Term
| some sources of amino acids |
|
Definition
-dietary protein
-degradation of unneded or defective cellular proteins |
|
|
Term
|
Definition
| the degradation and resynthesis of proteins |
|
|
Term
| some proteins that are short lived |
|
Definition
| those that are involved in metabolic regulation |
|
|
Term
| some causes of defective proteins |
|
Definition
-errors in translation
-oxidative damage
-altered in other ways with the passage of time |
|
|
Term
| something that happens to excess amino acids |
|
Definition
| they are first used as building blocks for anabolic rxns, such as protein synthy and nucleotide synth |
|
|
Term
| what happens to excess amino acids after then needs for anabolic rxns are met? |
|
Definition
| the amino acids are degraded and the C skeletons are used in catabolism or anabolism |
|
|
Term
| why it's important to safely remove the excess N from amino acids |
|
Definition
| because excess N in the form of ammonia is toxic |
|
|
Term
| how most vertebrates get rid of excess N from amino acids |
|
Definition
| convert the ammonia into urea, which is then excreted |
|
|
Term
| the first step in the degradation of amino acids |
|
Definition
|
|
Term
| the major site of amino acid degradation in mammals |
|
Definition
|
|
Term
|
Definition
| what's left over after the N is removed from amino acids |
|
|
Term
| what happens after the N is removed fro amino acids? |
|
Definition
| the resulting α-ketoacids so that the C skeletons can enter the metabolic mainstream as precursors of glucose or citric acid cycle intermediates |
|
|
Term
| how alpha-amino groups are converted into ammonium ions |
|
Definition
| by the oxidative deanimation of glutamate |
|
|
Term
| depiction of oxidative deanimation of glutamate |
|
Definition
|
|
Term
| aminotransferases aka transaminases |
|
Definition
catalyze the transfer of an α-amino groupfrom an α-amino acid to an α-ketoacid
generally funnel α-amino groups from a variety of amino acids to α-ketoglutarate for conversion into ammonia |
|
|
Term
| depiction of the function of aminotransferases aka transaminases |
|
Definition
|
|
Term
| aspartate aminotransferase |
|
Definition
| catalyzes the transfer of the aminotransferases aka transaminases-amino group of aspartate to aminotransferases aka transaminases-ketoglutarate |
|
|
Term
| depiction of the function of aspartate aminotransferase |
|
Definition
|
|
Term
|
Definition
| catalyzes the transfer of the amino group of alanine to aminotransferases aka transaminases-ketoglutarate |
|
|
Term
| depiction of the function of alanine aminotransferase |
|
Definition
|
|
Term
| depiction of the oxidative deanimation of glutamate, regenerating α-ketoglutarate |
|
Definition
|
|
Term
|
Definition
| catalyzes the oxidative deanimation of glutamate |
|
|
Term
| depiction of the function of glutamate dehydrogenase |
|
Definition
|
|
Term
| something unusual about glutamate dehydrogenase |
|
Definition
| it can use either NADH or NADPH as reducing power |
|
|
Term
| how toxic free ammonia is sequestered |
|
Definition
| some liver specific enzymes in mitochondria such that there's compartmentalization |
|
|
Term
| how glutamate dehydrogenase is regulated in mammals, but not other organisms |
|
Definition
| allosterically inhibited by GTP and stimulated by ADP |
|
|
Term
|
Definition
| this is formed on an enzyme when a product is replaced by substrate before the rxn is complete |
|
|
Term
| the net rxn catalyzed by aminotransferases and glutamate dehydrogenases |
|
Definition
| α-amino acid + NAD(P)H+ + H2O --> α-ketoacid + NH4+ + NAD(P)H +
H+ |
|
|
Term
| what happens to the N atoms of amino acids, except for serine and threonine, before their removal? |
|
Definition
| they get transferred to α-ketoglutarate before their removal |
|
|
Term
| how the N atoms of serine and threonine are removed |
|
Definition
| they are directly deanimated |
|
|
Term
|
Definition
| catalyze the direct deanimation of serine, which yields pyruvate and ammonia |
|
|
Term
|
Definition
| catalyze the direct deanimation of thrionine, which yields α-ketobutyrate and ammonia |
|
|
Term
| the prosthetic group on serine dehydratase and thrionine dehydratase |
|
Definition
| pyridoxal phosphate (PLP) |
|
|
Term
| depiction of the function of serine dehydratase |
|
Definition
|
|
Term
| depiction of the function of threonine dehydratase |
|
Definition
|
|
Term
| depiction of how ammonia is converted into urea in most terrestrial vertibrates |
|
Definition
|
|
Term
| the amino acids liver can not deanimate |
|
Definition
| the branched-chain amino acids leucine, valine, and isoleucine |
|
|
Term
| one way muscle uses branched-chain amino acids |
|
Definition
|
|
Term
| how N from amino acids is processed in the muscle |
|
Definition
| gets released into a form that can be absorbed by the liver and converted into urea |
|
|
Term
| 2 principal transport forms in which N is transported from muscle to liver |
|
Definition
|
|
Term
|
Definition
| evidently the interconversion of alanina and glucose |
|
|
Term
| depiction of the glucose-alanine cycle |
|
Definition
|
|
Term
| when muscles use branched-chain amino acids as fuel |
|
Definition
| during prolonged exercise and fasting |
|
|
Term
| a key transport form of N |
|
Definition
|
|
Term
|
Definition
| catalyzes the synthesis of glutamine from glutamate and ammonia in an ATP-dependent rxn |
|
|
Term
| depiction of the function of glutamine synthetase |
|
Definition
|
|
Term
| how ammonia from the breakdown of amino acids can be used by the organism |
|
Definition
| in the biosynthesis of N compounds |
|
|
Term
| what happens to excess ammonia in most terrestrial vertebrates? |
|
Definition
| gets converted to urea by the urea cycle and excreted |
|
|
Term
|
Definition
| organisms that use the urea cycle to convert excess ammonia into urea to ne excreted |
|
|
Term
| depiction of the urea cycle |
|
Definition
|
|
Term
|
Definition
|
|
Term
| urea cycle begins in ______ with ______ |
|
Definition
| mitochondrial matrix
coupling of free NH4+ and HCO3- to form carbamoyl phosphate |
|
|
Term
| carbamoyl phosphate synthetase I (CPS I) |
|
Definition
| catalyzes the coupling of free NH4+ and HCO3- to form carbamoyl phosphate |
|
|
Term
| the committed step in the urea cycle |
|
Definition
| the coupling of free NH4+ and HCO3- to form carbamoyl phosphate using carbamoyl phosphate synthetase I (CPS I) |
|
|
Term
| depiction of the rxn sequence that forms carbamoly phosphate |
|
Definition
|
|
Term
| why the synthesis of carbamoyl phosphate is irreversible |
|
Definition
| because it consumes 2 ATP's |
|
|
Term
| the key regulatory enzyme for urea synthesis |
|
Definition
| carbamoyl phosphate synthetase |
|
|
Term
| when carbamoyl phosphate synthetase is maximally active |
|
Definition
| when amino acids are being metabolized for fuel use |
|
|
Term
| N-acetylglutamate synthase |
|
Definition
| catalyzes the synthesis of N-acetylglutamate |
|
|
Term
| depiction of the function of N-acetylglutamate synthase |
|
Definition
|
|
Term
| N-acetylglutamate synthase is itself activated by... |
|
Definition
|
|
Term
| how the urea cycle begins |
|
Definition
| carbamoyl phosphate reacts with ornithine to begin the urea cycle |
|
|
Term
| ornithine transcarbamoylase |
|
Definition
| catalyzes the rxn of ornithine with carbamoyl phosphate to form citrulline |
|
|
Term
| depiction of the function of ornithine transcarbamoylase |
|
Definition
|
|
Term
| argininosuccinate synthetase |
|
Definition
| catalyzes the formation of argininosuccinate from citrulline and aspartate |
|
|
Term
| depiction of the function of argininosuccinate synthetase |
|
Definition
|
|
Term
| argininosuccinase aka argininosuccinate lyase) |
|
Definition
| cleaves argininosuccinate into arginine and fumarate |
|
|
Term
| depiction of the function of argininosuccinase aka argininosuccinate lyase |
|
Definition
|
|
Term
|
Definition
| catalyzes the hydrolysis of arginine to form urea and ornithine |
|
|
Term
| the net rxn of urea synthesis |
|
Definition
| CO2 + NH4+ + 3 ATP + aspartate + 2 H2O --> urea + 2 ADP + 2 Pi + AMP + PPi + fumarate |
|
|
Term
| importance of fumarate derived from urea cycle |
|
Definition
-fumarate is a precursor for glucose
-fumarate can be hydrated to malate, which is an intermediate in the citric acid cycle |
|
|
Term
| the urea cycle, citric acid cycle, and transamination of oxaloacetate are linked by... |
|
Definition
|
|
Term
| depiction of the connection between the urea cycle, the citric acid cycle, and the transamination of oxaloacetate |
|
Definition
|
|
Term
| the strategy of amino acid degradation |
|
Definition
| to transform the C skeletons into major metabolic intermediates that can be converted into glucose or oxidized by the citric acid cycle |
|
|
Term
| the C skeletons from the 20 fundamental amino acids are funneled into these 7 molecules. |
|
Definition
-pyruvate
-acetyl CoA
-acetoacetyl CoA
-α-ketoglutarate
-succinyl CoA
-fumarate
-oxaloacetate |
|
|
Term
|
Definition
amino acids that are degraded into acetyl CoA or acetoacetyl CoA
they are called this because they give rise to ketone bodies or fatty acids but can not be used to synthesize glucose |
|
|
Term
| ketogenic amino acids give rise to... |
|
Definition
| ketone bodies or fatty acids |
|
|
Term
| ketogenic amino acids give rise to ketone bodies or fatty acids but can not be used to synthesize... |
|
Definition
|
|
Term
|
Definition
| amino acids that are degraded to pyruvate, α-ketoglutarate, succinyl CoA, fumarate, or oxaloacetate |
|
|
Term
| what oxaloacetate and pyruvate derived from the degradation of glucogenic amino acids can be used for |
|
Definition
|
|
Term
| the only 2 amino acids that are solely ketogenic |
|
Definition
|
|
Term
| the amino acids that are both ketogenic and glucogenic |
|
Definition
-threonine
-isoleucine
-phenylalanine
-tryptophan
-tyrosine |
|
|
Term
| the amino acids that are solely glucogenic |
|
Definition
-alanine
-cysteine
-glycine
-serine
-threonine
-asparagine
-aspartate
-methionine
-valine
-arginine
-glutamate
-glutamine
-histidine
-proline |
|
|
Term
| how the poathways of amino acid degradation are identified |
|
Definition
| by entry point into metabolism |
|
|
Term
| depiction of the fates of the C skeletons of amino acids |
|
Definition
|
|
Term
| amino acids that enter the metabolic mainstream by pyruvate |
|
Definition
-alanine
-serine
-cysteine
-glycine
-threonine
-tryptophan |
|
|
Term
| how alanine gets converted into pyruvate |
|
Definition
transamination of alanine
alanine + α-ketoglutarate <--> pyruvate + glutamate |
|
|
Term
| how serine gets converted into pyruvate |
|
Definition
| deanimation by dehydratase
serine --> pyruvate + NH4+ |
|
|
Term
|
Definition
| catalyzes the deanimation of serine to pyruvate |
|
|
Term
| depiction of the function of serine dehydratase |
|
Definition
|
|
Term
| depiction of pyruvate formation from amino acids |
|
Definition
|
|
Term
| the amino acids that enter the mainstream metabolism by way of oxaloacetate |
|
Definition
|
|
Term
| how aspartate enters mainstream metabolism by way of oxaloacetate |
|
Definition
gets directly transaminated to oxaloacetate
aspartate + α-ketoglutarate <--> oxaloacetate + glutamate |
|
|
Term
| how asparagine enters mainstream metabolism by way of oxaloacetate |
|
Definition
| gets hydrolyzed into aspartate, which is then transaminated into oxaloacetate |
|
|
Term
|
Definition
| catalyzes the hydrolysis of asparagine into aspartate and NH4+ |
|
|
Term
| amino acids that can enter mainstream metabolism by α-ketoglutarate |
|
Definition
-glutamine
-arginine
-proline
-histidine
-glutamate |
|
|
Term
| how glutamate enters mainstream metabolism by way of α-ketoglutarate |
|
Definition
| gets converted into α-ketoglutarate |
|
|
Term
| how glutamine, proline, arginine, and histidine enter mainstream metabolism by way of α-ketoglutarate |
|
Definition
| by getting converted into glutamate, which can be converted into α-ketoglutarate |
|
|
Term
| depiction of α-ketoglutarate formation from amino acids |
|
Definition
|
|
Term
| depiction of histidine degradation (the conversion of histidine into glutamate) |
|
Definition
|
|
Term
| how glutamine enters mainstream metabolism by way of α-ketoglutarate |
|
Definition
| gets hydrolyzed into glutamate, which can be converted into α-ketoglutarate |
|
|
Term
|
Definition
| hydrolyzes glutamine into glutamate and NH4+ |
|
|
Term
| depiction of glutamate formation from proline and arginine |
|
Definition
|
|
Term
| amino acids that enter mainsteram metabolism by way of succinyl CoA |
|
Definition
-methionine
-isoleucine
-valine |
|
|
Term
| depiction of succinyl CoA formation from methionine, isoleucine, and valine |
|
Definition
|
|
Term
| the branched chain amino acids that enter mainstream metabolism |
|
Definition
-leucine
-isoleucine
-valine |
|
|
Term
| branched-chain α-ketoacid dehydrogenase complex |
|
Definition
| catalyzes the oxidative decatboxylation of α-ketoisocaproate into isovaletyl CoA |
|
|
Term
| depiction of leucine being converted into isovaleryl CoA |
|
Definition
|
|
Term
| depiction of the function of the branched-chain α-ketoacid dehydrogenase complex |
|
Definition
|
|
Term
| depiction of isovaleryl CoA being converted into β-methylglutaconyl CoA |
|
Definition
|
|
Term
| depiction of β-methylglutaconyl CoA being converted into acetyl CoA and acetoacetate |
|
Definition
|
|
Term
| overall conversion of leucine into acetyl CoA and acetoacetate |
|
Definition
| make a composite picture of the 3 rxn sequences on p. 563 |
|
|
Term
| what is used to break the aromatic ring in aromatic amino acids? |
|
Definition
|
|
Term
| phenylalanine hydroxylase |
|
Definition
| catalyzes the hydroxylation of phenylalanine to tyrosine |
|
|
Term
| depiction of the function of phenylalanine hydroxylase |
|
Definition
|
|
Term
| monooxygenase or mixed-function oxygenase |
|
Definition
| oxygenase that makes 1 O atom of O2 go to the product and the other go to H2O
example: phenylalanine hydroxylase |
|
|
Term
| net rxn for the hydroxylation of phenylalanine to tyrosine |
|
Definition
| phenylalanine + H2O + NADH + H+ --> tyrosine + NAD+ + H2O |
|
|
Term
| depiction of phenylalanine and tyrosine degradation |
|
Definition
|
|
Term
| the end products of phenylalanine and tyrosine degradation |
|
Definition
| acetoacetate and fumarate |
|
|
Term
| nearly all cleavages of aromatic rings in biological systems are catalyzed by... |
|
Definition
|
|
Term
|
Definition
| enzyme that incorporates both O atoms into the product |
|
|
Term
| depiction of tryptophan degradation |
|
Definition
|
|
Term
| end products of tryptophan degradation |
|
Definition
|
|
Term
| the end product of methionine degradation |
|
Definition
|
|
Term
| depiction of methionine metabolism |
|
Definition
|
|
