Proteolytic enzymes

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

What is gluten

Abstract: Gluten is the main storage protein of wheat grains. Gluten is a complex mixture of hundreds of related but distinct proteins, mainly gliadin and glutenin. Similar storage proteins exist as secalin in rye, hordein in barley, and avenins in oats and are collectively referred to as “gluten.” The objective was to discuss the biochemical and functional properties of the gluten proteins, including structure, sources, and dietary intakes. Literature was reviewed from food science and nutrition journals. The gluten protein networks vary because of different components and sizes, and variability caused by genotype, growing conditions, and technological processes. The structures and interactions of this matrix contribute to the unique properties of gluten. The resulting functions are essential to determining the dough quality of bread and other baked products. Gluten is heat stable and has the capacity to act as a binding and extending agent and is commonly used as an additive in processed foods for improved texture, moisture retention, and flavor. Gliadin contains peptide sequences that are highly resistant to gastric, pancreatic, and intestinal proteolytic digestion in the gastrointestinal tract. The average daily gluten intake in a Western diet is thought to be 5–20 g/day and has been implicated in several disorders. Gluten containing grains (wheat, rye, barley, and oats) are important staple foods. Gluten is among the most complex protein networks and plays a key role in determining the rheological dough properties.

Endothelial cell killing by neutrophils. Synergistic interaction of oxygen products and proteases.

Abstract: Killing of rat pulmonary artery endothelial cells by activated polymorphonuclear leukocytes (PMNs), as measured at 4 hours, is catalase sensitive, iron dependent, and unaffected by addition of protease inhibitors. If the time course for exposure of endothelial cells to activated PMNs is extended to 18 hours, progressive injury occurs. Endothelial cell injury resulting at 18 hours is partially inhibited by catalase and partially inhibited by soybean trypsin inhibitor. Together, these two inhibitors function synergistically to protect the cells from injury. Exposure of endothelial cells to reagent H2O2 and purified proteolytic enzymes (trypsin, chymotrypsin, elastase, and cathepsin G) mimics the effects of activated PMNs: H2O2 alone is cytotoxic with maximal killing achieved by 4 hours; proteolytic enzymes produce cytotoxicity only at high concentrations and only after prolonged incubation (longer than 8 hours); and, in combination, H2O2 and proteolytic enzymes act synergistically. These data provide compelling evidence that PMN-mediated injury of endothelial cells involves interaction between oxygen products and proteases.

A proteolytic enzyme produced by group a streptococci with special reference to its effect on the type-specific m antigen

Abstract: 1. Group A streptococci sometimes produce in broth culture an extracellular proteolytic enzyme. 2. Under suitable cultural conditions the enzyme has been demonstrated in representative cultures of most of the Griffith types. Its production by a given strain may be suppressed by serial passage through mice and the variant so produced has been found to maintain this change in character on subculture in artificial media. 3. Under certain conditions, the enzyme attacks the type-specific M antigens of all the group A streptococci so far tested, with the exception of that of type 28. The enzyme exhibits its maximal activity at 37 degrees C.: Extracts made from enzyme-producing cultures which have been grown at this temperature lack the M antigen; enzyme-producing strains may sometimes be induced to yield M substance in extracts by culturing the streptococci at 22 degrees C. Cultures which, when grown at 37 degrees C. yield M substance in extracts, do not produce the enzyme. 4. Human and rabbit fibrin are attacked and streptococcal fibrinolysin is also inactivated by the enzyme. Other susceptible substrates include casein, milk, gelatin, and benzoyl-l-arginineamide but not l-leucylglycylglycine. 5. The general properties of the enzyme resemble those of papain and some of the cathepsins: It is active under the reducing conditions produced in broth cultures by the presence of living bacteria; it is also activated by substances which reduce disulfide to sulfhydryl groups, e.g. potassium cyanide, cysteine, glutathione, and thioglycollic acid, but it is not activated by ascorbic acid. The enzyme is inactivated by iodoacetic acid and also by normal rabbit or mouse serum.

Rapid and sustained improvement in bone and cartilage turnover markers with the anti-interleukin-6 receptor inhibitor tocilizumab plus methotrexate in rheumatoid arthritis patients with an inadequate response to methotrexate: results from a substudy of the multicenter double-blind, placebo-controlled trial of tocilizumab in inadequate responders to methotrexate alone.

Abstract: Objective To investigate the effects of tocilizumab (TCZ) added to a stable dosage of methotrexate (MTX) on biochemical markers of bone and cartilage metabolism in patients in the multicenter double-blind, placebo-controlled OPTION (Tocilizumab Pivotal Trial in Methotrexate Inadequate Responders) study who have moderate-to-severe rheumatoid arthritis (RA) and an inadequate response to MTX. Methods Included in this study were 416 of the 623 patients with active RA enrolled in the OPTION study. Patients were randomized to receive TCZ (4 mg/kg or 8 mg/kg) or placebo intravenously every 4 weeks, with MTX continued at the stable prestudy doses (10–25 mg for 20 weeks, with a final followup at week 24). Serum biochemical markers of bone formation (osteocalcin, N-terminal propeptide of type I collagen [PINP]), bone resorption (C-terminal crosslinking telopeptide of type I collagen [CTX-I] and C-terminal crosslinking telopeptide of type I collagen generated by matrix metalloproteinases [ICTP]), cartilage metabolism (N-terminal propeptide of type IIA collagen [PIIANP]), collagen helical peptide [HELIX-II]), and matrix metalloproteinase 3 (MMP-3) were measured at baseline and at weeks 4, 16, and 24. Results TCZ induced marked dose-dependent reductions in PIIANP, HELIX-II, and MMP-3 levels at week 4 that were maintained until week 24, an effect associated with increased levels of bone formation markers that were significant as compared with placebo only for PINP and only at 4 weeks (P < 0.01 for both TCZ doses). TCZ induced significant decreases in the bone degradation markers CTX-I and ICTP, providing initial evidence of a beneficial effect on bone turnover. TCZ-treated patients who met the American College of Rheumatology 50% improvement criteria (achieved an ACR50 response) or achieved clinical remission (as determined by a Disease Activity Score in 28 joints <2.6) at week 24 had greater reductions in ICTP, HELIX-II, and MMP-3 levels as compared with ACR50 nonresponders. Conclusion TCZ combined with MTX reduces systemic bone resorption, cartilage turnover, and proteolytic enzyme MMP-3 levels, which provides evidence of a limitation of joint damage and possible beneficial effects on skeletal structure in patients with established moderate-to-severe RA.