Proteolytic enzymes

About: Proteolytic enzymes is a research topic. Over the lifetime, 23096 publications have been published within this topic receiving 835544 citations.

Isolation, partial amino acid sequence, and immunohistochemical localization of a brain-specific calcium-binding protein

Abstract: A calcium-binding protein (protein 10) having a molecular mass of 29 kDa and an isoelectric point of 5.3 was purified from guinea pig brain. The amino acid sequence of fragments from proteolytic digestion of protein 10 revealed an 86% sequence identity with a calcium-binding protein (calretinin) found in chicken retina. Polyclonal antibodies against protein 10 revealed a specific distribution of this protein within sensory neurons of auditory, visual, olfactory, nociceptive, and gustatory systems as well as other discrete neuronal circuits in rat and guinea pig brain, whereas no specific label was observed in any of several peripheral tissues examined.

Lens fibre cell differentiation and organelle loss: many paths lead to clarity.

Abstract: The programmed removal of organelles from differentiating lens fibre cells contributes towards lens transparency through formation of an organelle-free zone (OFZ). Disruptions in OFZ formation are accompanied by the persistence of organelles in lens fibre cells and can contribute towards cataract. A great deal of work has gone into elucidating the nature of the mechanisms and signalling pathways involved. It is apparent that multiple, parallel and redundant pathways are involved in this process and that these pathways form interacting networks. Furthermore, it is possible that the pathways can functionally compensate for each other, for example in mouse knockout studies. This makes sense given the importance of lens clarity in an evolutionary context. Apoptosis signalling and proteolytic pathways have been implicated in both lens fibre cell differentiation and organelle loss, including the Bcl-2 and inhibitor of apoptosis families, tumour necrosis factors, p53 and its regulators (such as Mdm2) and proteolytic enzymes, including caspases, cathepsins, calpains and the ubiquitin–proteasome pathway. Ongoing approaches being used to dissect the molecular pathways involved, such as transgenics, lens-specific gene deletion and zebrafish mutants, are discussed here. Finally, some of the remaining unresolved issues and potential areas for future studies are highlighted.

Efficient and specific trypsin digestion of microgram to nanogram quantities of proteins in organic-aqueous solvent systems.

Abstract: Mass spectrometry-based identification of the components of multiprotein complexes often involves solution-phase proteolytic digestion of the complex. The affinity purification of individual protein complexes often yields nanogram to low-microgram amounts of protein, which poses several challenges for enzymatic digestion and protein identification. We tested different solvent systems to optimize trypsin digestions of samples containing limited amounts of protein for subsequent analysis by LC−MS−MS. Data collected from digestion of 10-, 2-, 1-, and 0.2-μg portions of a protein standard mixture indicated that an organic−aqueous solvent system containing 80% acetonitrile consistently provided the most complete digestion, producing more peptide identifications than the other solvent systems tested. For example, a 1-h digestion in 80% acetonitrile yielded over 52% more peptides than the overnight digestion of 1 μg of a protein mixture in purely aqueous buffer. This trend was also observed for peptides from dig...

Bacterial-induced release of inflammatory mediators by bronchial epithelial cells.

Abstract: This review focuses on bacterial induction and release of inflammatory cytokines and adhesion molecules by human bronchial epithelial cells, with special reference to Haemophilus influenzae, a pathogen commonly associated with chronic bronchitis. Studies investigating the mechanisms underlying bacterial colonization of the airways and bacterial-induced chronic airway inflammation have suggested that these are likely to involve localization of bacteria to the site(s) of infection in the respiratory tract and induction of a local airway inflammation resulting in the initiation of epithelial damage. We have hypothesized that the gross airway epithelial damage observed in chronic infective lung disease is an indirect consequence of proteolytic enzymes and toxic oxygen radicals generated by large numbers of neutrophils infiltrating the airways. Furthermore, the infiltration and activation of the neutrophils is a consequence of increased release of proinflammatory mediators from the host respiratory epithelium, induced by bacterial products, such as endotoxin. This hypothesis is based on studies which have demonstrated that the concentrations of circulating cytokines, such as interleukin (IL)-8 and tumour necrosis factor-alpha (TNF-alpha), which have profound effects on neutrophil activity, are increased in endotoxaemia and that airway epithelial cells are a rich source of these cytokines. Support for this hypothesis is provided by studies of cultured human bronchial epithelial cells incubated either in the absence or presence of purified endotoxin preparations from nontypable and type b H. influenzae strains which have demonstrated that these endotoxins lead to significantly increased expression and/or release of proinflammatory mediators, including IL-6, IL-8, TNF-alpha and intercellular adhesion molecule-1 (ICAM-1). Treatment of the cells with steroids can downregulate the expression and/or release of these inflammatory mediators. Additionally, these studies have demonstrated that culture medium collected from endotoxin-treated cultures, 24 h after treatment, significantly increases neutrophil chemotaxis and adhesion to human endothelial cells in vitro.

The Silk Fibroins

Abstract: Publisher Summary Fibroins are regarded as protein filaments produced by certain species belonging to the classes Insecta (insects) and Arachnida (spiders, etc.). In the class Insecta, many species produce long silken filaments to form substantial cocoons in which they pupate. The classic example is the silkworm of commerce Bombyx mori (B. mori), and filaments reeled from the cocoons of this species have been used to make textiles. Other fibroins from the Insecta that have been used commercially include those produced by the larvae of the tussah moths (Antheraea spp.) and by the Anaphe moths (Anaphe spp.). To make the composite thread that constitutes the raw silk of commerce from the Bombyx silk cocoons, the pupating insects are killed by treatment at a high temperature (“stifling”), the sericin is softened with hot water, and the ends of the baves (or cemented pair of filaments) are found and drawn from the cocoons by a process known as “reeling.” In this process, the baves from a number of cocoons are drawn off together to make a composite thread of the required thickness and strength. Tussah silk from the Antheraea spp. is not usually reeled, and it is therefore rare to find it as a continuous filament. The fibroin may be isolated from the raw silk or cocoons in a variety of ways, the best and most common methods of degumming being (1) Extraction of sericin with water, (2) Extraction of sericin with dilute aqueous alkali or with solutions of soaps, (3) Removal of sericin by proteolytic enzymes.