In the study by Avery, MacLeod, and McCarty, what treatment was used to destroy the transforming factor?

In the study conducted by Avery, MacLeod, and McCarty, the transforming factor was identified as DNA. To demonstrate this, they performed a series of experiments where various enzymes were used to treat different samples. The use of deoxyribonuclease (DNase) was crucial because this enzyme specifically hydrolyzes DNA, effectively destroying the transforming ability of the extract. When the DNA was degraded by DNase, the transformation of non-virulent bacteria into virulent bacteria could not occur, confirming that DNA was indeed the genetic material responsible for the transformation.

The other treatments addressed different components of the cell and their potential roles in transformation. For instance, protease would degrade proteins, ribonuclease would target RNA, and heating would denature proteins but would not selectively eliminate DNA. The success of deoxyribonuclease in abrogating the transforming factor highlights the critical role of DNA in heredity and transformation, which was pivotal in advancing the understanding of molecular genetics.