Activity of lactoperoxidase when adsorbed on protein layers

Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paperwe have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9mg/m2. A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold

On the adsorption behaviour of saliva and purified salivary proteins at solid/liquid interfaces

Den salivfilm som bildas genom selektiv proteinadsorption på ytor i munhålan har stor profylaktisk betydelse genom sin skyddande funktion och befrämjar därigenom oral hälsa. Några av de adsorberade komponenterna har smörjande funktion (t ex muciner, sura prolinrika proteiner (PRP) och statherin), som är viktig bl a för att förhindra slitage mellan tandytor vid tuggning och hos gnisslare. Vissa salivproteiner upprätthåller kalciumjämvikten på emaljytan (bl a statherin och PRP), vilket är viktigt för att undvika demineralisering av ytan samt för remineralisering av initiala kariesangrepp. Dessutom har bl a PRP, statherin och muciner betydelse för styrningen av mikrofloran på olika sätt, viktigt ur såväl kariologisk som parodontologisk synvinkel. Den initiala salivfilmen är alltså av stor betydelse för den vidare utvecklingen av plack. Det är därför väsentligt att öka förståelsen för de grundläggande processerna vid uppbyggnad av denna samt för att kunna utveckla nya metoder avseende bl a plackkontroll. Denna avhandling omfattar främst studier kring den initiala adsorptionen av salivproteiner såsom MUC5B (mucin), PRP-1, PRP-3 och statherin, samt helsaliv och saliv från de stora spottkörtlarna, till fasta ytor med väldefinierade kemiska ytegenskaper. Den använda tekniken för adsorptionsstudier har framför allt varit ellipsometri, en teknik som möjliggör analys av adsorption in situ och utan att störa systemet. Vi har funnit att det finns ett starkt koncentrationsberoende. Generellt sett har salivproteiner högre bindningsförmåga till hydrofoba ytor. Adsorptionen visar sig vara diffusionskontrollerad under de första minuterna (gäller under dessa experimentella betingelser) för de undersökta salivproteinerna vid låga koncentrationer. På hydrofila ytor, indikerar observationer av adsorptionshastigheten att adsorptionen, av proteiner från undersökta salivsekretioner, sker med hastigheter motsvarande de hos statherin, PRP-3 och PRP-1. På hydrofoba ytor förefaller det emellertid vara komponenter med lägre molekylvikt (snabbare diffusion) som adsorberar initialt. Resultaten indikerar vidare att i saliven från munbottenkörtlarna är andra komponenter än mucinet MUC5B viktiga vid den initiala uppbyggnaden av filmen. I saliven från öronspottkörteln förefaller PRP-1 vara en betydande komponent vid den initiala filmbildningen. Inga statistiska skillnader fanns mellan individerna avseende den adsorberade mängden från de respektive salivsekretionerna.Salivary proteinaceous substances are known to play important roles in the formation of the salivary pellicle. The aim of this study was to investigate some aspects of the interfacial behaviour of selected purified salivary proteins, as well as human saliva secretions, using time resolved in situ ellipsometry. Hydrophobic methylated silica and hydrophilic pure silica were used as test substrates. Experiments were performed in vitro, preferentially in the low concentration range, with samples of fresh human whole resting saliva, parotid resting saliva and submandibular/sublingual resting saliva. The protein fractions investigated were human MUC5B, PRP-1, PRP-3 and statherin, as well as bovine submaxillary mucin (BSM). The results show that the adsorbed amount of material was found to be strongly related to the protein concentration in the range investigated for both pure proteins and secretions. Generally, for both pure proteins and secretions, higher amount of material was adsorbed on hydrophobic surfaces compared to hydrophilic ones. Comparison of the observed adsorption and calculated diffusion rates suggest initial adsorption of low molecular weight proteins/peptides. On hydrophilic surfaces the data indicate adsorption of proteins with diffusion rates corresponding to those of statherin, PRP-3 and PRP-1. MUC5B adsorbs in a later stage from both HWS and the individual secretions, due to its lower diffusion rate. On hydrophobic surfaces, adsorption rates were found to be faster than those calculated for any of the proteins, and thus smaller proteins/peptides appear to be involved. The similar adsorption rates and amounts of PRP-1 and parotid saliva (HPS) on hydrophilic surfaces may suggest that large aPRPs accounts for a substantial portion of the film forming capacity by HPS. Effects of added electrolyte could be explained by general screening effects and specific Ca2+ binding to serine phosphates in aqueous solutions, but were complex in phosphate buffer. Inter-individual differences in adsorbed amounts from HWS, HPS and HSMSLS were not found to be statistically significant

Grundläggande processer vid salivfilmbildning : adsorption från saliv respektive salivproteiner till modellytor

Den 29 april 2002 försvarade legitimerade tandläkaren Liselott Lindh sin avhandling för odontologie doktorsexamen ”On the adsorption behaviour of saliva and purified salivary proteins at solid/liquid interfaces” vid avdelningen för oral protetik, odontologiska fakulteten, Malmö Högskola. Fakultetsopponent var George L. Grobe III, PhD, Director of Material & Surface Science, Bausch & Lomb Rochester, usa. Handledare under avhandlingsarbetet var professor Per-Olof Glantz, avdelningen för oral protetik, odontologiska fakulteten, Malmö Högskola. Syftet med avhandlingen var att öka kunskapen om de grundläggande processerna vid uppbyggnaden av en salivfilm. autorefera

The composition of enamel salivary films is different from the ones formed on dental materials

This study utilized two-dimensional gel electrophoresis (2-DE) to illustrate compositional differences between in vitro salivary conditioning films (denoted pellicles) formed on human enamel as well as on the dental materials titanium and poly methyl methacrylate (PMMA). The salivary pellicles were formed by immersing each surface in individual tubes containing small volumes of freshly collected whole saliva. Saliva remaining in the tubes after 2 hours of pellicle formation was visualized by means of 2-DE and silver staining. The results showed that the protein patterns in 2-DE of the liquid phase of saliva left after exposure to the respective surfaces, regarding proteins below 100 kDa in size, were different depending on the surface used. Several protein groups and/or individual proteins were shown to be distinct for each surface used