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Dahlin S, Angstriim J, Linde A: Dentin phosphoprotein sequence mot{ (.\' and molecular modeling: cot!/i>nnational adaptations to mineral crystals. Eur J Oral Sci 1998; 106 (suppl / ): 239 248. fl Eur J Oral Sci. 1998 Molecular modelin g has been used to investigate structural fea tures of oligopeptides derived from possible primary structure motifs in highly phosphorylated dentin phosphoprotein ( PP-I-1 ). the predominant noncollagenous protein in dentin . It contains a large number of aspartate (Asp) and phosphoserine ( Pse) residues. the latter proposedly crucial for the PP-I-1 function as a mineral nucleator. In this work, computer f1tting and subsequent structural adaptation of model peptides. built exclusively from Asp and P~e. to the known crystal structures of hydroxyapatite (HAP) and octacalcium phosphate (0 P) were performed. The results show that, when considering conformational energies of fitted single strand oligo-peptides, either crystal will se rve. Within a narrow range. fitting to 0 P was slightly favored, except for oligo(Pse Pse Asp Asp). which showed a slightly better fit to HAP. Energy differences between crystal-adapted and non-adapted freely minimized peptides showed that oligo( Pse Asp) docked to either HAP or OCP were the energetically most favored adaptations. Fitting of minimized triple anti-parallel f)-strands of oligo(Pse Asp) or oligo(Pse Pse Asp). motifs found in published sequences of rat. mouse. and bovine PP-H. revealed that a (001) crystal face of HAP. but most likely not OCP. may be formed by these f)-sheet models . The former motif is more advantageous in thi s respect.

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A method for reconstituting the blue copper protein stellacyanin with the stable copper isotopes 63Cu and 65Cu is reported. Small differences in the e.p.r. spectra of the two isotopic forms of stellacyanin have been used to monitor the electron self-exchange reaction of stellacyanin by rapid-freeze e.p.r. methods. The self-exchange rate constant (k11) for stellacyanin has been determined as 1.2 X 10(5) M-1 X S-1 at 20 degrees C. This value is in close agreement with values obtained from less-direct methods.