Protease surface activity

UK is a serine protease that activates plasminogen to plasmin. Plasmin dissolves the fibrin in blood clots. The attachment of UK to the islet surface was expected to dissolve blood clots that surrounded the islets in the liver thus, IBMIR could be inhibited in the initial stages. A fibrin plate-based assay was performed to assess the... 

The clotting factors are protein molecules. Activation mostly means proteolysis (cleavage of protein fragments) and, with the exception of fibrin, conversion into protein-hydrolyzing enzymes (proteases). Some activated factors require the presence of phospholipids (PL) and Ca + for their proteolytic activity. Conceivably, Ca + ions cause the adhesion of factor to a phospholipid surface, as depicted in C. Phospholipids are contained in platelet factor 3 (PF3), which is released from ag-Lullmann, Color Atlas of Pharmacology 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 

In many applications several quite different technical criteria must be successfully fulfilled before the product will work , and even then cost and scale-up and commercial criteria must be met. A good example is detergent enzymes where scientists had to discover proteases that would be active and stable under conditions of high pH and temperature and in the presence of oxidising and surface active agents. The same criteria exists for lipases for use in detergents. However, suitable lipases proved rather more difficult to find than the B. subtilis proteases that are used... 

The selective enzyme-catalyzed acylation of carbohydrates is of great interest, as of carbohydrates fatty acid esters of carbohydrates have important applications in detergents, cosmetics, foodstuff, and pharmaceuticals because of their surface-active properties. Monoacylated sugars have been synthesized by lipase-catalyzed transesterifications of activated esters in pyridine and by protease-catalyzed esterifications in DMF. A most remarkable new development... 

Most enzymes of industrial importance like amylase, protease, cellulase, etc. are extracellular. By the addition of surface-active agents, enzyme excretion through cell membranes and consequently the yield of these enzymes can be increased 38). Extracellular enzymes are separated from microbial cells by filtration and, if necessary, in addition by enrichment. Intracellular enzymes are released by disruption of the cells... 

HIV Protease Inhibitor. The bioavailability of ritonavir (Norvir, Abbott), an HIV protease inhibitor, was enhanced by formulation as a solid dispersion in a mixture of surface active carrier, such as Gelucire 50/13, polysorbate 80, and polyoxyl-35 castor oil. 

Once sensitivity has been established, that is, once hapten-specific IgE-producing B cells have been formed, exposure to even small amounts of hapten can induce a cascade of events that lead to immediate reactions, such as anaphylaxis (210). Briefly, preformed IgE antibodies to drug determinants recognize the hapten-carrier complex and fix to the surface of mast cells or basophils, triggering the release of a series of mediators, such as histamine, neutral proteases, biologically active arachidonic acid products, and cytokines. This ultimately leads to a clinical spectrum that ranges from a mUd local reaction to anaphylactic shock. 

To evaluate the biological applicability of this design, Smith and Hirschmann have developed HIV-1 protease inhibitors based on the polypyrrolinone scaffold. Previous studies have shown that many binding interactions are conserved in the HIV-1 protease/inhibitor complex formation [36]. /3-Strand peptide inhibitors, such as 5 and JG-365 (Ac-Ser-Leu-Asn-Phe-Hea-Pro-Ile-Val-OMe, Hea - hydroxylamine [CH(OH)CH2N]), bind in an active site on the HIV-1 protease surface with their side chains inserting into hydrophobic pockets (Fig. 4.3-4). 

Oxidants injure tumor cells by acting synergistically with protease and/or by inactivating plasma antiproteases to allow proteases to operate. After their LFA-1- or Mac-1-dependent recognition of the target tumor or EC surface, activated neutrophils release HOCl, resulting in tumor cell lysis, microvessel injury and matrix degradation [43]. 

Enzymatic techniques can be used to endow proteins with surface-active functionality. An enzymatic technique that has shown promise in enhancing surface properties of proteins is a modified version of the classical plastein reaction. The plastein reaction is known to be a protease-catalyzed reverse process in which a peptide-peptide condensation reaction [11,12] proceeds through the peptidyl-enzyme intermediate formation [13]. It is essentially a two-step process enzymatic hydrolysis of a protein and plastein formation from the hydrolysate peptides. A novel one-step process was developed as a modified type of the plastein reaction by Yamashita et al. [14,15], which... 

Sulfonated surfactants are also powerful protease deactivators [67]. The presence of the sulfonate group on benzene makes sodium dodecyl benzene sulfonate, also called LAS (linear alkylbenzene sulfonate), more surface active than SDS. As a result, LAS is an even more efficient denaturant than SDS [27] and alcohol ethoxy sulfates [32]. For instance, in a 0.02% LAS solution, the activity of the protease from Bacillus stearothermophilus is reduced to 20% of its value in water [68]. Likewise, the subtilisin saturation by surfactants at pH 7.4 has been reported to occur at surfactant to enzyme ratios (w/w) of 6.3 (SDS) and 3.2 (LAS) [69]. 

Factor VII. This is a vitamin K-dependent serine protease that functions in the extrinsic coagulation pathway and catalyzes the activation of Factors IX and X. Factor VII is present constitutively in the surface membrane of pericytes and fibroblasts in the adventitia of blood vessels, vascular endothehum, and monocytes. It is a single-chain glycoprotein of approximately 50,000 daltons. 

Protein G. This vitamin K-dependent glycoproteia serine protease zymogen is produced ia the Hver. It is an anticoagulant with species specificity (19—21). Proteia C is activated to Proteia by thrombomodulin, a proteia that resides on the surface of endothefial cells, plus thrombin ia the presence of calcium. In its active form, Proteia selectively iaactivates, by proteolytic degradation. Factors V, Va, VIII, and Villa. In this reaction the efficiency of Proteia is enhanced by complex formation with free Proteia S. la additioa, Proteia activates tissue plasminogen activator, which... 

The use of a bioadhesive, polymeric dosage form for sustained dehvery raises questions about swallowing or aspirating the device. The surface area is small, and patient comfort should be addressed by designing a small (less than 2 cm ), thin (less than 0.1 mm (4 mil) thick) device that conforms to the mucosal surface. The buccal route may prove useful for peptide or protein dehvery because of the absence of protease activity in the sahva. However, the epithelium is relatively tight, based on its electrophysiological properties. An average conductance in the dog is 1 mS/cm (57) as compared to conductances of about 27 and 10 mS/cm in the small intestine and nasal mucosa, respectively (58,59) these may be classified as leaky epitheha. 

The elucidation of the X-ray structure of chymotrypsin (Ref. 1) and in a later stage of subtilisin (Ref. 2) revealed an active site with three crucial groups (Fig. 7.1)-the active serine, a neighboring histidine, and a buried aspartic acid. These three residues are frequently called the catalytic triad, and are designated here as Aspc Hisc Serc (where c indicates a catalytic residue). The identification of the location of the active-site groups and intense biochemical studies led to several mechanistic proposals for the action of serine proteases (see, for example, Refs. 1 and 2). However, it appears that without some way of translating the structural information to reaction-potential surfaces it is hard to discriminate between different alternative mechanisms. Thus it is instructive to use the procedure introduced in previous chapters and to examine the feasibility of different... 

Fig. 2.2 (A) Structure of full-length NS3 including the N-terminal protease domain (bottom) and C-terminal helicase domain (top). The NS4A peptide (purple) is covalently attached to the N-terminus of NS3 (see text). Within the protease domain the N- and C-terminal -barrels are at the right and left, respectively. The zinc atom is visible at the bottom left. [98]. (B) Surface view of the NS3 protease domain showing compound (1) bound at the relatively shallow active site (See also Fig. 2.6) [42].

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