MedSpace

Why western Blot samples turn yellow and precipitate? Sample appears to be acidic. Bromophenol blue in the loading buffer turns to yellow at acidic pH (below 3). Try to adjust the pH by adding NaOH [ 1 ].  Reason for that is proteins may be getting degraded due to heat exposure. One researcher had the same problem and so instead of keeping samples at 95 ° c  he started warming at 60-65 °  C. So anyone can try it out and as [ 1 ] said check the pH as well of the loading dye [ 2] .  Heating a sample also changes pH. An altered pH is not only responsible to turn the sample color yellow, but may also precipitate the proteins. Keeping SDS containing samples in ice is another common mistake to see this precipitation [ 3 ].  Another researcher said that he has got to do more with the total protein concentration in the lysate. He faced the same problem of precipitation upon denaturation at 100 ° c . He added 1/10th volume of 10% SDS and then boiled. Protein did not precipitate. T

Why reuse primary antibody? Western blotting is one of the most common method for detecting and semi-quantifying specific proteins. The cost of running a Western is predominantly driven by detection antibodies, which are used to probe membrane-bound target protein(s). Although some antibodies can be produced cheaply in-house, most antibodies must be commercially ordered. Reusing antibodies for subsequent Westerns can save your lab a considerable amount of money. So money is nothing but everything. In conclusion economic research practises is  budget friendly and reuse of primary antibody is one of them.  When reuse is problematic? The most standard phospho-antibody protocols involve blocking with 5% milk in PBS or TBS (0.1% Tween 20), followed by a couple washing steps with PBS or TBS to remove the excess milk.  If you dilute your antibody in a milk solution, storage and re-use will be extremely problematic, because the milk will "go bad" and fall out of soluti