Lysing activity

Cytochrome P-450 and cysteine conjugate p-lyse are primarily localized in the proximal tubules, and these enzymes also contribute to the susceptibility of the proximal tubule to toxicant injury. Specifically, widely used industrial solvents such as chloroform produce tubular nephrotoxicity via cytochrome P-450 activation, and haloaUcanes and haloalkenes (e.g. trichloroethylene) are rendered toxic by cysteine conjugate (3-lyse activation [24,24a]. In addition, overdoses of acetaminophen (APAP) cause nephrotoxicity that is characterized by proximal tubular necrosis [25]. APAP undergoes cytochrome P-450-mediated activation to produce a toxic electrophile, N-acetyl-p-benzoquinon-eimine (NAPQI) [25a]. Although NAPQI is extremely reactive, it is detoxified by conjugation with reduced GSH unless NAPQI is formed in excess of the cellular capacity for GSH conjugation. The excess NAPQI is available to bind to critical cellular proteins and to induce oxidative stress, resulting in disruption of cellular homeostasis and tubular injury [26]. 

Many of these peptidolipids have amphiphilic properties. This is illustrated by the protoplast-bursting activity of surfactin (93) or by the strong lysing activity of iturin A (but not iturin C) and bacillomycin L on erythrocytes (166), or the disruption of the outer membrane of Escherichia coli by EM 49 (152). Likewise antibiotics of the iturin group increased the size of small unilamellar vesicles of saturated lecithins (167). Differences in the balance between the hydrophobicity of the hydrocarbon chain and the polarity of the peptide moiety might explain the differences of action of iturin A, mycosubtilin and bacillomycin on Micrococcus luteus cells and protoplasts (168). 

An increasing number of diseases are known to be linked to defects in receptor stmcture, function, or coupling. The defects may He at several locations in the stmcture of the receptor, which may alter its abiHty either to bind dmgs, to be inserted into the membrane, or to couple to effectors (including G-proteins) in the coupling protein or in the presence of autoantibodies, which can proceed to activate, block, or lyse the receptors and its components (96—99). 

Reverse transcriptase (from avian or murine RNA tumour viruses) [9068-38-6] [EC 2.7.7.49]. Purified by solubilising the virus with non-ionic detergent. Lysed virions were adsorbed on DEAE-cellulose or DEAE-Sephadex columns and the enzyme eluted with a salt gradient, then chromatographed on a phosphocellulose column and enzyme activity eluted in a salt gradient. Purified from other viral proteins by affinity chromatography on a pyran-Sepharose column. [Verna Biochim Biophys Acta 473 1 7977 Smith Methods Enzymol 65 560 1980 see commercial catalogues for other transcriptases.]... 

In this method, microbial cells are apparently lysed within the entrapping agent, but they retain the desired enzymatic activity. To prepare an efficient immobilisation, the type and... 

A mechanism of cell-mediated immunity whereby an effector cell of the immune system actively lyses a target cell that has been bound by specific antibodies. The typical ADCC involves activation of natural killer (NR) cells and is dependent on the recognition of... 

There has been considerable discussion regarding the mode of action of the sea cucumber and starfish saponins. Both the triterpene and steroidal glycosides inhibit both Na/K ATPase and Ca/Mg ATPase 06) possibly as a result of their aglycone structures. However, their detergent properties cause membrane disruption which will influence the activity of membrane-bound enzymes such as the ATPases. In investigating the actions of saponins on multilamellar liposomes, it was found that cholesterol serves as the binding site for such saponins and that cholesterol-free lip-somes are not lysed by saponins 107). 

Innate immune response to viral infections is predominately through interferon-alpha, -beta (IFN-a and -P) induction and activation of natural killer (NK) cells. Although viral replication can induce IFN-a and -P expression, macrophages are capable of producing and secreting cytokines which also induce the production of these type I interferons (Falk 2001). Bound IFNa and p to its receptors on NK cells increases its ability to lyse virally-infected cells. 

Mode of action Interferes with bacterial cell wall synthesis during active multiplication, causing cell wall death and resultant bactericidal activity Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins, which in turn inhibit the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls bacteria usually lyse from ongoing autolytic enzyme activity... 

The classical pathway can become activated by immune complexes, bacteria, viruses, and F-XIIa. Binding occurs to the complement C1 q, a part of complement factor 1 (Cl). This initiates a cascade of activations, first of Clr, Cls, then of C4. This C4 activates C2, after which C3 becomes activated. Activated C3 initiates a cascade of activations, which are in common with the alternative pathway and which end up in activated C5-9, a membrane attack complex that lyses the target. 

A lysogenic culture can be treated so that most or all of the cells produce virus and lyse. Such treatment, called induction, usually involves the use of agents such as ultraviolet radiation, nitrogen mustards, or X rays, known to damage DNA and activate the SOS system. However, not all prophages are inducible in some temperate viruses, prophage expression occurs only by natural events. 

Antibodies that, by binding to the cell surface antigen, mark the tumour cell for destruction. NK cells and macrophages express cell surface receptors that bind to the antibody Fc region (Box 13.2). Thus, antibody bound to tumour antigens directs these immune elements directly to tumour surface. Antibodies also activate complement, which is capable of directly lysing tumour cells. 

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