Naslov
The Influence of Ionic Strength on Interactions between Myoglobin - Polyelectrolyte in Aqueous Solution

Autori
Roberts, Dorota ; Požar, Josip ; Kovačević, Davor ; Curtis, Robin

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
23rd Conference of the European Colloid and Interface Society : Book of Abstracts / - , 2009

Skup
23rd Conference of the European Colloid and Interface Society

Mjesto i datum
Antalya, Turska, 06.09.2009. - 11.09.2009

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Myoglobin ; Polyelectrolytes ; Ionic Strength

Sažetak
Recent studies on polyelectrolyte multilayers [1 – 3] indicate physical interactions in the multilayer structure can be weakened when exposed to external stimuli. These stimuli can give a controlled material response necessary for applications such as delivery systems for proteins. This study is focused on determining the inter- and intra-molecular interactions between proteins and polyelectrolytes in aqueous solution in the presence of salt at various ionic strength. The main goal is to link the behaviour of protein and polyelectrolyte in solution to suitable conditions for fabrication of polyelectrolyte multilayers through layer-by-layer assembly, where multiple non-covalent bonds across the layers form a well integrated and stable structure. In this study we determine the effect of ionic strength on the interactions between equine heart myoglobin and poly(styrene sulfonate) PSS. The protein-polyelectrolyte interactions are quantified using potentiometric and turbidimetric titration, where characteristic pH values corresponding to water-soluble and water-insoluble protein- polyion complex formation are determined. The pHc1 corresponds to the value of pH where amino groups on protein are able to bind negatively charged groups on PSS, whereas the pHc2 value corresponds to the pH value where myoglobin carboxyl groups are most likely to bind with the PSS groups. At low ionic strength (between 0 and 0.01 mol dm-3) there is a major difference in pHc1 for titration of pure myoglobin (titrated as a reference sample) and myoglobin – PSS system, the difference which decreases with the increasing ionic strength. At the pH values higher than pHc1 equal to 8.2, there is no interaction due to insufficient charge density on the protein to allow binding with polyelectrolyte. It is believed that the onset of water-soluble complex formation occurs in solution at conditions near that pH value. Alternatively, it seems that water-insoluble complex formation takes place at pH value higher than pHc2. From our measurements it could be concluded that the potentiometric titration does not bring the evidence of the onset of water-insoluble complexation and therefore it was essential to use turbidimatric titration to define the critical value of pH where water insoluble complexes are starting to form.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA