Lecture 20 - 022311

Lecture 20 - 022311 - Lectures 20 Amino Acid Biosynthesis 1...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Lectures 20 Amino Acid Biosynthesis
Background image of page 1

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

View Full DocumentRight Arrow Icon
2 Amino Acid synthesis: three key problems Nitrogen fixation reducing inert nitrogen gas to 2 ammonia molecules Microorganisms Stereochemical control of amino acids All amino acids except glycine are chiral High fidelity to generate correct isomer Transamination at -carbon Pyridoxal phosphate (PLP) involved Regulation of amino acid synthesis Only synthesized when needed Negative feedback (product inhibits the pathway)
Background image of page 2
Nitrogen fixation reducing inert nitrogen gas to 2 ammonia molecules Microorganisms: For example: symbiotic Rhizobium bacteria in the roots of leguminous plants 3 Newly fixed nitrogen on earth: •Nitrogen-fixing microorganisms: 10 11 kg N 2 /year, 60% •Lightning and ultraviolet radiation: 15% •Industrial processes: 25%
Background image of page 3

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

View Full DocumentRight Arrow Icon
Nitrogen fixation: nitrogenase complex •Nitrogenase inactivated by O 2 •Leghemoglobin binds to O 2 to keep free [O 2 ] low in the leguminous plants •Reduced ferredoxin comes from photosynthesis or oxidative processes •8 e - transferred and 2 ATP required for each e - transferred N 2 + 8 e - + 8 H + + 16 ATP+16H 2 O -> 2NH 3 + H 2 + 16 ADP + 16 P i ATP hydrolysis makes reaction kinetically feasible by reducing activation barriers 4 Molybdenum-iron protein
Background image of page 4
Nitrogenase complex: reductase component •Iron-sulfur proteins •A dimer bridged by a 4Fe-4S cluster (electron carrier) •ATP hydrolysis triggers conformational change (closer to nitrogenase) 5
Background image of page 5

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

View Full DocumentRight Arrow Icon
Nitrogenase complex: nitrogenase component 2 β 2 tetramer •P cluster: 8 irons, 7 sulfides, 6 Cys •Store e - •FeMo cofactor: 1 molybdenum, 7 irons, 9 sulfides •Reduce N 2 (Nitrogen fixation) 6
Background image of page 6
Nitrogen fixation: ammonium ion assimilated into amino acids through glutamate and glutamine
Background image of page 7

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

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/15/2011 for the course CHEM 114B taught by Professor Wang during the Spring '09 term at UCSD.

Page1 / 51

Lecture 20 - 022311 - Lectures 20 Amino Acid Biosynthesis 1...

This preview shows document pages 1 - 8. Sign up to view the full document.

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