Amino acid synthesis and degradation and urea cycle :/ Flashcards
How are amino acids obtained
diet
synthesised by body
produced from normal protein turnover (recycled)
what happens if aa are not required
degredated
can be used as a source of energy
can amino acids be stored or not
cannot be stored
List some essential aa from the diet
histidine isoleucine leucine lysine methaionaine phenylalanine threonine typtophan valine
non essential aa examples
alanine aspargine aspartate glutamate serine
conditionally essential aa examples
arginine cysteine glutamine glycine proline tyrosine
what is cystinuria
defective carrier system
- leads to aa in urnine
crystals of cysteine form kidney stones
what happens when nitrogen is consumed in the diet
usually consumed in a form of protien
- hydrolysed to aa by proteolytic enzymes
aa AT into epithelial cells and enter blood
what are the proteolytic enzymes and where are they found
pepsin in stomach
trypsin in pancreas
what is required to make aa
carbon
nitrogen
what can aa be made from
glucose and nitrogen source) aa or ammonia)
can be made from intermediates of glycolysis and the TCA cyecle
what amino acids can be made from aa
non essential amino acids can be made from essential
- donate molecule
why would aa be needed to degradate
excess in diet
some no longer needed
types of aa
Glucogenic aa
ketogenic aa
degredation of glycogenic aa
carbons converted to glucose
degradation of ketogenic
converted to acetylene Ca or acetoacetate(ketone bodies)
what does the amino acid split into
carbon skeleton
amino acid nitrogen
how is nitrogen removed from aa
transamination
- amino group from one aa transferred to another
removal of aa nitrogen as ammonia
glutamate can collect nitrogen from other aa
converted to ammonia by glutamate dehydrogenase in the liver
aa enters urea cycle
what is removal aa nitrogen as ammonia alllostericaly alters by
allosteric regualtion by :
- ATP and GTP (inhibits)
- ADP and Gdp activates
lysosome
protease filled vesicles
ubituitin
small protiens that target proteins for degredation
proteasome
protease complex
proitne is unfolded and degraded
- easier for the protein to be degredated by proteases
what form of nitrogen is not usable in biological systems
NH2
nitrogen that is usabel
NH3
nitrogen that is toxic
NH4+
nitrogen balance
nitrogen ingested (proteins)= nitrogen excreted
children and preganen woman nitrogen balance
+
disease / starvation nitrogen balance
-
nitrogen cycle
5 main steps 1st 2 in mitochondrion other 3 in cytosol nitrogen enters as NH4+ and aspartate ornithine initiates and is regenerated
control of the urea cyle
feed forward regulation
allosteric activate of enzymes
high protein diet or fasting induces urea cycle ensymes
feed forward urea control
high rate of ammonia production higher rate of urea
what enzymes allosterically control the urea cycle
arginine stimulates carbonyl phosphate synthase§
what is the glucose alanine cycle
cycling of nutrients between muscles and liver
what does the glucose alanine cycle dependon
physiological state i.e. fed or fastine
what occurs on fasting
muscle protein broken down to aa
transaminate to form alanine
transported to liver
nitrogen enters urea cycle and pyruvate used to make energy (glucose)
what are Ketone bodies
combination of acetoacetate and beta hydroxybutyrate
what happens to Ketone bodies when glucose is low
reconverted to acetylene coA
enter TCA cycle for entry
what can acetoacetate break down to
acetone spontaneously
what is a diagnostic tool for ketonic states
fruity breath
Phenylketonuria
mutation in phenylalanine hydroxylate
leads to metal retardation
affects nervous tissue
urea cycle disroder
accumulation of ammonia
toxic to NS
inborn errors of aa metabolism
deficient enzymes in aa metabolism
leads to accumulation of harmful producs
what are some inborn errors in aa metabolism examples
phenylketonura
urea cycle disorders
