Biosynthesis of Amino Acids, Nucleotides, and Related Molecules Flashcards
What needs to happen to atmospheric nitrogen for it to be available to most living organisms?
Needs to be reduced (fixed)
Where does fixation of atmospheric N2 take place?
In some free-living bacteria and some bacteria in the root nodules of plants
5 step overview of nitrogen cycle
- Formation of ammonia by bacterial fixation of N2
- Nitrification of ammonia to nitrate by soil organisms
- Conversion of nitrate to ammonia by higher plants
- Synthesis of AA’s from ammonia by all organisms
- Conversion of nitrate to N2 by denitrifying soil bacteria.
How is fixation of N2 as NH3 carried out? And how is it regulated?
By nitrogenase complex, in a reaction which requires large amount of ATP and reducing power. Regulated by supply of NH3.
Where is reduced nitrogen incorporated to first in living systems?
AA’S. Then a variety of biomolecules, including nucleotides.
What is the key entry point for nitrogen in living systems?
Glutamate
What do glutamate and glutamine act as in a wide range of biosynthetic reactions?
Nitrogen donors
What is glutamine synthetase and what does it do?
Is a main regulatory enzyme of nitrogen metabolism. Catalyzes formation of glutamine from glutamate
What are pyridoxal phosphate, tetrahydrofolate and S-adenosylmethionine and where do they act?
Biological cofactors. AA and nucleotide biosynthetic pathways.
What is Pyridoxal phosphate required for?
Transamination reactions involving glutamate and other AA transformations
What are tetrahydrofolate and S-adenosylmethionine required for?
One-carbon transfers
What do glutamine amidotransferases do?
Catalyze reactions thatincorporate nitrogen derived from glutamine
What synthesize all 20 common AA’s?
Plants and bacteria
How many common AA’s can mammals synthesize and how do they get the rest?
About half. Rest come from diet.
What is the name of AA’s that mammals need from the diet?
Essential AA’s
