Interferon is a protein. It is dried into a powder which should be able to be frozen with no problem. But when proteins are dissolved into a liquid solution, freezing can be tricky. As a scientist working with a variety of proteins, I can tell you that many proteins will start to break down if frozen more than once. And rapid freezing is preferable to slow freezing. At home, the closest thing to rapid freezing could be done by putting the protein tube into ice in the back of the freezer lowering the temp more rapidly than if you just stick it on the shelf in the freezer. Proteins also generally survive freezing better if they are more dilute and freezing in smaller portions will allow the freezing to go faster than freezing in big portions.
If a protein is degraded by freezing, it's structure starts to unwind. Some molecules of the protein in the solution may degrade and others won't so you may still see that the protein has some activity or it may lose all activity. You might see some precipitate in the solution (always a bad sign) or you might not. Without some kind of activity readout, it seems impossible to me to know whether freezing is causing a problem. In summary, I would make up the solution to the appropriate dilution and freeze it in the smallest portions that will work (need appropriate sized containers) in the coldest part of the freezer in ice. _______________________________________________ Felvtalk mailing list Felvtalk@felineleukemia.org http://felineleukemia.org/mailman/listinfo/felvtalk_felineleukemia.org