Lysyl oxidase: a pituitary hormone-dependent enzyme.

Aldehyde-deficient non-crosslinked collagen obtained from lathyritic rats and collagen from penicillamine-treated rats, which is not deficient in aldehydes but the crosslinking of which is also inhibited, were implanted into the peritoneal cavity of hypophysectomized rats using the diffusion chamber technique. The enzyme lysyl oxidase which catalyses the aldehyde formation in certain lysyl residues of collagen and elastin was extracted from the skin of hypophysectomized rats. The activity of the enzyme was determined following its incubation with an L-[4,5-3H] lysine-labeled elastin substrate prepared from aortas of 17-day-old chick embryos. The result showed that the aldehyde deficient collagen did not crosslink while in the hypophysectomized animal indicating the lack of active lysyl oxidase in the rats. The enzyme activity in the skin of hypophysectomized animals was markedly reduced as compared with the controls indicating directly the dependance of lysyl oxidase activity on pituitary gland hormones.