Lecture 13 amino acid synthesis

Lecture 13 amino acid synthesis - BergTymoczkoStryer...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Biochemistry Chapter 24: The Biosynthesis of Amino Acids Copyright © by W. H. Freeman and Company   Berg • Tymoczko • Stryer
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Overview Nitrogen fixation Amino Acid Biosynthesis Amino acids as biomolecular precursors
Background image of page 2
Nitrogen fixation : process that reduces N 2 to NH 3 Bond energy: 225 kcal/mol Haber-Bosch process (~25%): 500 o C, 300 atm, catalyst Microorganisms, e.g. symbiotic Rhizobium (in plant root nodules), contribute about 60% of newly fixed nitrogen
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Nitrogenase complex: Fixes nitrogen Fe-S clusters carry single electrons to the nitrogenase. Conformational change induced by ATP hydrolysis brings reductase close to the Mo-Fe center of nitrogen reduction. N 2 + 8e- + 8 H + + 16 ATP + 16 H 2 0 ---> 2 NH 3 + H 2 + 16 ADP + 16 Pi 2 ATP/e-
Background image of page 4
Higher organisms are unable to fix nitrogen mmonia is assimilated into amino acids through glutamate and glutamin **two major nitrogen donors** X
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Synthesis of Glutamate Enzyme: glutamate dehydrogenase Protonated Schiff base Intermediate mmonia is assimilated into amino acids through glutamate and glutamin Establishes stereochemistry—L-glutamate Yes, same enzyme (Lec 11/12)
Background image of page 6
Synthesis of Glutamine Enzyme: glutamine synthetase *Key regulatory step in nitrogen metabolism major nitrogen donors: glutamate and glutamine mmonia is assimilated into amino acids through glutamate and glutamin on’t)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Glutamine synthetase is regulated at multiple levels Directly regulated by adenylylation--the covalent attachment of AMP AT: adenylyl transferase Gln (product) α -KG ATP phosphorolysis
Background image of page 8
Name four reactions in which ammonia is assimilated. glutamate dehydrogenase glutamine synthetase Don’t forget the urea cycle! How is glycine synthesized? CO 2 + NH 4 + + N 5 , N 10 -methyleneTHF + NADH glycine + THF + NAD + Glycine synthase Carbamoyl phosphate synthetase Only 2 are major N donors
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
* * A unifying feature of amino acid biosynthesis: carbon skeletons come from intermediates of glycolysis , the citric acid cycle , or the pentose phosphate pathway (Phe, Trp, His)
Background image of page 10
Arginine glutamate ornithine α -KG Urea Cycle TA Glutama te DHase
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tyrosine *: phenylketonuria
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 41

Lecture 13 amino acid synthesis - BergTymoczkoStryer...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online