Antiproteinases

Deficiency of -Antiproteinase (tti-Antitrypsin) Is Associated With Emphysema One Type of Liver Disease... 

Table 52-12. Proteinases of neutrophils and antiproteinases of plasma and tissues. ...

The proteinases of neutrophils can digest many tissue proteins normally, this is kept in check by a battery of antiproteinases. However, this defense mechanism can be overcome in certain circumstances, resulting in extensive tissue damage. 

AP ai-antiproteinase also known as ai-antitrypsin and ai-proteinase inhibitor... 

Proteinases and antiproteinases are part of the normal protective and repair mechanisms in the lungs. The imbalance of proteinase-antiproteinase activity in COPD is a result of either increased production or activity of destructive proteinases or inactivation or reduced production of protective antiproteinases. AAT (an antiproteinase) inhibits trypsin, elastase, and several other proteolytic enzymes. Deficiency of AAT results in unopposed proteinase activity, which promotes destruction of alveolar walls and lung parenchyma, leading to emphysema. 

Antiproteinase A substance that inhibits the enzymatic activity of a proteinase. 

In this method, ai-antiproteinase inhibits the hydrolytic enzyme elastase, and the remaining elastase activity is measured by monitoring increases in absorbance at410 nm. Martmez-Tome and others (2001) used a method based on this reaction to measure the antioxidant activity of broccoli amino acids and of Mediterranean spices. 

Aslam, A., Newman, T. L. and Misbah, S. A. Audit of the clinical usefulness of a rapid qualitative ELISA screen for antimyeloperoxidase and antiproteinase 3 antibodies in the assessment of patients with suspected vasculitis. /. Clin. Pathol. 56 775-777, 2003. 

The acute-phase response is characterised by the enhanced (two- to threefold) synthesis of a number of proteins, such as antiproteinases, complement components, fibrinogen and ceruloplasmin, which are normally synthesised at fairly low rates. The rate of synthesis of some proteins is enhanced 100-1000-fold - for example, C-reactive protein, a-macroglobulin and acid-1-glycoprotein. Thus, serum levels of these proteins serve as indicators of disease. 

C5a is inactivated by the myeloperoxidase-H202 system, which oxidises a methionine residue (Met 70) on the molecule group A streptococcal endo-proteinases also abolish chemotactic activity of C5a and related compounds. Neutrophil lysosomal enzymes (e.g. elastase and cathepsin G) also destroy C5a chemotactic activity, but as these proteases are inhibited by the serum antiproteinases, a -antiproteinase and a2-macroglobulin, the physiological role of neutrophilic proteases in the inactivation of C5a is questionable. Two chemotactic factor inactivators have been found in human serum an a-globulin that specifically and irreversibly inactivates C5-derived chemotactic factors, and a / -globulin that inactivates bacterial chemotactic factors. These activities are heat labile (destroyed by treatment at 56 °C for 30 min) and are distinct from those attributable to anaphylatoxin inactivator. An apparently specific inhibitor of C5-derived chemotactic activity has also been described in human synovial fluid and peritoneal fluid. This factor (molecular mass of 40 kDa) is heat stable and acts directly on C5a. 

Schmidtchen A (2000) Degradation of antiproteinases, complement and fibronectin in chronic leg ulcers. Acta Derm Venereol 80(3) 179-184... 

Kirkovsky VV, Antiperovich OF, Valueva TA, Moin VM, Lobacheva GA, Berezkina OG (1994) Biospecific haemosorbents based on proteinase inhibitor 111. Biospecific antiproteinase... 

S. Brenton, M. Ayad, and E.D. Janus. 1997. The proteinase-antiproteinase theory of emphysema a speculative analysis of recent advances into the pathogenesis of emphysema. Respirology 2 91-95. 

Hypochlorite, released from inflammatory cells, can induce the inactivation of a i-antiproteinase by oxidising a crucial methionine residue at the active centre of the enzyme. Inactivation of the a j-proteinase inhibitor may allow proteases... 

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