Self-assembly Of Protein Subunits Research Articles

Protein-based nanomaterials: a new tool for targeted drug delivery.

Protein nanomaterials are well-defined, hollow protein nanoparticles comprised of virus capsids, virus-like particles, ferritin, heat shock proteins, chaperonins and many more. Protein-based nanomaterialsare formed by the self-assembly of protein subunits and have numerous desired properties as drug-delivery vehicles, including being optimally sized for endocytosis, nontoxic, biocompatible, biodegradable and functionalized at three separate interfaces (external, internal and intersubunit). As a result, protein nanomaterials have been intensively investigated as functional entities in bionanotechnology, including drug delivery, nanoreactors and templates for organic and inorganic nanomaterials. Several variables influence efficient administration, particularly active targeting, cellular uptake, the kinetics of the release and systemic elimination. This review examines the wide range of medicines, loading/release processes, targeted therapies and treatment effectiveness.

Micelle formation and crystallization as paradigms for virus assembly

Self-assembly processes of crystallization, micelle formation and virus assembly, by their creation of geometric order from disordered components, represent first-order phase transitions that arise through the formation of partially ordered intermediates. The self-assembly of protein subunits into the geometric shells of polyhedral viruses may proceed through formation of reverse micelles, and be driven by condensation of encapsidated nucleic acid complexed with the amino terminal polypeptides of the coat proteins. Restructuring of subunits on the fluid, micellar surface, analogous to processes on the surfaces of growing crystals, then leads to symmetrical, icosahedral capsids. Such a pathway for viral assembly is attractive because it utilizes only physical properties inherent to the system, and it shares many characteristics that we know to be associated with those two other preeminent examples of self-assembly, micelles and crystals.

Tobacco Mosaic Virus with Emphasis on the Events Within the Host Cell Following Infection

Publisher Summary This chapter presents the structure and properties (physical, chemical, and biological) of the tobacco mosaic virus (TMV). TMV is a rod-shaped particle. The virus particle is built up of a helical array of subunits set about the long axis of the particle. The protein subunits of the TMV are packed together in such a way as to leave space for the RNA between them. Thus, the RNA is embedded tightly between protein subunits. The self assembly of protein subunits to form a helical structure similar to that of TMV can take place with or without RNA. However, the association of RNA contributes to the stability of the completed particle. The chapter also discusses the events that take place within the host cell following infection with TMV. TMV is composed of 95% protein and 5% RNA. This RNA is released into the host cell to initiate infection. The parental viral RNA may remain bound to the nuclear structures in the host cell and does not enter the pool of newly synthesized viral RNA (progeny viral RNA), which is rapidly assembled into the progeny TMV. The parental RNA localized in the nucleus performs dual functions: one is that of a messenger directing the synthesis of the needed enzymes and the other is that of a template in the synthesis of its complementary strand.

Self-assembly of protein subunits from alfalfa mosaic virus

The self-assembly of alfalfa mosaic virus (AMV) protein subunits containing various amounts of residual RNA has been investigated. AMV protein, containing about 0.8% of residual RNA, formed capsids corresponding in appearance to small virus particles and sedimenting at 38 S. Best yields were observed between pH 7 and 8.0, in a buffer containing 0.1 M NaCl. With protein containing about 1.5% to 2% residual RNA, both small and double-shelled spheres occurred, particularly at pH 8.0 in 0.1 M NaCl; this protein also formed double-bacilliform particles. At a level of residual RNA of approximately 3%, the proportion of double-shelled to single-shelled partic les was high and varied with temperature and pH. Residual RNA extracted from contaminated AMV protein had a very low molecular weight. When 3% of this residual RNA was added to AMV protein, double shells occurred. When 3% of unfractioned AMV RNA was added to protein contaminated by 0.8% of residual RNA, no double-shelled spheres or double-bacilliform particles occurred; heavy components corresponding to those of AMV were formed only when the unfractioned AMV RNA: protein ratio reached 1:10. Sonicated Hemophilus influenzae DNA (3 × 10 6 daltons) gave rise to long flexuous particles, the number of which decreased as soon as extracted residual AMV RNA was added to the mixture.

Self-assembly of protein subunits from bacteriophage fr

Self-assembly of protein subunits from bacteriophage fr