as for time- how long is too long? Some enzymes have "star" activity, they start cutting non-specifically if at too high concentration or if left too long, I'm not sure if Bam HI has it though. I don't think there are any specific requirements for cutting PCR products.
To get rid of your enzyme you can ethanol precipitate your mixture.
normally strange band shape is to do with the gel, for example agarose not dissolving properly before you por so there are clumps, or setting slightly before you pour- again causing small clumps that would cause the sample to run unevenly. Try decreasing the agarose conc and make sure it all dissolves properly. It could theoretically be a problem with your power supply, but then you'd get a strange pattern all over your gel, not the same for all bands.
A his-tag is a technique used in biochemistry to purify proteins. The protein to purify is expressed as a fusion protein, carrrying a series of histidine residues at either the amino or the carboxyl end. The name-giving histidine residues will stick to a nickel surface, and can be eluted from there via imidazol. His-tagged proteins can also be identified on a Western blot via á-his-antibodies.
Myc tags are similar.
I'm trying to find a plasmid vector with some sort of a detectable product that has no sp1 sites in its promoter, as I'm trying to monitor the effect of sp1 on my gene of interest and want to find a plasmid I can use as a transfection efficiency control.
Thanks for any suggestions!
just wondering, when you do ELISA do you dilute your samples to a uniform total protein concentration and then do the assay, or is it ok to use eg. a constant volume of sample and then work out the concentration of protein of interest later, based on a Bradford?