Collagenase and other proteinases in the cornea of the retinol-deficient rat.

1. Enzymes that may contribute to liquefaction of the cornea in retinol-deficient animals and in man have been studied using rat cornea. The established technique of culturing tissue fragments and determining the activity of collagenase (EC 3-4-24-3) and other enzymes in the medium after different periods of culture was used. 2. A collagenolytic system was detected in the media from cultures of rat corneas. This system probably consists of at least two enzymes, a collagenase and a neutral proteinase. 3. Both proteolytic and specific collagenolytic activity were greater in media from retinol-deficient rat corneas. The hydroxyproline level increased in parallel with the increase in enzyme activity. 4. In the final stages of retinol deficiency the cornea is invaded by granulocytes and other cells of the blood and we suggest that destruction of cornea collagen may be due largely to the activity of the enzymes from these cells.