Amino avid

OVERVIEW OF NITROGEN METABOLISM-SYNTHESIS
Group members:
Nguyễn Đồng Duy BT070113
Quách Lê Hải Đăng BT070103
OVERVIEW
OVERVIEW
FUNCTIONS OF NITROGEN
Structural function: materials to build up many important organic matters: protein, amino acid, phospholipid, chlorophyl, alkaloids, nitrogen base, nucleotide, ADP, ATP.
Regulation metabolism: build up enzyme, B-group vitamin, hormone.
Also effects on the viscosity of cytosol in cell.
THE METABOLISM OF SOIL BACTERIA MAKES NITROGEN AVAILABLE TO PLANTS


The atmosphere is nearly 80% nitrogen that is gaseous N2, and plants cannot use nitrogen in that form. For plants to absorb nitrogen, N2 must first be converted  ammonium (NH4+)or nitrate (NO3-).
Over the short term, the main source of nitrogenous minerals is the decomposition of humus by microbes, including ammonifying bacteria: called nitrogen fiaxation
The conversion of atmospheric N2  ammonia (NH3) is a complicated, multi-step process, but we can simplify nitrogen fixation by just indicating the reactants and products by nitrogenase and hydrogenase
Enzyme(Fe)(Mo) + N2 => Enzyme(Fe)(Mo)(N2) => NH3
Nitrogen-fixing bacteria are most abundant in soils rich in organic material, which provides fuel for cellular respiration
N2 (organic matter)  NH4+ nitrifying bacteria  NO3-  plant  NO3- / organic compounds

SYMBIOTIC NITROGEN FIXATION RESULTS
FROM INTRICATE INTERACTIONS BETWEEN ROOTS AND BACTERIA

Many plant families include species that form symbiotic relationships with nitrogen-fixing bacteria that give roots a built-in source of fixed nitrogen for assimilation into organic compounds.
Most of the research on symbiotic nitrogen fixation has focused on agriculturally important members of the legume family, including peas, beans, soybeans, peanuts, alfalfa, and clover.
A legume’s roots have swellings called nodules composed of plant cells that contain nitrogen-fixing bacteria of the genus Rhizobium ("root living").
Inside the nodule, Rhizobium bacteria assume a form called bacteroids, which are contained within vesicles formed by the root cell. Each legume is associated with a particular species of Rhizobium.
Some root nodules have a reddish color owing to a molecule called leghemoglobin
NH4+ is assimilated into amino acids by way of Glutamate & Glutamine
The α-amino group of most amino acids comes from the α-amino group of glutamate by transamination
Glutamate synthesized from NH4+ & α-ketoglutarate: enzyme glutamate dehydrogenase
Glutamine is major nitrogen donor
All organisms: glutamate dehydrogenase and glutamine synthetase
Most prokaryotes contain glutamate synthase


When NH4+ is limitting,most of glutamate is made by the squential action of glutamine synthetase and glutamate synthase. The sum reactions:
AA biosynthesis
Most bacteria and plants can synthesize all 20 aa’s, most animals can only synthesize 11, others are essential components
of diet.( Escherichia coli→ 20 aas)
11 ne- from intermediate of CAC and other major pathway by simple reactions
9 e- complex pathway
Their carbon skeletons come from intermediates of glycolysis, PPP, CAC.
6 biosynthetic families
Oxaloacetate and pyruvate
Transamination
Transamination
Amidation of Asp
(N from Gln)
One-step synthesis of ne aas
Ne aas alanine & aspartate → pyruvate and oxaloacetate. Each acquires amino group from glutamate in a transamination with PLP cofactor


Asparagine → by the amination of aspartate

In mammals,nitrogen donor is glutamine rather than NH4+, as in bacteria (high levels of NH4+ are toxic)
Another is hydroxylation of phenylalanine (e aas) to tyrosine. Tyrosine is e aas in people lacking phenylalanine hydroxylase
Serine Family
Serine synthesized from 3-PG
Glycine derived from serine via Folate
pathway
Serine accepts sulfhydryl from
homocysteine (1C metabolism)
Tetrahydrofolate carries activated one-carbon units
PYRIDOXAL PHOSPHATE
In plants and bacteria…
In mammals…
Aromatic
Amino Acids
PEP + E-4-P  Shikimate  Chorismate Prephenate & Anthranilate (key branchpoint intermediate)
Chrosimate is a precursor of phe, tyr, tryp via separate paths
PRPP an activacted form of ribose phosphate. Is the key intermediate in synthesis histidine, purine & pyrimidine

Aromatic AA’s
5-phosphoribosyl-1-pyrophosphate(PRPP)
Ribose 5-phosphate
Molecules derived from AAs
Porphyrins
Neurotransmitters
Nucleotides

PORPHYRINS
PORPHYRINS
NEUROTRANSMITTERS
NUCLEOTIDES
Nearly identical in all living organisms
Purine ring built up
Pyrimidine ring synthesized as orotate
Enzyme complexes
Important precursors:
5-phosphoribosyl-1-pyrophosphate (PRPP)
Amino acids
Ribose-5-P + ATP PRPP + AMP

Purine nucleotide biosynthesis
PYRIMIDINE NUCLEOTIDE BIOSYNTHESIS
Regulation of nitrogen metabolism
Regulation of amino acid synthesis
Allosteric feedback inhibition
Concerted inhibition
Sequential feedback inhibition
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