University of Zagreb. Faculty of Science. Department of Chemistry.
Abstract
Međudjelovanje malih organskih molekula i/ili makromolekula s anorganskim kristalima važno je za razumijevanje procesa taloženja u prirodi. Između različitih biominerala, kalcijevi fosfati privlače posebnu pažnju zbog uloge u biološkoj i patološkoj mineralizaciji i industrijskim procesima. U novije vrijeme, istraživanja utjecaja aditiva na nastajanje kalcijevih fosfata uglavnom su usmjerena na proteine. Iako su opći principi tih međudjelovanja poznati, uloga pojedinih aminokiselina nije još do kraja razjašnjena.
Cilj ovoga rada je istraživanje utjecaja aminokiselina koje pri fiziološkim uvjetima imaju bočne ogranke različitih naboja: fenilalanina (nenabijen), asparaginske kiseline (negativno nabijen), asparagina (polaran, nenabijen), serina (polaran, nenabijen) i lizina (pozitivno nabijen).
Napredovanje taloženja kalcijevih fosfata praćeno je potenciometrijski, što je omogućilo određivanje vremena indukcije. Nastali talog analiziran je infracrvenom spektroskopijom s Fourierovom transformacijom, pretražnom elektronskom mikroskopijom, transmisijskom elektronskom mikroskopijom i difrakcijom rendgenskih zraka na praškastom uzorku.
Dobiveni rezultati ukazali su da utjecaj aminokiselina na svojstva kalcijevih fosfata ovisi o naboju njihovog bočnog ogranka.Mechanisms of interaction between soluble small organic molecules and/or macromolecules with inorganic crystals are of major importance for crystallization processes in nature. Among different biogenic crystals, calcium phosphates attract attention due to their role in the normal and pathological mineralization, as well as in industrial processes. Recent investigations of the influence of additives on the formation of calcium phosphates are mostly focused on protein and their building blocks, amino acids. Althought general principles of these interactions are known, the role of specific amino acids is still unclear.
The aim of this research was to investigate the influence of amino acids with side chains of different properties at physiological conditions: phenylalanine (uncharged, hydrophobic), aspartic acid (negatively charged), arginine (uncharged, polar), serine (uncharged, polar) and lysine (positively charged).
The progress of precipitation was followed potentiometrically, which enabled determination of induction time. Fourier transform infrared spectroscopy, powder x - ray diffraction, scanning and transmission electron microscopy were used for characterization of the precipitates.
Given results show the influence of amino acids on properties of calcium phosphates. The obtain resultes show that the infuence of amino acids on calcium phosphates’ properties dependes on the charge of their side chain
