Serine and Cysteine Synthesis| Harper's Biochemistry| Chapter 27| Lecture 5/9 скачать в хорошем качестве

Serine and Cysteine Synthesis| Harper's Biochemistry| Chapter 27| Lecture 5/9

Synthesis of Serine Serine is a non-essential amino acid, meaning our body can synthesize it. It is mainly synthesized from a glycolytic intermediate called 3-phosphoglycerate. Steps of Serine Synthesis: Step 1: Oxidation 3-phosphoglycerate is oxidized by the enzyme 3-phosphoglycerate dehydrogenase. It forms 3-phosphohydroxypyruvate. NAD⁺ is reduced to NADH. Step 2: Transamination 3-phosphohydroxypyruvate undergoes transamination. The enzyme phosphoserine aminotransferase transfers an amino group from glutamate. Product formed: 3-phosphoserine. Step 3: Dephosphorylation 3-phosphoserine is dephosphorylated by phosphoserine phosphatase. Final product: Serine. So, serine is synthesized from a glycolytic intermediate in three simple steps: oxidation, transamination, and dephosphorylation. Synthesis of Cysteine Cysteine is considered a semi-essential amino acid. Why semi-essential? Because it requires methionine, an essential amino acid, as a sulphur source. Cysteine synthesis occurs through the transsulfuration pathway. Steps of Cysteine Synthesis: Step 1: Formation of Homocysteine Methionine is converted to homocysteine via SAM (S-adenosyl methionine). Step 2: Formation of Cystathionine Homocysteine combines with serine. Enzyme: Cystathionine β-synthase Product: Cystathionine Step 3: Formation of Cysteine Cystathionine is cleaved by Cystathionine γ-lyase. Key Points to Remember Serine is synthesized from 3-phosphoglycerate. Cysteine is synthesized from serine + homocysteine. Methionine provides the sulfur atom in cysteine. Vitamin B6 (Pyridoxal phosphate) is required in the transsulfuration pathway. #SerineSynthesis #CysteineSynthesis #AminoAcidMetabolism #HarperBiochemistry #BiochemistryLecture #MedicalBiochemistry #GlycolysisPathway #TranssulfurationPathway #MethionineMetabolism #HomocysteineMetabolism #SAMCycle #OneCarbonMetabolism #NonEssentialAminoAcids #SemiEssentialAminoAcids #PLPDependentEnzymes #VitaminB6 #GlutathioneSynthesis #ClinicalBiochemistry #Homocystinuria #MetabolicPathways #MBBSBiochemistry #MedicalStudents #USMLEBiochemistry #Step1Biochemistry #BiochemRevision #BiochemForMedicos #AminoAcidSynthesis #3Phosphoglycerate #CystathionineBetaSynthase #PhosphoserinePathway #MetabolismMadeEasy #BiochemistryNotes #BiochemistryConcepts #MedSchoolLife #HarperReview