Can saliva enzymes break down skin?

Since Saliva works in the digestive process, Can our skin be broken down though repetitive exposure to saliva? (exp:thumb sucking). Does the break down process in saliva effect genitals in oral sex? Maybe by breaking away at the skin? It is said saliva is capable of killing sperm cells. I also imagine oral enzymes may mute, nerves, or sensitivity in the genitals though consistency of oral sex. Is this plausible?