BBMB 405 1st Edition Lecture 16Outline of Last Lecture XV. Chapter 23: Protein Turnover and Amino Acid CatabolismE. Ammonium ion is converted into urea in most terrestrial vertebratesF. Carbon atoms of degraded amino acids emerge as major metabolic intermediatesOutline of Current Lecture XV. Chapter 23: Protein Turnover and Amino Acid CatabolismF. Carbon atoms of degraded amino acids emerge as major metabolic intermediatesG. Inborn errors of metabolism can disrupt amino acid degradationCurrent LectureXV. Chapter 23: Protein Turnover and Amino Acid CatabolismF. Carbon atoms of degraded amino acids emerge as major metabolic intermediates (con’t)1. Amino acids produce carbon skeletons that make intermediates of TCA cycle2. Emphasize catabolism of Ala, Ser, Gly, Asp, AspNH2, Glut, GlutNH2, Meth3. Non glucogenic amino acids: leucine, lysine, phenylalanine, tryptophan, tyrosine4.These 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.5. Catabolism of amino acids: Alanine, serine, glycine (make pyruvate); aspartate, asparagine (make oxyloacetate); glutamate, glutamine (make alpha-ketoglutarate); methionine6. Pyruvate as an entry point into metabolism for number of amino acids7. Oxaloacetate as an entry point into metabolism for aspartate and asparagine8. Alpha-ketoglutarate as entry point into metabolism for five-carbon amino acidsa. Glutamate dehydrogenase using NAD+Glutamine via glutaminase glutamate via Alpha ketogluterate Transamination (alpha keto acid to aa)b. c. Do not memorize pathway of amino acids to glutamate9. Succinyl coenzyme A is point of entry for several nonpolar amino acids10. Methionine degradation requires formation of key methyl donor, S-adenosylmethioninea. Do memorize (I think)b. Handout 2/18: asparagine is used to treat leukemia; refer to this handout for alternate pathway for methionine catabolism, SAM is a methyl donor, SAH is one less carbon of SAM, high concentrations of homocysteine in blood proves to increase risk for heart disease, we can make our own cysteine but need methionine; note: I would memorize reaction on handout11. The branched-chain amino acids yield acetyl CoA, acetoacetate, or propionyl CoAa. Muscle process branched-chain amino acids, liver is very poor at degradation of branched-chain amino acidsb. Luecine is converted into acetyl CoA and acetoacetate, it is not glucogenic because the end products are not glucogenicc.d.e.f. “The degradative pathways of valine and isoleucine resemble that of leucine.” (Biochemistry, p. 693)g. Handout (2/18) Maple syrup disease: autosomal recessive disease were L, V, I cannot be converted to Acyl-CoA because alpha keto acid dehydrogenase is missing or defective; alpha keto acid accumulateds and goes out in urine which now smells like maple syrup, leads to severe neuro development problems, cure: feed minimum branch chain amino acids12. Oxygenases are required for degradation of aromatic amino acidsa.b. Can’t make tyrosine unless have this reactionc.d. Reductant is tetrahydrobiopterin a derivative of biopterine.f.g. Homogentisate: require O2 enzyme and if don’t have it is excreted into urine. When make contact with oxygen in air polymerize and turn black. Disease called alcaptonuriah.i. “Nearly all cleavages of aromatic rings in biological systems are catalyzed by dioxygenases.” (Biochemistry, p. 695)j. Handout (2/18): Phenylketonuria (PKU) is first genetic disorder that babies are tested for, test concentration of phenylalanine, feed phenylalanine if have disease, assay for maple syrup disease:G. Inborn errors of metabolism can disrupt amino acid degradationa. KIC (from leucine degradation) release CO2 and create HMB (hydroxymethyl butyrate); HMB leads to more muscle, makes muscle grow more efficientlyb. Cystinuria: cysteine in urine- Error in transport of cysteine in kidney which leads to crystallization- Autosomal recessive- Have to drink water and eat less methioninec. Handout (2/20): Rhizobium has nitrogenase which is sensitive to oxygen so rhizobium also has leghemoglobin which binds to oxygen and reaction can take place; nitrogenase reaction (convert nitrogen to
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