Sulphur Containing Amino Acids PDF

# Sulphur Containing Amino Acids ## Co-A * Co-A * Pantothenic acid. * Taurine: Conjugation of bile acids. ## Glutathione * Tripeptide, Pseudopeptide/Atypical peptide * 3 amino acids : Glutamic acid + Cysteine + Glycine * AKA Gamma glutamyl cysteinyl glycine (GSH) ## Functions of Glutathione 1....

# Sulphur Containing Amino Acids ## Co-A * Co-A * Pantothenic acid. * Taurine: Conjugation of bile acids. ## Glutathione * Tripeptide, Pseudopeptide/Atypical peptide * 3 amino acids : Glutamic acid + Cysteine + Glycine * AKA Gamma glutamyl cysteinyl glycine (GSH) ## Functions of Glutathione 1. Amino acid transport: * meister's cycle/Gamma glutamyl cycle. * used in intestine, brain, Kidney. * utilizes ATP. 2. Free radical scavenging: * H₂O₂ + Reduced glutathione -> NADP⁺ + Glutathione peroxidase * H₂O₂ + Oxidized glutathione -> NADPH + H⁺ + Glutathione reductase * HMP shunt 3. Conjugation / Phase II reactions: * used in xenobiotics (Preservatives, drugs). 4. Coenzyme role: * Cis-trans isomerase -> Fumaryl acetoacetate. * maleyl acetoacetate ## Sulphur Containing Amino Acids * methyl Bid * Reabsorption of cysteine in Kidney * Deficiency of B₆/Folic acid/B₁₂ → ↑ Homocysteine → CAD/CVA. * Cystinuria ### Folate trap: * THFA * Trapped -> N methyl THFA * THFA starvation/ * Functional deficiency of THFA * Folic acid deficiency ## Classical Homocysteinuria * Biochemical defect: * ↑ Homocysteine in blood * ↑ Homocysteine in urine * ↓↓ Cysteine synthesis. * Clinical features: * Asymptomatic (Initially) * Skeletal deformities * Arachnodactyly: Elongated fingers * mental Retardation. * Developmental delay. * Tall stature * High arched palate * Genu varum. * Pectus Carinatum * Pectus excavatum ## Sulphur Containing Amino Acids * Knee - Genu varum. * Knee - Genu valgum. * Pes cavus/planus. * Scoliosis. ### Dislocation of lens * Ectopia lentis: * Downward & medial * Note: * D/d: marfan syndrome * No mental retardation. * Superotemporal dislocation of lens. ### Lab diagnosis: * Cyanide nitroprusside test : magenta color → Positive test * Enzyme studies. * Genetic mutation studies. ### Treatment: * Cysteine supplementation. * Methionine (Substrate) restriction. ## Sulphur Containing Amino Acids * THFA * NS methyl THFA * Homocysteine * Methyl Transferase/ Homocysteine * Methionine Synthase * S-adenosyl homocysteine * Cystathionine + B₆ synthase * Homoserine + Cysteine * S-adenosyl methionine (Principle methyl donor) * CH₃ * S-adenosyl homocysteine * methionine adenosyl transferase * S-adenosyl methionine ### Metabolic pathway: * THFA * methyl B₁₂ * NS methyl THFA * Homocysteine * methyl Transferase/ Homocysteine * methionine Synthase * serine * S-adenosyl homocysteine * Cystathionine + B₆ synthase ## Sulphur Containing Amino Acids * Betaine supplementation * Trimethyl glycine → methyl donor → Homocysteine → methionine. ## Proteins and Amino Acids ## Classic vs Non-classic homocysteinuria: | Defect | Classic | Non-classic | |---|---|---| | Cysteine | CBS | B₆, B₁₂ MTHFR| | ↓ | ↓ | Normal | ## Cystinuria * Defect : Dibasic amino acid transporter in kidney. * Reabsorb dibasic aminoacid: COLA * Cystine * Ornithine * Lysine * Arginine * Excreted * Part of Garrod's tetrad ## Cystinosis * Lysosomal storage disorder. ### Defect: * H* driven lysosomal cystine transporter. * CTNS gene → Cystinuria 342ce29f02c7 ### Clinical manifestations: * Liver failure. * Kidney failure. * Comeal opacity. * Bone marrow suppression ## Specialised products from cysteine: * Betamercaptoethanolamine (Component of Co-A). * Co-A. * Pantothenic acid. * Taurine: Conjugation of bile acids. ## Glutathione ## Cysteine & Methionine | | Cysteine | Methionine | |--------------------|----------|------------| | Structure | H NH-C-COOH | H NH-C-COOH | | | ↓ ↓ ↓ | ↓ ↓ ↓ | | | SH | CH₃ | | | Sulfhydryl/Thiol/ | Thioether linkage | | | Thioalcohol group | | | Type of amino acid | Glucogenic | Glucogenic | | | Polar aminoacid | Non-polar (Terminal group is CH₃) | | | Non-essential (Can be synthesized from methionine) | Essential | ## HOMOCYSTEINE * S-adenosyl methionine (SAM): * Homocysteine + methyl group = methionine * Adenosine - Thioether linkage : Covalent bond ## Sulpur Containing Amino Acids * Pes cavus * Thromboembolism: * Risk factor for atherosclerosis ## Dislocation of lens * Ectopia lentis: * Downward & medial * Note: * D/d: marfan syndrome * No mental retardation. * Superotemporal dislocation of lens. ## Lab Diagnosis * Cyanide nitroprusside test : magenta color → Positive test. * Enzyme studies * Genetic mutation studies. ## Treatment * Cysteine supplementation * Methionine (Substrate) restriction.