Pathways

The metabolism of proline begins like glutamic acid reacting with acetyl-CoA through a amino-acid acetyltransferase resulting in the release of coenzyme A, hydrogen ion and a N-acetyl-L-glutamate. The latter reacts with an ATP through acetylglutamate kinase resulting in the release of ADP and N-acetylglutamyl-phosphate. The latter then reacts with an NADPH and a Hydrogen ion through a n-acetyl-gamma-glutamyl-phosphate reductase resulting in the release of phosphate, NADP and N-acetyl-L-glutamate 5-semialdehyde. The latter compound reacts with L-glutamate through an acetylornithine transaminase resulting in the release of oxoglutaric acid and N-acetyl-L-ornithine. The latter reacts with Water through a acetylornithine deacetylase resulting in the release of acetate and L-ornithine. Ornithine can also be produced by the acetyl cycle. The acetyl cycle starts with N-acetylglutamic acid being phosphorylated through an acetylglutamate kinase resulting in the release of ADP and N-acetylglutamyl-phosphate. The latter compound reacts with NADPH and a hydrogen ion through a N-acetyl-gamma-glutamyl-phosphate reductase resulting in the release of a phosphate, NADP and N-acetyl-L-glutamic 5-semialdehyde. The latter reacts with L-glutamate through an acetyl ornithine transaminase resulting in the release of oxoglutaric acid and N-acetylornithine. The latter compound reacts with L-glutamic acid resulting in the release of L-ornithine and N-acetylglutamate. The latter compound starts the cycle over again. Ornithine reacts with carbomoyl phosphate through an OTC resulting in the release of phosphate, hydrogen ion and L-citrulline. The latter compound reacts with ATP, and L-aspartate through a argininosuccinate synthase resulting in the release of AMP, diphosphate, hydrogen ion and L-arginino-succinate. The latter compound reacts with argininosuccinate lyase resulting in the release of fumarate and l-arginine. Arginine eacts with water through arginase resulting in the release of urea and l-ornithine. Ornithine reacts with oxoglutaric acid through an ornithine aminotransferase resulting in the release of glutamic acid and l-glutamate 5- semialdehyde react with pyrroline 5 carboxylate dehydrogenase resulting in the release of glutamic acid.Arginine reacts with water through arginase resulting in the release of urea and l-ornithine. Ornithine reacts with oxoglutaric acid through an ornithine aminotransferase resulting in the release of glutamic acid and l-glutamate 5- semialdehyde which can spontaneously react to produce S-pyrroline-5-carboxylate. The latter reacts with pyrroline 5-carboxylate reductase resulting in the release of proline. Proline is degraded by reacting with a proline dehydrogenase resulting in the release of S-1-pyrroline 5-carboxylate. The latter is then spontaneously reacts with water and hydrogen ion resulting in the release of L-glutamate-5-semialdehyde. The latter compoundreacts with NAD and water through a 1-pyrroline-5-carboxylate dehydrogenase resulting in the release of 2 hydrogen ions, NADH and L-glutamic acid.

The biosynthesis of L-proline in E. coli involves L-glutamic acid being phosphorylated through an ATP driven glutamate 5-kinase resulting in a L-glutamic acid 5-phosphate. This compound is then reduced through a NADPH driven gamma glutamyl phosphate reductase resulting in the release of a phosphate, a NADP and a L-glutamic gamma-semialdehyde. L-glutamic gamma-semialdehyde is dehydrated spontaneously, resulting in a release of water,hydrogen ion and 1-Pyrroline-5-carboxylic acid. The latter compound is reduced by an NADPH driven pyrroline-5-carboxylate reductase which is subsequently reduced to L-proline. L-proline works as a repressor of the pyrroline-5-carboxylate reductase enzyme and glutamate 5-kinase. In E. coli, the biosynthesis of L-proline from L-glutamate is governed by three genetic loci namely proB, proA and proC. The first reaction in the pathway is catalyzed by γ-glutamyl kinase, encoded by proB . The second reaction, NADPH-dependent reduction of γ-glutamyl phosphate to glutamate-5-semialdehyde, in the pathway is catalyzed by glutamate-5-semialdehyde dehydrogenase, encoded by proA . These two enzymes aggregate into a multimeric bi-functional enzyme complex known as γ-glutamyl kinase-GP-reductase multienzyme complex. It is believed that the complex formation serves to protect the highly labile glutamyl phosphate from the hostile nucleophilic and aqueous environment found in the cell . The final step in the pathway, the reduction of pyrroline 5-carboxylate to L-proline, is catalyzed by an NADPH-dependent pyrroline-5-carboxylate reductase encoded by proC . Proline is metabolized by being converted back to L-glutamate, which is further degraded to α-ketoglutarate, an intermediate of the TCA cycle. The process by which proline is turned into L-glutamate starts with L-proline interacting with ubiquinone through a bifunctional protein putA resulting in an ubiquinol, a hydrogen ion and a 1-pyrroline-5-carboxylic acid. The latter compound is then hydrated spontaneously resulting in a L-glutamic gamma-semialdehyde. This compound is then processed by interacting with water through an NAD driven bifunctional protein putA resulting in a hydrogen ion, NADH and L-glutamic acid.

Prolinemia Type II is caused by mutation in the pyrroline-5-carboxylate dehydrogenase gene (P5CDH) mitochondrial matrix NAD-dependent dehydrogenase. This dehydrogenase is a catalyst for converting pyrroline-5-carboxylate to glutamate in the proline degradation pathway. An enzyme defect causes accumulation of glycine, hydroxyproline and proline in the urine, ornithine in the serum and proline in plasma. Symptoms include mental retardation, acute and chronic renal failure, and seizures.

Prolinemia Type II is caused by mutation in the pyrroline-5-carboxylate dehydrogenase gene (P5CDH) mitochondrial matrix NAD-dependent dehydrogenase. This dehydrogenase is a catalyst for converting pyrroline-5-carboxylate to glutamate in the proline degradation pathway. An enzyme defect causes accumulation of glycine, hydroxyproline and proline in the urine, ornithine in the serum and proline in plasma. Symptoms include mental retardation, acute and chronic renal failure, and seizures.

Prolinemia Type II is caused by mutation in the pyrroline-5-carboxylate dehydrogenase gene (P5CDH) mitochondrial matrix NAD-dependent dehydrogenase. This dehydrogenase is a catalyst for converting pyrroline-5-carboxylate to glutamate in the proline degradation pathway. An enzyme defect causes accumulation of glycine, hydroxyproline and proline in the urine, ornithine in the serum and proline in plasma. Symptoms include mental retardation, acute and chronic renal failure, and seizures.

Prolinemia Type II is caused by mutation in the pyrroline-5-carboxylate dehydrogenase gene (P5CDH) mitochondrial matrix NAD-dependent dehydrogenase. This dehydrogenase is a catalyst for converting pyrroline-5-carboxylate to glutamate in the proline degradation pathway. An enzyme defect causes accumulation of glycine, hydroxyproline and proline in the urine, ornithine in the serum and proline in plasma. Symptoms include mental retardation, acute and chronic renal failure, and seizures.

Promazine is a weak H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. H1-antihistamines act on H1 receptors in T-cells to inhibit the immune response, in blood vessels to constrict dilated blood vessels, and in smooth muscles of lungs and intestines to relax those muscles. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. H1-antihistamines act on H1 receptors in T-cells to inhibit the immune response, in blood vessels to constrict dilated blood vessels, and in smooth muscles of lungs and intestines to relax those muscles. Allergies causes blood vessel dilation which causes swelling (edema) and fluid leakage. Promazine also inhibits the H1 histamine receptor on bronchiole smooth muscle myocytes. This normally activates the Gq signalling cascade which activates phospholipase C which catalyzes the production of Inositol 1,4,5-trisphosphate (IP3) and Diacylglycerol (DAG). Because of the inhibition, IP3 doesn't activate the release of calcium from the sarcoplasmic reticulum, and DAG doesn't activate the release of calcium into the cytosol of the endothelial cell. This causes a low concentration of calcium in the cytosol, and it, therefore, cannot bind to calmodulin.Calcium bound calmodulin is required for the activation of myosin light chain kinase. This prevents the phosphorylation of myosin light chain 3, causing an accumulation of myosin light chain 3. This causes muscle relaxation, opening up the bronchioles in the lungs, making breathing easier.

Promazine is a weak H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. H1-antihistamines act on H1 receptors in T-cells to inhibit the immune response, in blood vessels to constrict dilated blood vessels, and in smooth muscles of lungs and intestines to relax those muscles. Allergies causes blood vessel dilation which causes swelling (edema) and fluid leakage. Promazine inhibits the H1 histamine receptor on blood vessel endothelial cells. This normally activates the Gq signalling cascade which activates phospholipase C which catalyzes the production of Inositol 1,4,5-trisphosphate (IP3) and Diacylglycerol (DAG). Because of the inhibition, IP3 doesn't activate the release of calcium from the sarcoplasmic reticulum, and DAG doesn't activate the release of calcium into the cytosol of the endothelial cell. This causes a low concentration of calcium in the cytosol, and it, therefore, cannot bind to calmodulin. Calcium bound calmodulin is required for the activation of the calmodulin-binding domain of nitric oxide synthase. The inhibition of nitric oxide synthesis prevents the activation of myosin light chain phosphatase. This causes an accumulation of myosin light chain-phosphate which causes the muscle to contract and the blood vessel to constrict, decreasing the swelling and fluid leakage from the blood vessels caused by allergens.

Promazine is a weak H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. H1-antihistamines act on H1 receptors in T-cells to inhibit the immune response, in blood vessels to constrict dilated blood vessels, and in smooth muscles of lungs and intestines to relax those muscles. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.