Problems with zymography - Running SDS page gels protein wont migrate down the gel (Aug/01/2008 )

I am having problems with zymography, the protein wont migrate down the gel. I am using 7.5% acrlymide/bis gel and running for 2 hours at 100V MW marker is moving down the gel and the sample buffer is running off. can anyone please help

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How big is your protein of interest?

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The proteins are MMP-2 which has a molecular weight of 72-kD and MMP-9 which has a molecular weight of 92-kD

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Do the proteins move down the stacking gel?

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yes they move through the stack fine its just when they reach the resolving gel they seem to halt, the rest of the gel is working my digestion of the substrate is there its just the bands wont move down the gel

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