BBMB 405 1st Edition Lecture 14Outline of Last Lecture XIV. Chapter 22: Fatty Acid MetabolismC. Elongation and unsaturation of fatty acids are accomplished by accessory enzyme systems (Continued)D. Handout (2/9)E. Acetyl CoA Carboxylase plays a key role in controlling fatty acid metabolismXV. Chapter 23: Protein Turnover and Amino Acid CatabolismA. Handout (2/11)B. Proteins are degraded to amino acidsOutline of Current Lecture XV. Chapter 23: Protein Turnover and Amino Acid CatabolismB. Proteins are degraded to amino acidsC. Protein Turnover is tightly regulatedD. The First step in amino acid degradation is the removal of nitrogenE. Ammonium ion is converted into urea in most terrestrial vertebratesCurrent LectureXV. Chapter 23: Protein Turnover and Amino Acid CatabolismStart (on overhead): - Intracellular proteolysis1. Use of “stored” amino acidsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2. Eliminate abnormal proteins3. Permit regulation of [enzymes]- Three methods of intracellular proteolysis1. Lysosome system2. Ubiquitin system3. Ca-activated proteases in muscleB. Proteins are degraded to amino acids (Continued)8. Cellular proteins are degraded at different rates: some proteins are short lived anddegrade quickly (hemoglobin is limited only by life of red blood cell)C. Protein Turnover is tightly regulated1. Ubiquitin tags proteins for destructiona. Contributes to intracellular turnoverb. Ubiquitin binds to lysine 48 making an isopeptide bond (through ATP hydrolysis), then a few more are added making polyubiquitinated protein for degredationc.d. ATP driven ubiquitin conjugatione.2. Proteasome digests ubiquitin-tagged proteinsa. Proteasome: large protease complex that digests ubiquitinated proteinsb. Ends of barrel are control points, target protein goes through center and is unfoldedc.d. Overhead:i. Gardasil: human papilloma virus- Prevents cervical cancer- Causes excessive activation of E3 for P53 (tumor suppressor protein) degradation- If [P53] is decreased then less chance of mutation and less chance of cancerii. Other E3 disease:- Early Onset Parkinson’s disease: ubiquitin system too slow, notcontrol cyclin which controls cell division so cells divide to quickly- Angelman syndrome (mental retardation)iii. Cystic Fibrosis:- Deficiency of chloride transport protein in lung, pancreas and liver (ATP dependent)- Mutation in phenylalanine (ATP binding domain)- Mutant protein not folded properly and degraded by ubiquitin systeme. Handout (2/11): no lysosome in brain, protein degraded by endocytosis then creating a phagosome (origin: bacteria virus) or endosome (origin: protein) then fusion with lysosome where protein is degraded to amino acids by proteases; lysosome hydrolyze protein in low pH usually pH 5, lysosome activity increases in muscle atrophyf. Rumen: Dietary protein is substrate for microbes which makes amino acids which are then degraded further to make ATP then animal uses ammonia to make amino acids and in turn protein; rumen live on microbial proteins3. Protein degradation can be used to regulate biological functionD. The First step in amino acid degradation is the removal of nitrogen1. Alpha-amino groups are converted into ammonium ions by oxidative demination of glutamatea. Aminotransferases (aka transaminases): catalyze transfer of alpha amino group from alpha amino acid to alpha ketoacid; reactions are reversibleb.c. Glutamate dehydrogenased. Show that alpha ketoglutarate and glutamate work togethere.f. Know amino acid structures, lose N group to make ammonia and what else (alanine makes pyruvate)2. Mechanism: pyridoxal phosphate forms Schiff-base intermediates in aminotranserases3. Asparate aminotransferase in archetypal pyridoxal-dependent transaminase4. Pyridoxal phosphate enzymes catalyze a wide array of reactionsa. Coenzyme: Vitamin B12b. Focus on: Transamination, decarboxylation, deamination5. Serine and threonine can be directly deaminateda. Serine pyruvate + NH4+b. Threonine alpha-ketobutyrate + NH4+6. Peripheral tissues transport nitrogen to the liverAlanine CoriMuscle 2 Alanine 2 Pyruvate 2 LactateGlycolysis +2ATPGlucoseBlood 2 Alanine 2 Glucose 2 LactateLiver GlucoseGluconeogenesis -2ATP2 Alanine 2Pyruvate 2 Lactate2 Alanine NH2 + 4ATPDeaminationUreaDegraded: transferred to pyruvate and make glucoseE. Ammonium ion is converted into urea in most terrestrial vertebrates1. Overview (went through in class, will go through in more detail next lecture)2.3. Make 35g/day of
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