The red blood cell membrane is composed ..

Human erythrocytes lack cellular organelles, DNA and RNA, and thus also many metabolic pathways such as oxidative phosphorylation, TCA cycle, β-oxidation, and protein synthesis.

31/12/2017 · The Erythrocyte Kathleen Finnegan ..

If RBC-derived ATP is an important determinant of endogenous NO synthesis in the ..

Function and Synthesis of Hemoglobin - Interactive …

Synthesis of purine ribonucleotides
IMP is synthesized from ribose 5-phosphate. There are 11 reactions in the formation of IMP. IMP is converted to GMP and AMP with the help of ATP and GTP respectively. Nucleoside monophosphates are converted to nucleoside diphosphates by base specific monophosphate kinases. Purine nucleotide synthesis is regulated by feedback inhibitor – AMP, GMP and IMP. An important regulatory factor is the availability of PRPP. Salvage pathway for purines is observed in RBC and the brain. Free purines are salvaged by APRTase and HGPRTase enzymes

Synthesis of pyrimidine ribonucleotides
Pyrimidine ring is synthesized as free pyrimidine and then it is incorporated into the nucleotide. 6 reactions are involved in the synthesis of UMP. UDP and UTP are synthesized from UMP with the help of ATP. CTP is formed by adding an amino group from glutamine. Pyrimidine can also be salvaged using PRPP. In orotic aciduria, excretion of large amount of orotic acid is observed. It results from the deficiency of either orotate phospho ribosyl transferase or OMP decarboxylase.

Function and Synthesis of Hemoglobin

Synthesis of purine ribonucleotides
IMP is synthesized from ribose 5-phosphate. There are 11 reactions in the formation of IMP. IMP is converted to GMP and AMP with the help of ATP and GTP respectively. Nucleoside monophosphates are converted to nucleoside diphosphates by base specific monophosphate kinases. Purine nucleotide synthesis is regulated by feedback inhibitor – AMP, GMP and IMP. An important regulatory factor is the availability of PRPP. Salvage pathway for purines is observed in RBC and the brain. Free purines are salvaged by APRTase and HGPRTase enzymes

Synthesis of pyrimidine ribonucleotides
Pyrimidine ring is synthesized as free pyrimidine and then it is incorporated into the nucleotide. 6 reactions are involved in the synthesis of UMP. UDP and UTP are synthesized from UMP with the help of ATP. CTP is formed by adding an amino group from glutamine. Pyrimidine can also be salvaged using PRPP. In orotic aciduria, excretion of large amount of orotic acid is observed. It results from the deficiency of either orotate phospho ribosyl transferase or OMP decarboxylase.

The resulting current drives ATP synthesis from ADP and inorganic phosphate

Chapter 3 The Red Blood Cell: Structure and Function

Mitochondrial Oxidative Phosphorylation/Electron Transport: The TCA cycle accomplishes what glycolysis didn't, that is the cleavage of all C-C bonds in glucose (in the form of pyruvate and acetyl-CoA, and the complete oxidation of all C atoms to CO2. Yet two problem remains. The pool of oxidizing molecules, NAD+ and FAD get converted to their reduced forms, NADH and FADH2. Unless NAD+ and FAD are regenerated, as was the case in anaerobic conditions when pyruvate gets converted to lacate, the pathway would again come to a grinding halt. In addition, not much ATP is made in the cycle (in the form of a related molecule GTP). Both these problems are resolved as the resulting NADH and FADH2 formed are reoxidized by mitochondrial membrane enzyme complexes which pass electrons from the oxidized NADH and FADH2 to increasingly potent oxidizing agents until they are accepted by the powerful oxidant O2,which is converted reduced to water. The net oxidation of NADH and FADH2 by dioxygen is greatly exergonic, and the energy released by the process drives the synthesis of ATP from ADP and Pi by an mitochondrial enzyme complex, the F0F1ATPase.

higher RBC ATP/ADP content may control ..

CATBOLISM: Catabolic reactions involve the breakdown of carbohydrates, lipids, proteins, and nucleic acids to produce smaller molecules and biological energy in the form of heat or small thermodynamically reactive molecules like ATP whose further degradation can drive endergonic process such as biosynthesis. Our whole world is reliant on the oxidation of organic hydrocarbons to water and carbon dioxide to produce energy (at the expense of releasing a potent greenhouse gas, CO2). In the biological world, reduced molecules like fatty acids and partially oxidized molecules such as glucose polymers (glycogen, starch), as well as simple sugars, can be partially or fully oxidized to ultimately produce CO2 as well. Energy released from oxidative reactions is used to produce molecules like ATP as well as heat. Oxidative pathways include glycolysis, the tricarboxylic acid cycle (aka Kreb's cycle) and mitochondrial oxidative phosphorylation/electron transport. To fully oxidize carbon in glucose and fatty acids to carbon dioxide requires splitting C-C bonds and the availability of series of oxidizing agents that can perform controlled, step-wise oxidation reactions, analogous to the sequential oxidation of methane, CH4 to methanol (CH3OH), formaldehyde (CH2O) and carbon dixoxide.

REALITY #14: WARBURG'S PROOF: THE DATA POINTS …

AB - A role for nitric oxide (NO) produced during the reduction of nitrite by deoxygenated red blood cells (RBCs) in regulating vascular dilation has been proposed. It has not, however, been satisfactorily explained how this NO is released from the RBC without first reacting with the large pools of oxyhemoglobin and deoxyhemoglobin in the cell. In this study, we have delineated a mechanism for nitrite-induced RBC vasodilation that does not require that NO be released from the cell. Instead, we show that nitrite enhances the ATP release from RBCs, which is known to produce vasodilation by several different methods including the interaction with purinergic receptors on the endothelium that stimulate the synthesis of NO by endothelial NO synthase. This mechanism was established in vivo by measuring the decrease in blood pressure when injecting nitrite-reacted RBCs into rats. The observed decrease in blood pressure was not observed if endothelial NO synthase was inhibited by N ω-nitro-L-arginine methyl ester (L-NAME) or when any released ATP was degraded by apyrase. The nitrite-enhanced ATP release was shown to involve an increased binding of nitrite-modified hemoglobin to the RBC membrane that displaces glycolytic enzymes from the membrane, resulting in the formation of a pool of ATP that is released from the RBC. These results thus provide a new mechanism to explain nitrite-induced vasodilation.