Secondary structure and limited three-dimensional structure of bovine amelogenin.
Secondary structural features of bovine amelogenin, a hydrophobic protein of developing enamel implicated in ename mineralization, are derived using 2D NMR spectroscopy in solution and molecular mechanics-dynamics studies. A beta-turn: beta-sheet model with some "unordered" segments was previously proposed from circular dichroism, Fourier-transform infrared and Raman spectroscopy augmented by Chou-Fasman predictive algorithm. The proposed structure contains a repetitive beta-turn segment, "beta-spiral" between Gln112 and Leu138 residues containing a (Pro, Leu, Gln) rich segment. The beta-spiral structure offers a probable site for interaction of Ca++ ions. Assignment of proton resonances using 2D COSY spectroscopy is presently in progress. Preliminary 2D NOESY spectra have revealed the presence of Tyr residues (TRAP segment) on the surface of amelogenin molecule and clusters of cross peaks reminiscent of beta-turns and sheets which are consistent with the primary structure and proposed secondary structures of amelogenin. The channel-like beta-spiral structure embedded in amelogenin provides a novel mechanism for trapping of Ca++ ions and their passage for a hydrophobic protein sparse in Ser(P) and charged amino acid residues.
Renugopalakrishnan
V
V
Harvard Medical School, Children's Hospital, Boston, MA.
Prabhakaran
M
M
Huang
S G
SG
Balasubramaniam
A
A
Strawich
E
E
Glimcher
M J
MJ
D053523:Amelogenin; D000818:Animals; D002417:Cattle; D003746:Dental Enamel Proteins / Q000648:ultrastructure*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011487:Protein Conformation
D053523:Amelogenin; D003746:Dental Enamel Proteins