BIOLCHEM 415 1st Edition Lecture 27 Outline of Last Lecture I. Amino acid degradation occurs when there are excess amino acids in the bodyII. The Urea Cycle is needed to convert toxic ammonium to a nontoxic ureaOutline of Current Lecture III. Diazotrophic microorganisms fix nitrogen IV. Glutamate and glutamine are major entry points of NH4+ into metabolismV. Amino acid carbons come from intermediates of glycolysisCurrent LectureAmino acid synthesis- nitrogen fixation- N usually inert (triple bond)- amino acid biosynthesis- amino acids as biomolecular precursorsNitrogen fixation- N2 NH3- requires lots of energy- Haber-Bosch- industrial process, very energy costly- fertilizer- bacteria - converts to useable form- diazotrophicThese 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.- nitrogenase complex- 2 components- reductase- captures electrons- ATP hydrolysis transfers e- to nitrogenase- nitrogenase- where N2 NH2- 2 ATP required - conformational change in reductase- requires metal bases as catalyst- higher organisms can’t fix nitrogen- therefore ammonia is put into amino acids- glutamate and glutamine are major ammonia donorsAmmonia into amino acids- synthesis of glutamate- glutamate dehydrogenase- α – ketoglutarate glutamate- synthesis of glutamine- glutamine synthethase- glutamate acyl-phosphate intermediate glutamineMore complex biosynthesis = more likely to be an essential amino acidCarbon skeletons- from intermediates- glycolysis, gluconeogenesis, TCA cycle, pentose phosphate pathway- from transamination reactions- catalysts = transaminases- coenzyme pyridoxal phosphate- derived from vitamin B6- Serine, Glycine, and cysteine- 3 – phosphoglycerate- 3 steps to serine- transamine reaction- one more to glycine- serine + tetrahydrofolate (activated one-C units)- serine hydroxymethyl-transferase- tetrahydrofolate- 3 types of activated C (most reduced, intermediate, mot oxidized)- interconvertible- donor and acceptor- not all activated C (not a CO2 carrier)- carries methyl group on N5- only used in methyl transfer by methionine synthaseS-adenosylmethionine (SAM)- CH3 carrier and major –CH3 donor- high transfer potential- transfer: SAM homocysteine- modification of DNA bases- precursor of ethylene- induces fruit ripening- homocysteine methionine- methionine synthase- coenzyme- vitamin B12 dependent reactionActivated methyl cycle- SAM S-adenosyl-homocysteine homocysteine methionineCysteine- serine and homocysteine- high homocysteine- correlates to risk of cardiovascular disease- damage blood vessels?- ROS?- vitamin treatments can lower levelsAmino acids as precursors- synthesize other biomolecules- purines and pyrimidines- histamine vasodilator derived from
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