Proteolytic enzymes

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

Blood cells and endothelial barrier function.

Abstract: The barrier properties of endothelial cells are critical for the maintenance of water and protein balance between the intravascular and extravascular compartments. An impairment of endothelial barrier function has been implicated in the genesis and/or progression of a variety of pathological conditions, including pulmonary edema, ischemic stroke, neurodegenerative disorders, angioedema, sepsis and cancer. The altered barrier function in these conditions is often linked to the release of soluble mediators from resident cells (e.g., mast cells, macrophages) and/or recruited blood cells. The interaction of the mediators with receptors expressed on the surface of endothelial cells diminishes barrier function either by altering the expression of adhesive proteins in the inter-endothelial junctions, by altering the organization of the cytoskeleton, or both. Reactive oxygen species (ROS), proteolytic enzymes (e.g., matrix metalloproteinase, elastase), oncostatin M, and VEGF are part of a long list of mediators that have been implicated in endothelial barrier failure. In this review, we address the role of blood borne cells, including, neutrophils, lymphocytes, monocytes, and platelets, in the regulation of endothelial barrier function in health and disease. Attention is also devoted to new targets for therapeutic intervention in disease states with morbidity and mortality related to endothelial barrier dysfunction.

The Nature of the Collagen Synthesized by Cultured Human Fibroblasts

Abstract: The hydroxyproline-containing proteins (hyproproteins) synthesized by cultured human fibroblasts have been partially characterized. The hyproprotein extracted from the cell layer was found to be similar to the collagen extracted from skin in the ratio of hydroxyproline to proline, chain composition, solubility, and resistance to proteolytic digestion. The hyproproteins isolated from the medium were different. About 20% of the peptide-bound hydroxyproline was found in randomly coiled chains. The α2 chains were present in considerable excess over the α1 chains, suggesting that the α2 chain may be synthesized in quantities greater than required to form a collagen molecule with a chain composition (α1)2α2. The remaining medium hyproprotein appeared to be an unusual form of native collagen which, unlike typical native collagen, was soluble under physiological conditions. This hyproprotein did not yield α chains when denatured and contained material that had a molecular weight greater than α chains. A similar size distribution was observed in the protein synthesized in the presence of β-aminopropionitrile, a specific inhibitor of collagen cross-linking. After treatment with pepsin, typical α1 and α2 chains were obtained from the protein in a 2:1 ratio. Since the medium protein is soluble and has properties different from the typical collagen molecule, it may represent a modified form that functions in the transport of collagen from the cell to the fiber.

Natural Prevalence of Hepatitis C Virus Variants with Decreased Sensitivity to NS3·4A Protease Inhibitors in Treatment-Naive Subjects

Abstract: BACKGROUND The prevalence and clinical implications of naturally occurring variants that are resistant to hepatitis C virus (HCV) protease inhibitors in treatment-naive patients has not been reported. We report here the prevalence of such variants and their effect on clinical response. METHODS Population sequence analysis of the NS3.4A protease was conducted in 570 treatment-naive subjects. RESULTS Most subjects (98%) had wild-type virus. The remaining subjects had the following variants present in significant proportions (100%): V36M, 0.9%; R155K, 0.7%; V170A, 0.2%; and R109K, 0.2%. The V36M, R109K, and V170A substitutions confer low-level resistance ( 70-fold) to BILN 2061 and ITMN-191. Five subjects with the V36M or R109K variant were treated with 8-24 weeks of TVR and peginterferon-alpha2a (P) with or without ribavirin (R). Four achieved a sustained viral response, and 1 was lost to follow-up. In subjects with the R155K variant, TVR/PR provided greater antiviral activity than PR alone; however, the antiviral response was lower than that observed in subjects with wild-type virus. CONCLUSION High levels of naturally occurring protease inhibitor-resistant variants were uncommon (<1% each) in HCV treatment-naive patients. TVR/PR efficiently inhibited V36M and R109K variants and contributed partial antiviral activity against the R155K variant. As new HCV agents are evaluated in clinical trials, it will be important to monitor the effect of baseline variants on sensitivity.

Non-antigenic collagen and articles of manufacture

Abstract: Collagen, available from domestic animals, is freed of noncollagen proteins, glycosaminoglycans and lipids by enzymatic treatment with a proteolytic enzyme to yield a product which is soluble in dilute acidic aqueous solutions (collagen in solution--CIS). The naturally occurring collagen is modified by removal of certain terminal peptide chains, which are described as telopeptides. The modified collagen, so derived, is described as atelopeptide collagen. Native collagen is immunogenic, while atelopeptide collagen is nonimmunogenic or possessed of a negligibly low level of immunogenicity. The collagen in solution is then treated according to a specific regimen under conditions whereby the collagen slowly separates from solution while exposed to mild shear forces. This procedure results in the formation of a fibrous precipitate composed of regularly ordered fibers of collagen possessed of a ropelike structure. These resulting aggregates are referred to as native fibrous micropolymers (NFM). Once the regimen or procedure is completed, and the fiber mass has been formed, the fibrous micropolymers may be freed of salt, taken up in a different solution or modified. For example, cross-links may then be introduced to stabilize the fibers. The products find wide use as packing, membranes, fibers, bags, supports, integuments, and are especially suitable for biologic implantation or application.