Amorphous calcium phosphate.
ACP is a unique calcium phosphate in that it lacks long-range crystalline order. Yet the constancy in the composition of ACP over a wide range of solution conditions suggests a well-defined local structural unit. Although this order within disorder is the most distinguishing feature of ACP, the solution instability of ACP and its ready transformation into crystalline phases such as OCP and apatite may be of greater biological relevance. In particular, the initiating role ACP plays in matrix vesicle mineralization raises the importance of this phase from a mere laboratory curiosity to that of a key intermediate in skeletal calcification.
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Biomaterials Group, Polymers Division National Institute of Standards and Technology, Gaithersburg, Md., USA.
D000818:Animals; D001031:Apatites / Q000737:chemistry; D001842:Bone and Bones / Q000737:chemistry; D002113:Calcification, Physiologic; D002130:Calcium Phosphates / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003102:Colloids / Q000737:chemistry; D003460:Crystallization; D006801:Humans; D006868:Hydrolysis; D007477:Ions; D015394:Molecular Structure; D012995:Solubility
D001031:Apatites; D002130:Calcium Phosphates; D003102:Colloids; D007477:Ions; C519480:amorphous calcium phosphate; C022045:octacalcium phosphate