Final answer:
Avery, MacLeod, and McCarty used enzymes such as protease, RNase, and DNase in their experiments to deduce that DNA was the transforming principle in bacterial transformation.
Step-by-step explanation:
In the Avery, MacLeod, and McCarty experiments, the enzymes used were specific for degrading proteins, RNA, and DNA. They carried out a series of experiments to identify the transforming principle, which could transform nonpathogenic R strain bacteria into pathogenic S strain bacteria. By systematically eliminating each type of molecule, they found that protease treatment, which degrades proteins, and RNase treatment, which degrades RNA, did not prevent transformation.
However, when DNase, the enzyme that degrades DNA, was added to the extract, the transforming ability was lost. This provided strong evidence that DNA was responsible for the transformation, leading them to conclude that DNA was indeed the transforming principle, supporting the concept that DNA is the molecule of heredity.