Random and sequential copolypeptides containing O-phospho-L-threonine and L-aspartic acid; roles in CaCO3 biomineralization.
The present study describes the synthesis of novel polypeptides containing O-phospho-L-threonine [Thr(PO(3)H(2))] and L-aspartic acid. Random copolypeptides copoly[Thr(PO(3)H(2))(X)Asp(Y)] (X:Y = 25:75, 50:50, 75:25), were conventionally prepared by copolymerization of Thr(PO(3)Ph(2)) N-carboxyanhydride (NCA) and Asp(OBzl) NCA followed by deprotection of the phenyl and benzyl groups by catalytic hydrogenolysis over PtO(2). Polycondensation of the protected peptide p-nitrophenyl esters [Thr(PO(3)Ph(2))](Z)-Asp(OBzl)-ONp and subsequent deprotection yielded the sequential polypeptides poly[Thr(PO(3)H(2))(Z)-Asp] (Z = 1-4). By using the synthetic polypeptides, their effects on the growth of CaCO(3) crystals were examined. In the poly[Thr(PO(3)H(2))(Z)-Asp]/CaCO(3) systems, brushlike calcite and spherical vaterite were formed, with the former being found at [Ca(2+)]/[Res] ratios of > or =180, > or =140, > or =120, and > or =100 for Z = 1, 2, 3, and 4, respectively. These results indicate that an increase of Thr(PO(3)H(2)) residues in the repetitive unit induces the characteristic brushlike calcite, a fact indicating that Thr(PO(3)H(2)) residues can modify the CaCO(3) crystal morphology.
Institute of High Polymer Research, Faculty of Textile Science and Technology, Shinshu University, Tokida 3-15-1, Ueda 386-8567, Japan.
Shinya
S
Hayashi
Kousaku
K
Ohkawa
Hiroyuki
H
Yamamoto
D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization; D008855:Microscopy, Electron, Scanning; D008968:Molecular Conformation; D009904:Optical Rotation; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*; D013912:Threonine / Q000737:chemistry*; D014783:Viscosity
D010455:Peptides; D013912:Threonine; D001224:Aspartic Acid; D002119:Calcium Carbonate