Dear Hiroki Muramatsu Please find the attached file for your reference

Well try running a native gel or a gradient gel (4%-20%). Denaturing SDS PAGE uses a 5% concentration gel, so a BN page or gradient can be a better choice.

In my laboratory, 12.5% SDS-PAGE electrophoresis is prepared in the following composition:

For the separating gel:

Acrylamide 30%: 5000uL

Tris buffer pH 8.7: 4480 uL

10% PSA reagent: 40uL

SDS 20%: 60uL

Water: 2460uL

TEMED reagent: 10 uL

For the concentrating gel:

Acrylamide 30%: 680uL

Tris buffer pH 6.9: 500uL

10% PSA reagent: 24uL

SDS 20%: 24uL

Water: 2440uL

TEMED reagent: 10 uL

I suggest you take these reference values and from there you can make the relevant calculations to obtain the 4% electrophoresis gel

Regards