Скачать с ютуб Chapter - 3 || Metabolism Of Sulphur Containing Amino Acids (Part-9) - Hindi в хорошем качестве

Chapter - 3 || Metabolism Of Sulphur Containing Amino Acids (Part-9) - Hindi

📌 𝐅𝐨𝐥𝐥𝐨𝐰 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦:-   / drgbhanuprakash   📌𝗝𝗼𝗶𝗻 𝗢𝘂𝗿 𝗧𝗲𝗹𝗲𝗴𝗿𝗮𝗺 𝗖𝗵𝗮𝗻𝗻𝗲𝗹 𝗛𝗲𝗿𝗲:- https://t.me/bhanuprakashdr 📌𝗦𝘂𝗯𝘀𝗰𝗿𝗶𝗯𝗲 𝗧𝗼 𝗠𝘆 𝗠𝗮𝗶𝗹𝗶𝗻𝗴 𝗟𝗶𝘀𝘁:- https://linktr.ee/DrGBhanuprakash *Metabolism of Sulphur-Containing Amino Acids* *Introduction* Sulphur-containing amino acids play crucial roles in protein synthesis, antioxidant defense, and metabolic regulation within the human body. The metabolism of these amino acids, primarily cysteine and methionine, involves intricate biochemical pathways that are essential for various physiological processes. *1. Methionine Metabolism* - **Methionine Ingestion**: Dietary methionine is the primary source of methionine in the body, obtained from protein-rich foods. - **Absorption and Transport**: Methionine is absorbed in the small intestine and transported via the bloodstream to tissues. - **Conversion to S-adenosylmethionine (SAM)**: - Methionine undergoes adenosylation to form SAM, catalyzed by methionine adenosyltransferase. - SAM serves as a methyl donor in numerous methylation reactions, including DNA methylation, neurotransmitter synthesis, and histone modification. - **Transmethylation Reactions**: - SAM donates its methyl group to various acceptor molecules, forming S-adenosylhomocysteine (SAH). - SAH is subsequently hydrolyzed to homocysteine and adenosine. - **Remethylation Pathway**: - Homocysteine can be remethylated to form methionine through the action of methionine synthase, which requires methylcobalamin (Vitamin B12) as a cofactor. - Folate and Vitamin B12 are essential for the remethylation process. - **Transsulfuration Pathway**: - Alternatively, homocysteine can enter the transsulfuration pathway. - In this pathway, homocysteine combines with serine to form cystathionine, catalyzed by cystathionine β-synthase. - Cystathionine is then converted to cysteine, a process that requires Vitamin B6 (pyridoxal phosphate) as a cofactor. *2. Cysteine Metabolism* - **Cysteine Synthesis**: - Cysteine can be synthesized de novo from serine via the transsulfuration pathway. - Alternatively, cysteine can be obtained from dietary sources. - **Cysteine Incorporation into Proteins**: - Cysteine is utilized in protein synthesis, where it plays a critical role in forming disulfide bonds. - **Glutathione Synthesis**: - Cysteine is a key component in the synthesis of glutathione, a potent antioxidant. - Glutathione protects cells from oxidative stress by scavenging free radicals and participating in redox reactions. - **Taurine Synthesis**: - Cysteine can also be converted to taurine, an amino acid with various physiological functions, including bile salt conjugation, osmoregulation, and antioxidation. *Regulation of Sulphur Amino Acid Metabolism* - **Nutritional Regulation**: - The availability of dietary methionine and cysteine influences the rate of synthesis and metabolism of these amino acids. - **Enzyme Regulation**: - Enzymes involved in sulphur amino acid metabolism are regulated by allosteric effectors, covalent modifications, and transcriptional control mechanisms. - **Feedback Inhibition**: - High levels of SAM inhibit methionine adenosyltransferase, regulating SAM synthesis. - Accumulation of downstream metabolites like homocysteine can also regulate enzyme activity within the pathways. *Clinical Implications and Disorders* - **Homocystinuria**: - Homocystinuria is an inborn error of metabolism characterized by defective cystathionine β-synthase activity, leading to elevated homocysteine levels. - It manifests with various symptoms, including developmental delays, intellectual disability, ocular abnormalities, and thromboembolic events. - **Methylation Disorders**: - Dysregulation of methionine metabolism can lead to aberrant methylation patterns, contributing to conditions like neural tube defects, cardiovascular diseases, and cancer. - **Glutathione Deficiency**: - Impaired cysteine availability can result in glutathione deficiency, predisposing individuals to oxidative stress-related disorders, such as neurodegenerative diseases, liver damage, and aging-related pathologies. *Conclusion* The metabolism of sulphur-containing amino acids is intricately regulated and essential for various physiological processes, including protein synthesis, antioxidant defense, and metabolic homeostasis. Dysregulation of these pathways can lead to severe clinical manifestations and underscores the importance of understanding sulphur amino acid metabolism in human health and disease.