urea cycle - created from Mind Map

Página 1

UREA CYCLE-

mitochondria and cytosol

cps 1 - nitrogen metabolism , cps 2 - nitrogen anabolism , depends upon nag and glutamate resp

mitoch-cytosol shift happens in ornithine and citrulline

ornithine is a non essential aa basic formed from arginase

succininc acid-oaa-aspartate

net energy is four high energy bonds , sometimes one bcuz of fumarate

nag synthase is imp for cps 1....

cps1 is rate limitn and regulating major enxyme

hyperammonia maybe due to liver isfunction as urea cycle isnt working ir bcuzz of collateral connection

genetic deficiency four of them are autososamal recessive except for ornithine transcarb..

fibrosis-shunts-colateral circulation - diagnosisi-portal hypertension - varices-

SOME BASIC OCNCEPTS

AMMONIA INC , GLUTAMINE INC , GLUTAMIDE INC

ammino acid metabolism depends upon cellylar energy contennt as c skeelton metab depends upon tca

asparagine , aspartate arginine dont get confused - asparagine is amminated form of aspartate; both form oaa

its a lot like glutamine , glutamate , enzyme sequentially required is deamination and then transamination

IMPORTANCE of glycine- collagen syn (hydroxyproline), glutathione (glycine , glutamate, cysteine) purine , hippuric acid ()treatment)

GABA - INSULIN -DIABETES MELLITS-

LIVER CIRRHIROSIS - BLOOD SUPPLY AFFECTED DUE TO FIBROSIS - XENOBIOTICS ABSENT - PORTAL HYPERTENSION-ENCEPHALOPATHY

hyperammonia -

treatment - dietary protein -give keto acids instead of eaa/ diff ways of ecreting urea/

benzoate na d phenylalanine given to pateints to excreete glycine and glutamine in the form of phenylacetylglatmine and hippuric acid in the form of urine.. i e glycine and glutamin react , bcome water soluble.

DISORDERS OF AA METABOLISM

CYSTINURA- renal tubular reabsorption of cysteine - penicillamine

hartnups disease- intestinal transport of neutral

PHENYLKETONEURIA - HYDROXYLASE ENZYME AB /PARTIALLY / DHP REDUCTASE ENZYME /THB DEFicinecy

phenylketonuria

phenylalanine inc/ phenylpyuruvate in urine /phrnylactate/acetate

mental retardation (beware all pregnant pku pateinets)

phenylalanin decrease intake / thb inrease intake

prognosis- guthrie bacterial test - bacterial colonies in posiitive patient/ fecl3 test blue

alkaptonuria - homogentisate enzyme absent - reqd in tyrosine metabolism - hydroquinone- urine -oxidised- benzoquinone-dark black -

ochronosis

Antipyridoxine drugs should not be given in excesss as they bring a halt to decarobxylation of glutamate ...convulsion

Histidine - semi essential bcuz body requirement is less ; also storage in the form of carnosine in muscles .

Arginine- semi essential - requirement is low

Protein turnover- total protein content is same ; i e flux is zero ; influx =efflux; synthesis = degradation

protein metabolism - amino acids - 80 % recycled ..

Amino acid balance - nitrogen balance -

one reaction gets

OXIDATIVE DEAMINATION IS Special - nad and nadp both are co substrates and atp and gtp both acts ac allosteric regulators ... when cellular energy is .ow then this reaction is stimulated (PROTEIN CATABOLISM releases energy)

Ammonium - IS NEUROTOXIC !!!!! Why ?? - ammonia inhibits glutaminase as a result of which glutamate con decreases- and coma .. also glutamine inc osmotically CTIVE INCREASES -astrocytes swwell up -oedema - encephalopathy

how can hyperammonia occur - urea cycle isnt working ie liver isnt working- fibrosi ?? and collateral links bw hepatic portal veins and systemic veins

INTEGRATION OF METABOLISM

glucocorticoids secreted in sever stress ..

liver glycogen sustains for 36 hours only

adipose tissue enoguh to last for 1-3 months

less than 50 % proteins when metabolised - you are dead-respiratory muscles failed

Histamine - histamine decarboxylase - histidine