Effects of Mild Trypsin Treatment on the Passive Tension Generation and Connectin Splitting in Stretched Skinned Fibers From Frog Skeletal Muscle Muscle

When skinned fibers from frog semitendinous muscle were mildly treated with trypsin, passive tension generation was remarkably reduced, and the hydrolysis of a-connectin to ,8-connectin simultaneously occurred. On immunoelectron microscopy, splitting of the connectin filaments at the A-I junction area in a sarcomere was seen. These observations strongly suggest that connectin filaments are responsible for passive tension generation as a parallel elastic component in a sarcomere.