Preferential hydroxylation of type IV collagen by lysyl hydroxylase from Ehlers-Danlos syndrome type VI fibroblasts

Normal and Ehlers-Danlos syndrome type VI human skin and cornea fibroblasts were assayed for lysyl hydroxylase activity using two different collagen types as substrates. The enzyme from normal fibroblasts hydroxylated type I collagen more readily than type IV collagen. In the diseased cells the enzyme activity was significantly reduced, and the residual activity was preferentially directed towards type IV collagen. This suggests the existence of isoenzymes of lysyl hydroxylase or an alteration in the Ehlers-Danlos syndrome type VI that affects the binding of type I collagen more than that of type IV collagen.