35 Amino acids are joined in a protein by the formation of a peptide bond + H 3 N C C N C C O - + H 2 O H R 1 H R 2 O O H + H 3 N C C O - + + H 3 N C C O-H R 1 H R 2 O O Peptide (amide) bond Dipeptide â contains two amino acid residues planar. 36 20 amino acids can form 20 2 or 400 dipeptides.
Hydroxylapatite, also called hydroxyapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca 5 (PO 4) 3 (OH), but is usually written Ca 10 (PO 4) 6 (OH) 2 to denote that the crystal unit cell comprises two entities.Hydroxylapatite is the hydroxyl endmember of the complex apatite group.The OH â ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system.ydroxylapatite is the hydroxyl endmember of the complex apatite group. The OH â ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system.
Apophyllite, potassium-calcium fluoride-silicate mineral that is related structurally to the zeolite family of aluminosilicates. Like the zeolites, it has a high water content, although apophyllite has no aluminum in its chemical composition, which is approximately represented by the formula Ca4KFSi8O20Â·8H2O. In many ways it is more like the micas.