100 (v/v)..is there
any better?
it takes time for us to order promega 5x reporter lysis buffer.

2. i am doing duplicate assays in 6 well plates..and collecting cells in pbs
and lysing them in 200uL buffer. however i am not sure what is the
"standard" lysate:luciferase substrate (roche) proportion.
i have tried 10uL:90uL, 40uL:60uL, 100:100uL combinations, later gives me
better RLUs
we use a stand-alone, tube-luminometer (sirius), and do not use injectors.

please let me know.
(i will post my questions on DLuciferase Assay also..soon )

thanks in advance
sudheendra.

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