Colorimetric and label free detection of gelatinase positive bacteria and gelatinase activity based on aggregation and dissolution of gold nanoparticles.

A simple and sensitive method was developed for the detection of bacteria gelatinase activity based on their enzymatic hydrolysis effect on the surface plasmon resonance (SPR) of gelatin functionalized gold nanoparticles (Au@gelatin NPs) in bacteria supernatant. Characterization of synthesized NPs showed a very thin gelatin layer on the surface of about 20 nm AuNPs which modified the intrinsic SPR property of AuNPs. The extracted supernatants of applied bacteria were incubated with Au@gelatin NPs.

Quantitative Measurement of the Affinity of Toxic and Nontoxic Misfolded Protein Oligomers for Lipid Bilayers and of its Modulation by Lipid Composition and Trodusquemine.

Many neurodegenerative diseases are associated with the self-assembly of peptides and proteins into fibrillar aggregates. Soluble misfolded oligomers formed during the aggregation process, or released by mature fibrils, play a relevant role in neurodegenerative processes through their interactions with neuronal membranes. However, the determinants of the cytotoxicity of these oligomers are still unclear.

Inhibition potential evaluation of two synthetic bis-indole compounds on amyloid fibrillation: a molecular simulation study.

Protein aggregation is known as the main mechanism of amyloid fibrillation in amyloidosis diseases. Recent studies confirmed that compounds with one or two indole rings have inhibitory potential against amyloid fibrillation. Herein, the interaction of two similar compounds 'bis(indolyl)-2-methyl-phenyl-methene' and 'bis(indolyl)-2-chloro-phenyl-methene' with an amyloid core model was investigated.

Identification of Novel 1,3,5-Triphenylbenzene Derivative Compounds as Inhibitors of Hen Lysozyme Amyloid Fibril Formation.

Deposition of soluble proteins as insoluble amyloid fibrils is associated with a number of pathological states. There is a growing interest in the identification of small molecules that can prevent proteins from undergoing amyloid fibril formation. In the present study, a series of small aromatic compounds with different substitutions of 1,3,5-triphenylbenzene have been synthesized and their possible effects on amyloid fibril formation by hen egg white lysozyme (HEWL), a model protein for amyloid formation, and of their resulting toxicity were examined.

Interaction, cytotoxicity and sustained release assessment of a novel anti-tumor agent using bovine serum albumin nanocarrier.

The interaction ability of bovine serum albumin (BSA) with 2,6-divanillylidenecyclohexanone (DVH) as a stable curcumin derivative was investigated using fluorescence and circular dichroism (CD) spectroscopy techniques under simulative physiological conditions (pH = 7.2). Following the obtained results of binding studies, bovine serum albumin nanoparticles (BSANPs) were synthesized and characterized using Fourier transform infrared spectroscopy (FT-IR), filed emission scanning electron microscopy (FE-SEM), atomic force microscope (AFM) and dynamic light scattering (DLS).

A genetic variant in CDKN2A/2B locus was associated with poor prognosis in patients with esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is among the leading causes of cancer related death. Despite of extensive efforts in identifying valid cancer prognostic biomarkers, only a very small number of markers have been identified. Several genetic variants in the 9p21 region have been identified that are associated with the risk of multiple cancers.

Bis(indolyl)phenylmethane derivatives are effective small molecules for inhibition of amyloid fibril formation by hen lysozyme.

Amyloid or similar protein aggregates are the hallmarks of many disorders, including Alzheimer's, Parkinson's, Huntington's diseases and amyloidoses. The inhibition of the formation of these aberrant species by small molecules is a promising strategy for disease treatment. However, at present, all such diseases lack an appropriate therapeutic approach based on small molecules.

Inhibition of amyloid fibril formation and cytotoxicity by a chemical analog of Curcumin as a stable inhibitor.

Clinical application of curcumin for Alzheimer's disease treatment is severely limited with regard to its poor bioavailability, high rate of metabolism, and instability under neutral condition. In the current study, we designed three compounds in which the diketone moiety of curcumin was replaced by cyclohexanone. In these compounds, the linker length of the molecules was optimal; and substitution of dioxolane for hydroxyl groups on compound 3 should prevent metabolic inactivation.

Effect of Cinnamomum Verum Extract on the Amyloid Formation of Hen Egg-white Lysozyme and Study of its Possible Role in Alzheimer's Disease.

Introduction: Diagnosing and treating diseases associated with amyloid fibers remain a great challenge despite of intensive research carried out. One important approach in the development of therapeutics is the use of herbal extracts which are rich in aromatic small molecules. Cinnamomum verum extract (CE) contains proanthocyanidin and cinnamaldehyde, which have been suggested to be capable of directly inhibiting amyloid fibril formation in vitro.

Oligomeric forms of insulin amyloid aggregation disrupt outgrowth and complexity of neuron-like PC12 cells.

Formation of protein amyloid fibrils consists of a series of intermediates including oligomeric aggregates, proto-fibrillar structures, and finally mature fibrils. Recent studies show higher toxicity for oligomeric and proto-fibrillar intermediates of protein relative to their mature fibrils. Here the kinetic of the insulin amyloid fibrillation was evaluated using a variety of techniques including ThT fluorescence, Congo red absorbance, circular dichroism, and atomic force microscopy (AFM).

Thermal disaggregation of type B yeast hexokinase by indole derivatives: a mechanistic study.

Protein aggregation is a pathological hallmark of several human disorders, and a central problem in biotechnology, occurring during purification, sterilization, shipping and storage of protein structures. The process is a very complex one, characterized with a remarkable polymorphism of aggregates, including soluble amyloid oligomers, amyloid fibrils and amorphous species. While amyloid structure formation has been extensively investigated during the recent years, amorphous aggregation is still not well characterized.

Large proteins have a great tendency to aggregate but a low propensity to form amyloid fibrils.

The assembly of soluble proteins into ordered fibrillar aggregates with cross-β structure is an essential event of many human diseases. The polypeptides undergoing aggregation are generally small in size. To explore if the small size is a primary determinant for the formation of amyloids under pathological conditions we have created two databases of proteins, forming amyloid-related and non-amyloid deposits in human diseases, respectively.

Thermally induced changes in the structure and activity of yeast hexokinase B.

Yeast hexokinase has been poorly characterized in regard with its stability. In the present study, various spectroscopic techniques were employed to investigate thermal stability of the monomeric form of yeast hexokinase B (YHB). The enzyme underwent a conformational transition with a T(m) of about 41.

Thermal aggregation of alpha-chymotrypsin: role of hydrophobic and electrostatic interactions.

We have recently reported that electrostatic interactions may play a critical role in alcohol-induced aggregation of alpha-chymotrypsin (CT). In the present study, we have investigated the heat-induced aggregation of this protein. Thermal aggregation of CT obeyed a characteristic pattern, with a clear lag phase followed by a sharp rise in turbidity.

A study on the two binding sites of hexokinase on brain mitochondria.

Background: Type I hexokinase (HK-I) constitutes the predominant form of the enzyme in the brain, a major portion of which is associated with the outer mitochondrial membrane involving two sets of binding sites. In addition to the glucose-6-phosphate (G6P)-sensitive site (Type A), the enzyme is bound on a second set of sites (Type B) which are, while insensitive to G6P, totally releasable by use of high concentrations of chaotropic salts such as KSCN. Results obtained on release of HK-I from these "sites" suggested the possibility for the existence of distinct populations of the bound enzyme, differing in susceptibility to release by G6P.