Glycerol is used in the concentration and storage of enzymes. Also prevents back-diffusion and protein samples into the buffer. Glycerol is used both in sample preparation and gel formation for polyacrylamide gel electrophoresis. Glycerol (5-10%) increases the density of a sample so that the sample will layer at the bottom of a gels sample well. Glycerol is also used to aid in casting gradient gels and as a protein stabilizer and storage buffer component.