Isoamyl alcohol is an anti foaming agent and stabilizes interphase (coagulated proteins) between the aqueous (DNA) and organic phase (Lipids). It also helps in the precipitation of proteins and carbohydrates.
I expect that you are utilizing the conventional Phenol:chloroform technique to isolate the DNA from the proteins and different tissue/cell flotsam and jetsam. On the off chance that you basically utilize chloroform without anyone else, it froths up and makes it hard to legitimately clean the DNA. Isoamyl liquor shields it from frothing. We used to utilize what we called PC8 - Phenol (cushion immersed with TrisCl, pH 8.0):choloroform:Isoamyl liquor, at a proportion of 25:24:1. It works great, in spite of the fact that you would need to be watchful about material that crossed the interface and would 'drag' phenol and garbage up into the pipet while you were pulling off the watery layer - preferred to lose some example over taint it like that. It was additionally to some degree dubious to make, and requested a specific measure of care, as I discovered one day when I inadvertently dumped 2L of PC8 in my lap since it 'overflowed out' from under the cover while I was shaking the container and made it excessively elusive, making it impossible to clutch. A scientist's jacket doesn't help when the open container skips out of the smoke hood and grounds in your lap! Fortunately I didn't pass on, in spite of the fact that the agony was quite amazing, and some way or another I figured out how to escape with no obvious organ harm despite the fact that I was pissing darker for right around seven days. We don't utilize phenol-based DNA refinement any more.