Figure 4.

Formation and measurement of β-CTX-I neo-epitopes. A) Enzymatic cleavage of type I collagen by cathepsin K (Cat K) generates a cleavage specific noe-epitope. B) Enzymatic cross-linking of two type I collagen proteins with lysyl oxidase (LOX) generates a cross-linkede neo-epitope. C) Isomerization of aspatic acid (Asp) from α to β conformation generates an isomerized neo-epitope. D) Combined triple neo-epitope of β-CTX-I containing specific cleaveage, cross-linking and isomerized conformation. E) Illustration of sandwich ELISA for measurement of β-CTX-I.