Skeletal protein protection: the mode of action of an anti-osteoporotic marine alkaloid, norzoanthamine.

Bone is composed of mineralized collagen fibrils. A marine alkaloid, norzoanthamine, accelerates the formation of a collagen-hydroxyapatite composite and enhances collagen release from an immobilized matrix vesicle model. Norzoanthamine recognizes a peptide chain nonspecifically and stabilizes its secondary structure, and collagen has polyvalent binding sites for norzoanthamine.