Metabolism Exam 3 Here we go Amino Acid Metabolism Amino acids can either be synthesized in the body endogenous or obtained through the diet Once you get them into the body they undergo anabolism in order to be synthesized for a variety of different bodily functions Some significant functions are o Hormones insulin and glucagon o Immunoproteins antibodies o Biogenic amines neurotransmitters Dopamine epinephrine and norepinephrine Amino Acid Classification by structure net charge and essentiality o Structure Take a look at your online notes while I am explaining these Alipathic This means non polar hydrophobic This group of has side chains off of the base structure that consists of Carbon Hydrogen only molecules There is no net charge on the structures Hydroxylic This literally means a side chain with OH group in it They are polar and can be somewhat hydrophilic with no net charge Sulfur containing These are the same as above but with a S group and not an OH group Carboxyl or Amide These are side chains that have either a COO or amide group These are hydrophilic amino acids These tend to either have a net charge carboxyl or no net amide charge Basic groups These amino acids basically have another net charge from an NH3 somewhere in the side chain Aromatic These are simple have an aromatic ring The only significant one is Tyrosine Tyrosine has an OH group but it was derived from Phenylalanine so it takes priority There is no net charge Imino Acid There is only one of these and it is Proline Imino literally means have the N from the basic structure within the side chain as you will see in the picture o Net Charge I mentioned how some of each structures have what net charge but this is just to clarify a little and show what she said during class Zwitterions have none because the only charges is the from the amino group and from the carboxyl on the basic structure they cancel each other out So the Alipathic amino acids are great examples Polarity This is the tendency for amino acids to interact with water at physiological pH Can be classified as polar or non polar depending on the side chain I gave some examples when explaining structures o Essentiality Non essential Endogenous Alanine Asparagine Aspartic Acid Glutamic acid Essential These are the ones that must be obtained from diet Conditionally essential Usually not essential illness or stress can cause the body to convert non essential to essential o Met or Ser Cys o Phe Tyr o Glutamate Proline o Glutamine or Glutamate Arginine o Glutamate or Ammonia Glutamine Threonine Histidine or Lysine cannot undergo transamination o Sources of Protein Exogenous from food sources Animal products Anything except the fats These are the best sources because they are complete Plant products grains legumes and vegetables These are incomplete so you have to eat all types to receive all amino acids Endogenous from the body Desquamated mucosal cells body produces 50g day Digestive enzymes glycoproteins Body produces 17g day o Transamination As I was saying before certain amino acids do not undergo this It is the formation or non essential amino acids from essential amino acids or to create another essential amino acids from another essential amino acid It is usually the first step in any amino acid formation Catalyzed by aminotransferase enzymes which can be increased by cortisol Requires B6 as a coenzyme PLP pyidoxal phosphate o PLP stimulates glucagon for protein breakdown then the body can stress and cause cortisol to take the broken down protein amino acids and for glucose by cortisol Synthesis increases in the liver in response to glucocorticoids Increased serum levels suggests liver damage o Alpha Keto Acid vs Amino Acid On the alpha Carbon the Carbon next to the COOH there is a ketone on the Carbon to Keto Acid and a NH2 group on the alpha carbon of amino acid o Ainotransferase reaction This is the conversion of an amino acid to a keto acid Aminotransferase is the major enzyme PLP is the coenzyme Some examples Alanine can convert alpha keto acid alpha amino acid by alanine amino transferase ALT o This causes the Alanine Pyruvate when transferring the amino acid o Presesnt in the liver Aspartate can convert alpha ketoacid to alpha amino acid by Aspartate amino transferase AST o This causes the Aspartate OAA during the process OAA can then enter the Krebb s cycle o Presesnt in the heart but more in the liver o Ammonia NH3 Metabolism This is the conversion of NH3 to make it nontoxic organic linkages There are 3 ways the liver can do this Reductive amination Production of amides Glutamine and Asparagine Formation of carbamyl PO4 for urea synthesis and pyrimidine synthesis o Glutamate Metabolism Aminotransferase transamination Oxidative deamination Glutatmate is the only amino acid to undergo the oxidative deamination This is glutamate alpha ketoglutarate o Glutatmate Dehydrogenase reversible o Hydrolysis H2O in o NH3 out to the Urea cycle o NAD NADH H Reductive amination The reverse of above so alphaketoglutarate Glutamate o Same enzyme o NH4 in to form organic non toxic form NEAA o H20 out o NADPH H NADP Formation of Glutamine Glutamate Gutamine Glutamine is another way to get NH3 to a non toxic form and is important for hormones in the enterocytes of muscles Glutamine Amide group so it has 2 amine groups Glutamine Synthetase irreversible step ATP ADP NH4 in and H2O out o The Urea Cycle Understand the Urea Cycle chart Arininosuccinate Synthetase Major rate limiting enzyme The purpose for this cycle is converting NH3 to a non toxic excretory product urea Urea the major nitrogen source in urine The process is located in the liver NH3 can be mad in the body by chemical reactions food and bacteria breakdown The disposal of ammonia can be done through Kidney excreted through the urine o 25 may be excreted into the intestinal lumen because of bacteria degredation Regulation o Low protein diets This causes you to have less excretion because you have less protein synthesis meaning less Nitrogen o Increased metabolic acidosis Causes more Urea disposal o Increased Starvation Causes increased Urea disposal because your body is relying on glucagon which facilitates in protein breakdown o Hepatic Amino Acid Metabolism This mostly happens in the liver and some in the brain Catabolism of aromatic amino acids Phenylalanine tyrosine conditional Essential Amino Acid and tryptophan Phenylalanine Tyrosine adding an OH group to the aromatic ring Phenylalanine
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