HYDRATED SITES IN BIOGENIC AMORPHOUS CALCIUM PHOSPHATES - AN INFRARED, RAMAN, AND INELASTIC NEUTRON-SCATTERING STUDY

Amorphous minerals are widely distributed in biology, and occur as car bonates, phosphates, and silica. Calcium and magnesium are the major c ations in the phosphate deposits, but in addition, there is usually an organic component, and the minerals are hydrated with up to 20% water . Such deposits are found as intracellular granules in a variety of in vertebrates such as the shore crab Carcinus maenas. These intracellula r granules and synthetic amorphous calcium phosphates and crystalline apatite have been studied by infrared, Raman, and inelastic neutron sc attering to establish the protonation of the phosphates and the struct ure of the water in these deposits. Monetite and newberyite were used as model compounds for comparison. It is concluded that the water occu rs in regions that are only loosely associated with the cations in the se solids.