Serrapeptase (serratio-peptidase) is a protein-digesting enzyme isolated from the friendly bacterium Serratia E-15 discovered in the Japanese silkworm, and has been used as a nutritional supplement in Europe and Asia for decades. Doctor's Best Serrapeptase 120,000 Spu is formulated with Serrateric, a superior alternative to enteric coating that protects the individual enzyme until it reaches the intestine for optimal absorption.