Diabetes is a complex metabolic disorder that can cause changes in the composition and function of saliva. Therefore, it seems that the study of saliva composition in patients with diabetes will help in its diagnosis, prognosis, and complications. The present study aimed to compare the saliva’s lysozyme and glycosylated lysozyme levels of patients with type 2 diabetes (T2D) in comparison with healthy individuals. Lysozyme and glycosylated lysozyme levels of salivary samples were measured using ELISA method. The results of this study showed that salivary lysozyme levels were lower in T2D patients. Meanwhile, the salivary glycosylated lysozyme levels were higher in T2D patients compared to control (p≤ 0.001). Salivary lysozyme levels in patients with long-term diabetes (more than three years) were significantly lower than those of T2D patients having the disease for three years. Also, salivary glycosylated lysozyme levels were significantly higher in patients with long-term diabetes (more than three years) than in patients with short-term diabetes (less than three years). In conclusion, the results of this study demonstrated that the salivary lysozyme level in patients with T2D was lower than in healthy individuals. Also, the salivary glycosylated lysozyme level of the T2D patients was higher than healthy individuals. Increased duration of T2D affliction also appears to be associated with increased salivary glycosylated lysozyme levels. Moreover, the increase of salivary glycosylated lysozyme was greater in patients with T2D than in healthy individuals. These findings indicate the important role of salivary glycosylated lysozymes in diagnosing and predicting the complications of diabetic patients.

Amyloidogenic proteins undergo an alternative folding pathway under stressful conditions leading to formation of fibril products, presenting cross β-sheet structure which is the hallmark of many neurodegenerative diseases. The current work demonstrates the effectiveness of phloridzin small molecule on the inhibition of hen egg white lysozyme (HEWL) amyloid formation. The inhibitory effects were analyzed by thioflavin T-induced fluorescence, circular dichroism, and atomic force microscopy. This report demonstrated that naturally occurring small molecules may serve a function that is typically done by protein chaperones, and it provides a hint for designing inhibitors against amyloid formation products associated with neurodegenerative diseases. This report showed that phloridzin considerably hindered nucleation, and therefore, fibrillation of lysozyme in a dose-dependent manner.

Background: Lysozyme is a part of human and animal noncellular immunity. The regulation of its activity by hormones is poorly studied. The aim of this study was to test the in vitro activity of lysozyme in the presence of catecholamines, natriuretic hormones, and E2. Methods: Hormones were incubated with lysozyme, and the activity of lysozome was further determined using a test culture of Micrococcus luteus in the early exponential growth stage. The activity of lysozyme was assessed based on the rate of change in the OD of the test culture. Molecular docking was performed using SwissDock server (http: //www. swissdock. ch/docking), and molecular structures were further analyzed and visualized in the UCSF Chimera 1. 15rc software. Results: According to the results, EPN and NE increased lysozyme activity up to 180% compared to the hormone-free enzyme. Changing the pH of the medium from 6. 3 to 5. 5, increased the lysozyme activity in the presence of E2 up to 150-200 %. The results also showed that exposure to hormones could modify lysozyme activity, and this effect depends on the temperature and pH value. The molecular docking revealed a decrease in the activation energy of the active site of enzyme during the interaction of catecholamines with the amino acid residues, asp52 and glu35 of the active site. Conclusion: Our findings demonstrate an additional mechanism for the involvement of lysozyme in humoral regulation of nonspecific immunity with respect to human pathogenic microflora and bacterial skin commensals by direct modulation of its activity using human hormones.

Misfolding and aggregation of various proteins and peptides is associated with a growing list of diseases, including neurodegenerative disorders such as Alzheimer's, Parkinson's, and Huntington's diseases and peripheral disorders such as systemic amyloidosis and type-II diabetes. Consequently, inhibition of protein aggregation and amyloid fibril formation is viewed as one possible method to prevent the progression of these devastating disorders. A promising strategy for preventing of these diseases is to identify compounds that inhibit amyloid fibril formation. Using ThT fluorescence assay, transition electron microscopy and circular dichroism, here we examined the effects of the naturally occurring polyphenol resveratrol on the fibrillogenesis and cytotoxicity of Hen Egg White Lysozyme (HEWL) fibrils. Our results demonstrate that resveratrol effectively inhibit amyloid fibril formation in a concentration dependent manner. In addition, exciting fibrils of HEWL were disaggregated by resveratrol, as confirmed by ThT fluorescence assay. Furthermore, protective effects of resveratrol against cytotoxicity induced by HEWL fibrils were confirmed using cell viability MTT assay. Although the mechanisms by which resveratrol inhibit fibril formation and destabilize preformed HEWL fibrils are still unclear, we suggest that antioxidative properties as well as anti-amyloidogenic activities of resveratrol underlie its protective effects. It is concluded that naturally occurring polyphenols could serve as scaffold for the design of more efficient inhibitors for amyloid fibril formation in vivo.

Effects of b-cyclodextrin, bCD, on refolding of lysozyme was investigated at pH 12 employing isothermal titration calorimetry (ITC) at 300K in 30mM Tris buffer solution. bCD was employed as an anti-aggregation agent and the heats obtained for lysozyme+bCD interactions are reported and analyzed in terms of the extended solvation model. It was indicated that there are two sets of identical and non-cooperative sites for bCD. Enthalpic force in the first binding sites is more important than entropic one, indicating that electrostatic interaction plays an important role in the interaction of lysozyme with bCD. The interaction in the second binding sites is stronger and both enthalpy and entropy driven but hydrophobic interaction has more important than electrostatic force. These results suggest that the effects of bCD on lysozyme refolding are attributed to its ability to suppress aggregation of the protein.

Application of lysozyme as a natural antimicrobial or preservative agent in food and pharmaceutical industry is well known. The antimicrobial effects of lysozyme can be expanded by conjugation with carbohydrates via Maillard reaction, however this natural reaction is a time consuming process. So in this study a new method microwave heating, was applied to Accelerate the Maillard reaction. Lysozyme was mixed with dextran and heated by microwave irradiation. The glycation extent was determined by SDS-PAGE electrophoresis, cation-exchange chromatography and sugar analysis. SDS-page pattern show that with increasing heating time a high molecular weight conjugates were appeared and maximum glycosylation was occurred after 4 minutes heating. The elution profiles (chromatograms) of the lysozyme–dextran conjugates compared the natural lysozyme showed that the conjugated peak shifted towards the higher molecular weight fraction and overlapped with the non conjugated proteins, indicated that lysozyme was covalently bound to dextran. These results suggest that Maillard reaction rate can be increase using microwave heating.

Neurodegenerative disease such as Alzheimer, Parkinson and so many related diseases are associated with a form of protein conformational change known as amyloid fibrils product. It was showed that fibrils and protofibrils intermediates are cytotoxic, therefore numerous reports have been attempt to inhibit fibrillation process as a therapeutic methods. Peptides, surfactants and aromatic small molecules have been applied as fibrillation inhibitors. In this report, we examined the interaction of the two natural small molecules (fisetin and diadzin) with hen egg white lysozyme (HEWL) for inhibiting the fibril formation products with different kinds of methods such as fluorescence, dynamic light scattering, transmission electron microscopy and circular dichroism. The aim of this study was based on bringing information into possible mechanism of interaction of natural small molecules with amyloied formation products. This report showed that fisetin and diadzinconsiderably hindered nucleation, and therefore, fibrillation of lysozyme in a dose-dependent manner.

Gold nanoparticles are promising materials for biomedical applications because of the attractive optical properties such as the absorption and scattering of light at resonant wavelength. Due to the fruitful applications of gold nanoparticles (GNPs), they are appropriate for a variety of biological studies. One of the most important applications of nanoparticles is protein carriers, in which transport of therapeutically relevant protein is done to in vivo or in vitro targets. Protein folding and properties of probable intermediates during the folding of proteins had been investigated in several studies. The molten globule state, a main intermediate of protein folding, has native-like secondary but perturbation of tertiary structure. Consequently, the influence of gold nanoparticles concentration on a model protein was studied by far-and near-UV circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), intrinsic fluorescence emission spectroscopy and 8-Anilino-1naphthalenesulfonic acid binding. The results indicated that the interactions between gold nanoparticles and lysozyme lead to the formation of molten globule-like state.

Protein aggregation is a serious problem for both biotechnology and cell biology. Diseases such as prion misfolding, Alzheimer’s, and other amyloidosis are phenomena for which protein aggregation in our living cells is of considerable relevance. Human lysozyme has been shown to form amyloid fibrils in individuals suffering from nonneuropathic systemic amyloidosis, all of which have point mutations in the lysozyme gene. In this study, we investigated effect of small additives on the thermal aggregation of lysozyme. The main finding of this work is that multiple amine groups, spermine and spermidine, play pivotal roles in preventing the thermal aggregation of lysozyme. Our results showed that effect of spermine is more than spermidine.

The interaction between nano-SiO2 and lysozyme was investigated by the method of UV-Visible detection and fluorescence spectroscopic techniques. The thermal denaturation of lysozyme has been investigated in the presence and absence ofnano-SiO2 over the temperature range (293-373) K in different buffers and pH values, using temperature scanning spectroscopy. The presence ofnano-SiO2 caused the destabilization of lysozyme resulting in a decrease in the temperature of unfolding with an increase innano-SiO2 concentration.