Chemical Structure of the Red Blood Cell

‭Chemical structure of the red blood cell‬ -‭ ‬ ‭There is a low water content: 60% while the hepatocyte contains 75% water and we have a‬ ‭hemoglobin concentration which is at saturation (important) which means that when there are‬ ‭unstable hemoglobins, they tend to precipitate spontaneously. The high protein concentration tends‬ ‭to attract water inside the red blood cell so sodium pumps are needed to force the water out of the‬ ‭red blood cell. cell. There is a fine balance with calcium and magnesium ions because these two‬ ‭ions act on the deformability of the cytoplasmic membrane of the red blood cell and an excess of‬ ‭calcium causes membrane rigidity and very often the red blood cells will no longer be able to pass‬ ‭through the capillaries of small diameters and we will have lysis, intravascular destruction.‬ -‭ ‬ ‭Enzymatic and metabolic capacity:‬‭The red blood cell‬‭no longer contains a nucleus. He‬ ‭has no more capacity to regenerate enzymes and the red blood cell draws its energy mainly from‬ ‭anaerobic glycolysis; it is the Hendon Meyerhof pathway for 90% of the energy of the GR. There is‬ ‭generation of NADPH and ATP. There is a way:the pentose shunt which will participate in the‬ ‭reconstitution of NADPH. These two pathways are regulated at the level of diphosphoglycerate, in‬ ‭fact the 2.3 DPG which will be synthesized from these two routers will exert negative feedback on‬ ‭two steps: that of phosphofructokinase and that of hexokinase. This 2.3 DPG will promote the‬ ‭maintenance of a significant ADP concentration in the cell and NAD or NADP. NADPH and‬ ‭NADH intervene in the fight against meth hemoglobinization:in fact, oxygen has a permanent‬ ‭tendency to oxidize hemoglobin Fe2+ into hemoglobin Fe3+ which is unsuitable for the transport of‬ ‭oxygen. On the other hand ATP is important, the ATPase pumps which transport the cations are in‬ ‭the maintained membrane integrity. The role of 2,3 DPG is to modulate the affinity of hemoglobin‬ ‭for oxygen and it binds to the beta chain of hemoglobin. It maintains hemoglobin in a deoxygenated‬ ‭form.‬ -‭ ‬ ‭The red blood cell membrane:‬‭There is this lipid bilayer‬‭with 60% phospholipids, 30%‬ ‭neutral lipids and 10% glycolipids.‬ ‭In terms of phospholipids, we have an asymmetric distribution between the outer and inner layers:‬ ‭on the outer layer we find 80% of sphingomyelins and lecithins. On the internal leaflet we find all‬ ‭the phosphatidyl serines which are important for the demonstration of the apoptotic process =‬ ‭cellular suicide, in fact during this phenomenon the phosphatidyl serines which are on the internal‬ ‭leaflet are expressed on the external leaflet and this will allow the detection of apoptotic cells within‬ ‭living cells with a protein which will specifically bind to Pser, an example isnexin 5.‬ ‭In the lipid bilayer we find membrane proteins which represent 50% of the weight of the‬ ‭membranes and these are characterized according to their electrophoretic migrations. Membrane‬ ‭proteins are said to be intrinsic when they cross on both sides the lipid bilayer, it is the protein‬ ‭corresponding to band 3 and the glycophorins C. Glycophorins concern the extra membrane side of‬ ‭carbohydrate determinants at the origin of blood groups.‬ ‭Cytoskeleton‬ ‭below‬ ‭the‬ ‭membrane:‬‭deformation‬ ‭capacity‬ ‭of‬ ‭the‬ ‭red‬ ‭blood‬ ‭cell.‬ ‭This‬ -‭ ‬ ‭Cytoskeleton‬ ‭is‬ ‭a‬ ‭fibrous-looking‬ ‭protein‬ ‭network.‬‭In‬‭ME‬‭it‬‭has‬‭a‬‭mesh‬‭appearance‬‭and‬‭filaments‬ ‭and knots are highlighted. It is made up of spectrin and actin filaments.‬ ‭Spectrin is a fibrillar heterodimer: 2 chainz / alpha and beta and there is a cephalic and caudal end.‬ ‭The joints between the different proteins: spectrin, actin interact through protein 4.1 and these are‬ ‭so-called horizontal interactions. On the other hand, interactions with structural proteins like band 3‬ ‭via ankyrin or the interaction between spectrin, actin and glycophorin occurs viaire of protein 4,1,‬ ‭these are vertical interactions.‬