Mechanism of Membrane Damage

Mechanism of membrane damage Theismechanism of membrane attack that results in lysis of the membrane structure a continuation of the classic pathway involving components C5 to C9 as efferent arms. This efferent pathway is also utilized by alternative pathways and other pathways.If the C5 membrane. – C9 pathway is activated, these components will attach to the cell or bacterial Itthat is also possibletothatdothese components can attach to the membrane has nothing withmechanism previous activation. This last event falls into the category of membrane lysis by nearby activating influences. C5C5bhaswith a BMa BM of 180 kd which willhassplit into theto active peptide C5a with 17 kd and of 163 kd. C5b the ability bind C6 andinC7anmolecules toMC5b67. form theAttachment C5b67 complex which attaches to the membrane instant as to the membrane is inhibited by protein S found in blood plasma which molecule is bound asattached SCb67 which cannot attach to the cell membrane. Each MCb67 to the membrane has anthe attachment site for aAtC8-shaped molecule-1-globulin with a membrane. BM of 53 kd forms C5b678 complex. this time, leakage begins in the cell The processmolecule will be accelerated C9 molecule whichcytolytic is a -globulin with a BM ofby72thekdbinding to formofthetheC5b6789 complex. The hole formed intheories the cellthat membrane ofthe8-12 nm is theofplacemembrane lysis occurs. There are 2 explain mechanism membrane damage by the C5b6789 complex: (1) a channel is formed which is walled by the C5b-9 complex protein through the lipid layer. This theory is called the donut theor, (2) the C5b-9socomplex causes reorganization of molecules. lipids and phospholipids inmolecular the membrane that the channel is lined by lipid However, level studies apparently support the first theory.It turns out that components C5b to C9 which are hydrophilic have experienced amphiphilic changes through non-enzymatic mechanisms and arrange in series to acts formlike a membrane attack complex (MAC = membrane attack complex) which an integral protein ofC5b-8 the membrane soand thatact it can tear the integrity of the lipid layer. Once formed, will bind C9 as a catalyst for C9 polymerization as has beenC8,observed in1 tocell18)membrane damage. MAC 660 has kd the– arrangement C5b, C6, C7, C9n(n = so BMMAC ranges from 1850 kd. Ataggregates. low levels ofHowever, C9 versusmembrane C5b-8 MACdamage is not formed but only forms as protein also occurs. In the experiment ittheturned out that C9C5b-8 has thecomplex, ability toit cannot polymerize spontaneously, but without presence of the damage the cell membrane.The spontaneous polymerization of C9 is inbysome aspectsT and similar to thewith the polymerization of perforin, produced cytotoxic NK cells, induction ofofCa++. Perforin polymerwith willCa++can damage the targettumor cell membranes of both types cells. If pure perforin destroy cells or erythrocytes, so C9 requires the presence of C5b-8 before polymerization to damage cell membranes. By by forming channels inandtheGreen cell membrane, ions will enter by the cell followed H2O. Goldberg showed that cells affected complement initiallyofswell, which is out. thenThey followed by rupture ofcomplement the membrane so that the contents the cell come also showed that is capable of causing lytic damage to various cells including: erythrocytes, blood cells, lymphocytes, bacteria and viruses lipoproteins. is a physicochemical phenomenon knowncoated as thewith Donan effect. This swelling There are two possible mechanisms forbydamage toholes cell membranes due to complement effects. If cell damage is caused several in the membrane, then thisshows method showshit"a "double hit" pattern, butwhich if it ismechanism caused by only one hole it a "single pattern. To determine occurred. Mayer conducted experiments with variousresults cells with different amounts of membrane damage. Mayer' s experimental support the single blow theory.Occasionally there is failure of cytolysis by complement. Oneonreason is thought to be the membrane. However, in general failure depends the nature and structurerepair of themembrane membrane,damage. such as the ability of the membrane to immediately