Prolyl hydroxylase activity during newt forelimb regeneration.

Prolyl hydroxylase activity was measured to obtain insight into changes in collagen metabolism during forelimb regeneration in the adult newt, Notophthalmus viridescens. Activity increased markedly during the redifferentiative stages, remained elevated during digit formation, and decreased as regeneration neared completion. The greatest activity, seen during early digit formation, represents a 20-fold increase in activity over the level seen in nonregenerating limbs. The profile of enzyme activity correlates with the rate of collagen synthesis and the soluble collagen content of the regenerating tissue. Enzyme extracted from limbs in the early stages of regeneration can be activated in vitro upon preincubation with cofactors; however, preincubation has little, if any, effect on enzyme extracted from limbs at the later digit-forming stages.