Synthesis and physicochemical characterization of zinc-lactoferrin complexes

Abstract

One trend of the modern world is the search for new biologically active substances based on renewable resources. Milk proteins can be a solution for such purposes as they have been known for a long time as compounds that can be used for the manufacturing of multiple food and non-food products. Thus, the goal of the work was to investigate the parameters of Znbovine lactoferrin (bLTF) interactions, which enables the synthesis of Zn-rich protein complexes. Zinc-bLTF complexes can be used as food additives or wound-healing agents. Methodology of the study included bLTF characterization by sodium dodecyl sulfate-PAGE, MALDI-TOF, and MALDI-TOF/TOF mass spectrometry as well Zn-bLTF interactions by attenuated total reflection-Fourier-transform infrared, Raman spectroscopy, scanning and transmission microscopy, and zeta potential measurements. The obtained results revealed that the factors that affect Zn-bLTF interactions most significantly were found to be pH and ionic strength of the solution and, in particular, the concentration of Zn 2+ . These findings imply that these factors should be considered when aiming at the synthesis of Zn-bLTF metallocomplexes.

Synthesis, Physicochemical Characterization, and Antibacterial Performance of Silver—Lactoferrin Complexes

“…Additionally, even though the Ag + binding process was performed in acidic conditions, it did not cause significant loss of iron. The Fe 3+ content in the complex was 1.31 ± 0.13 mg/g, which is almost the same as in native bLTF (1.45 ± 0.06 mg/g, protein-to-metal ratio ≈1:2 [22]). The results show the surface character of Ag + binding and high correlation of the estimated silver content in the complex with derived q m from the Langmuir model.…”

“…The signal at ≈82. Other signals (from A to D) were assigned to protein impurities, which mainly come from the protein fragmentation during storage or production [22]. After silver immobilization onto bLTF, the decrease in all signals' intensity can be observed.…”

“…However, silver ions (Ag + ) of this precursor exist only in acidic conditions, while the increased pH above 6 causes the formation of insoluble silver oxide (Ag 2 O) [21]. In turn, it was shown that the interaction of metals with proteins occurs more effectively at higher pH [9,22]. The respective nanocomposites are also more stable in basic pH.…”

The Study of Protein–Cyclitol Interactions

“…The band appears at 1294 cm −1 for the BSA control, which is responsible for the α-helix structure, while the peaks at 1272 and 1238 cm −1 can be assigned to the β-turn and β-sheet, respectively. New bands appear at 1312, 1304, and 1302 cm −1 (α-helix) and at 1246 and 1242 cm −1 (β-sheet) in the presence of cyclitols [ 66 , 67 ].…”

“…Weak signals were observed at 1122 cm −1 (stretching C–O vibrations of aspartic and glutamic acids), 1088 cm −1 (stretching C–N vibrations coupled with bending C–H vibrations of histidine), 1062 cm −1 (stretching C–O vibrations of threonine), 1000 cm −1 (symmetric stretching C–C ring vibrations of phenylalanine), and 972 cm −1 (stretching C–O vibrations of serine) for the protein sample [ 59 , 67 , 68 ]. This region was overlapped by new intensive bands at 1112 cm −1 , 1110 cm −1 , and 1044 cm −1 (assigned to stretching C–O and O–H vibrations) from BSA–cyclitol complexes [ 69 ].…”