Calcium-phosphate mineralization was monitored in systems composed of designed amphiphilic and acidic β-sheet-forming peptides, namely Pro-Phe-(Asp-Phe)5-Pro (PFD-5), Pro-Phe-(Glu-Phe)5-Pro (PFE-5) and Pro-Glu-(Phe-PSer)4-Phe-Glu-Pro (PPS). The three peptides differ solely in terms of their hydrophilic amino acids and therefore, serve as good model for assessment of the effect of the anionic amino acid type on mineralization within the context of the β-sheet structure. Monolayers of the peptides were deposited over simulated body solution (SBF1.5), and the effect of the adsorbing minerals over time was detected by Langmuir isotherm measurements, grazing incidence X-ray diffraction (GIXD) and Brewster angle microscopy (BAM). The results provide insight into mineralized film morphology and peptide lattice behavior during mineralization. The rigidity of the peptide template, along with the type of amino acid side chain, were found to significantly affect mineralization morphology and peptide structure. The results will contribute to a better understanding of calcium-phosphate mineralization in nature and in the context of biomaterials for applications in bone tissue regeneration.