Sialidase substrates for Sialdiase assays - activity, specificity, quantification and inhibition

Maintaining sidedness and fluidity in cell membrane coatings supported on nano-particulate and planar surfaces

Supported cell membrane coatings meet many requirements set to bioactive nanocarriers and materials, provided sidedness and fluidity of the natural membrane are maintained upon coating. However, the properties of a support-surface responsible for maintaining correct sidedness and fluidity are unknown. Here, we briefly review the properties of natural membranes and membrane-isolation methods, with focus on the asymmetric distribution of functional groups in natural membranes (sidedness) and the ability of molecules to float across a membrane to form functional domains (fluidity). This review concludes that hydrophilic sugar-residues of glycoproteins in the outer-leaflet of cell membranes direct the more hydrophobic inner-leaflet towards a support-surface to create a correctly-sided membrane coating, regardless of electrostatic double-layer interactions. On positively-charged support-surfaces however, strong, electrostatic double-layer attraction of negatively-charged membranes can impede homogeneous coating. In correctly-sided membrane coatings, fluidity is maintained regardless of whether the surface carries a positive or negative charge. However, membranes are frozen on positively-charged, highly-curved, small nanoparticles and localized nanoscopic structures on a support-surface. This leaves an unsupported membrane coating in between nanostructures on planar support-surfaces that is in dual-sided contact with its aqueous environment, yielding enhanced fluidity in membrane coatings on nanostructured, planar support-surfaces as compared with smooth ones.

Evaluation of catalytic activity of human and animal origin viral neuraminidase: Current prospect

With the exception of plants, almost all living organisms synthesize neuraminidase/sialidase. It is a one among the crucial proteins that controls how virulent a microorganism is. An essential enzyme in orthomyxoviruses and paramyxoviruses that destroys receptors is neuraminidase. It plays a number of roles throughout the viral life cycle in addition to one that involves the release of progeny virus particles. This protein is an important target for therapeutic interventions and diagnostic assays. Neuraminidase inhibitors effectively prevent the spread of disease and viral infection. Sensitive, quick, and inexpensive high throughput assays are needed to screen for specific neuraminidase inhibitory chemicals. To characterize the neuraminidase catalytic activity, however, the traditional assays are still the most common in laboratories. This review gives a brief overview of these neuraminidase assays and recent, innovative developments, particularly those involving biosensors.

Molecular approaches for spinal cord injury treatment

Injuries to the spinal cord result in permanent disabilities that limit daily life activities. The main reasons for these poor outcomes are the limited regenerative capacity of central neurons and the inhibitory milieu that is established upon traumatic injuries. Despite decades of research, there is still no efficient treatment for spinal cord injury. Many strategies are tested in preclinical studies that focus on ameliorating the functional outcomes after spinal cord injury. Among these, molecular compounds are currently being used for neurological recovery, with promising results. These molecules target the axon collapsed growth cone, the inhibitory microenvironment, the survival of neurons and glial cells, and the re-establishment of lost connections. In this review we focused on molecules that are being used, either in preclinical or clinical studies, to treat spinal cord injuries, such as drugs, growth and neurotrophic factors, enzymes, and purines. The mechanisms of action of these molecules are discussed, considering traumatic spinal cord injury in rodents and humans.

Ultrasensitive chemiluminescent neuraminidase probe for rapid screening and identification of small-molecules with antiviral activity against influenza A virus in mammalian cells

Influenza A virus is the most virulent influenza subtype and is associated with large-scale global pandemics characterized by high levels of morbidity and mortality. Developing simple and sensitive molecular methods for detecting influenza viruses is critical. Neuraminidase, an exo-glycosidase displayed on the surface of influenza virions, is responsible for the release of the virions and their spread in the infected host. Here, we present a new phenoxy-dioxetane chemiluminescent probe (CLNA) that can directly detect neuraminidase activity. The probe exhibits an effective turn-on response upon reaction with neuraminidase and produces a strong emission signal at 515 nm with an extremely high signal-to-noise ratio. Comparison measurements of our new probe with previously reported analogous neuraminidase optical probes showed superior detection capability in terms of response time and sensitivity. Thus, as far as we know, our probe is the most sensitive neuraminidase probe known to date. The chemiluminescence turn-on response produced by our neuraminidase probe enables rapid screening for small molecules that inhibit viral replication through different mechanisms as validated directly in influenza A-infected mammalian cells using the known inhibitors oseltamivir and amantadine. We expect that our new chemiluminescent neuraminidase probe will prove useful for various applications requiring neuraminidase detection including drug discovery assays against various influenza virus strains in mammalian cells.

A new chemiluminescence neuraminidase probe enables rapid screening of small molecules that inhibit viral replication, directly in influenza A-infected mammalian cells.