A linear neutral repetitive peptide, (Leu‐Gln‐Pro)n (n = 1‐100), an analog of the Ca2+ ion‐binding domain of the matrix protein, amelogenin, has been synthesized. The polypeptide is mostly unordered in trifluoroethanol (TFE) at 25°C and its circular dichroism (CD) spectrum resembles that of the protein itself. In TFE the CD spectrum of (Leu‐Gln‐Pro)n reveals that the polypeptide interacts strongly with divalent cations Mg2+, Ca2+, Sr2+, and Ba2+ accompanied by conformational rearrangement from a random to a more‐ordered one. In the presence of Li+, Na+ and K+ ions no such conformational change has been observed. The CD curves of the complexes suggest the presence of type I β‐turns and reinforce the hypothesis that the region Gln112‐Leu138 in amelogenin is the Ca2+‐binding domain. In the solid state, powder X‐ray diffraction suggests that the polymeric (LQP)n may exist as isolated “rigid rods”.