Carboxymethylation of the fibrillar collagen with respect to formation of hydroxyapatite.
Control over crystal growth by acidic matrix macromolecules is an important process in the formation of many mineralized tissues. Highly acidic macromolecules are postulated intermediates in tissue mineralization, because they sequester many calcium ions and occur in high concentrations at mineralizing foci in distantly related organisms. A prerequisite for biomineralization is the ability of cations like calcium to bind to proteins and to result in concert with appropriate anions like phosphates or carbonates in composite materials with bone-like properties. For this mineralization process the proteins have to be modified with respect to acidification. In this study we modified the protein collagen by carboxymethylation using glucuronic acid. Our experiments showed unambigously, that N(epsilon)-carboxymethyllysine is the major product of the in vitro nonenzymatic glycation reaction between glucuronic acid and collagen. We hypothesized that the function of biomimetically carboxymethylated collagen is to increase the local concentration of corresponding ions so that a critical nucleus of ions can be formed, leading to the formation of the mineral. Thus, the self-organization of HAP nanocrystals on and within collagen fibrils was intensified by carboxymethylation.
Ehrlich
Hermann
H
Institute of Bioanalytical Chemistry, TU Dresden, Dresden, 01069 Germany. Hermann.Ehrlich@tu-dresden.de
Hanke
Thomas
T
Simon
Paul
P
Born
René
R
Fischer
Christiane
C
Frolov
Andrej
A
Langrock
Tobias
T
Hoffmann
Ralf
R
Schwarzenbolz
Uwe
U
Henle
Thomas
T
Bazhenov
Vasily V
VV
Worch
Hartmut
H
D000478:Alkylation; D000596:Amino Acids / Q000032:analysis; D032701:Biomimetics; D001894:Borohydrides / Q000737:chemistry; D003094:Collagen / Q000737:chemistry*; D003460:Crystallization; D005947:Glucose / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006038:Glyoxylates / Q000737:chemistry; D006882:Hydroxyapatites / Q000737:chemistry*; D007202:Indicators and Reagents; D008239:Lysine / Q000031:analogs & derivatives / Q000737:chemistry; D008745:Methylation; D020894:Microfibrils; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared
D000596:Amino Acids; D001894:Borohydrides; D006038:Glyoxylates; D006882:Hydroxyapatites; D007202:Indicators and Reagents; D008903:Minerals; C048496:N(6)-carboxymethyllysine; D020723:Glucuronic Acid; D003094:Collagen; C009282:sodium cyanoborohydride; D005947:Glucose; C031150:glyoxylic acid; D008239:Lysine