Protein and Amino Acid Met Flashcards
Identify biological roles for amino acids
Can we use amino acids for energy (via oxidation)? Under what conditions might this happen?
What are reasons that excess amino acids can be challenging for mammalian metabolism?
briefly describe the digestive enzyme for proteins: proteases
briefly describe the digestive enzyme for proteins: peptidases
what is a zymogen?
Removal of the amino group is the first step: how are -ketoglutarate and glutamine involved?
Distinguish between oxidative deamination and transamination
Why can’t ammomiun (NH4+) travel in the bloodstream? How are NH4+ equivalents carried (provide different examples)?
what are the reactions of the glucose-alanine cycle?
where are the reactions in the glucose-alanine cycle primarily located?
what is the physiological function of the glucose-alanine cycle?
What are some different forms of nitrogen excreted by different organisms?
What are transaminase enzymes? What is the reaction catalyzed by alanine transaminase?
What are the steps of the urea cycle (know the reactions and the enzymes)?
How does –NH3 enter the mitochondria and become ammonia (there is more than one mechanism)?
How is free ammonia captured in the mitochondrial matrix by carbamoyl phosphate synthase I?
How does the nitrogen in the urea cycle leave the mitochondria (two ways)?
How does nitrogen enter the urea cycle (two ways)?
How does urea leave the cycle, and what happens to the final product(s)?
Why do the urea cycle and the citric acid cycle make up the “Krebs Bicycle” (how are they connected)?
Describe how the urea cycle may be regulated.
Describe ketogenic vs. glucogenic amino acids.
-ketogenic: metabolizes products into ketone bodies; leucine and lysine
-glucogenic: AA broken down into products for gluconeogenesis
What are some possible fates of carbon skeletons resulting from amino acid degradation (can they intersect with pathways we have already studied)?
What happens to amino acids that can yield carbon skeletons containing 2 carbons?
-make ketone bodies
-can be turned into acetyl Co-A
What happens to amino acids that can yield carbon skeletons containing 3 carbons?
-can be turned into pyruvate to be used in gluconeogenesis
-ex. threonine can be cleaved into glycine and acetaldehyde
What happens to amino acids that can yield carbon skeletons containing 4 carbons?
-can be turned into oxaloacetate to be used for gluconeogenesis via TCA
What happens to amino acids that can yield carbon skeletons containing 5 carbons?
-become a-ketoglutarate
-ex. histidine, ornithine, glutamate
How is glycine degraded? Follow it through the pathways of central metabolism
-glycine comes from the cleavage of threonine
-glycine can become other AA to become pyruvate
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What can happen if genetic defects affect amino acid catabolism—find one example.
brief overview of the processing of xenobiotic compounds
-xenobiotics: molecules the body sees as foreign
-not naturally produced, must be eliminated
-cleaved into smaller fragments
-made more hydrophilic for elimination
What happens in Phase I?
-foreign molecule oxidized and cleaved
-become more hydrophilic
-sometimes metabolites are active
-add a handle for attack
-enzymes: esterases, oxidases, dehydrogenases
What happens in Phase II?
-conjugation to larger molecules (ex. glutathione) to increase solubility
-attacks handle on molecule
-molecule further inactivated
-enzymes: transferases
What are cytochrome P450 enzymes?
-responsible for catalyzing many of the Phase 1 reactions
-oxidatively modify substrate molecules using NADPH and O2
-found in inner mito mem and ER
What are amine monooxygenases?
-monoamine oxidases
-enzyme has FAD fixed in it for redox
-deactivate neurotransmitters
-convert amine to aldehyde
-two isoforms: MAO-A, MAO-B
Which AA’s can become Succinyl CoA?
-Met
-Val
-Ile
Which AA can become acetyl CoA, fumarate and acetoacetate?
-Leu
-Lys
-Tyr
-Phe
-Trp
How does monoamine oxidase link to central metabolism?
-it produces ammonium which can be used in the urea cycle
Differentiate between glucuronic acid and glutathione
-glucuronic acid: ox form of glucose (has carb acid); uses UDP-glucuronic acid
-glutathione: tripeptide of glycine, cysteine and glutamate
-uses glutathione-S-transferase
