Protein catabolism lightboard video

Protein catabolism lightboard video



we're going to look a little bit amino acid catabolism so you know that amino acids are the monomers that comprise proteins so our proteins are large macromolecules and we break them down as a macronutrient to get energy so we oxidize their proteins in order to get the energy that we need in the form of ATP we also use that amino acids that are produced from our proteins that they're made to build new proteins now the interesting thing about amino acids is that we can't store them so our proteins and amino acids they're not like fats where we can store them as th es in the body it's not like glucose that we can store it as glycogen we don't have a way to store amino acids so our intake of amino acids that we need as building blocks for new proteins either comes from the food we take in and our diet or from the breakdown of proteins into amino acids that can then be used to build new proteins so what we're going to look at here is a little bit about what happens to our amino acids so our amino acids are comprised of two parts we have an alpha amino group so remember that our amino acids have a nitrogen portion and then they also have a carbon skeleton now the body is quite economical so if we have an excess of amino acids remember we can't store them for when they're needed so we need to break those amino acids down so the carbon skeleton can get reused in other places in metabolism so it can get fully oxidized to carbon dioxide plus water we can have precursors for glucose we can have some amino acid so depending on what they're our group is can be four acetyl co a and others for ketone bodies so depending on the type of amino acid it depends on where that carbon skeleton might end up it has different faiths and then for nitrogen portion that is removed and ultimately in the urea cycle that nitrogen is excreted from the body because it's not needed so here we have our urea cycles so this is a way that the body can eliminate the extra nitrogen that's not needed you can see here I've written two steps that are involved in removing the Alpha amino group from our amino acids so that's any amino acid that's to be degraded the first step is transamination so that's where we take the Alfre me know group from an amino acid and it's transferred to an alpha keto acid now what does that mean that means that our amino acid becomes an alpha keto acid and our alpha keto acid becomes an amino acid and that process at first seems a little bit redundant but our predominant alpha keto acid is alpha ketoglutarate which you might remember is an intermediate in the TCA cycle so I most of the time or predominantly what we're getting is an hour our amino acid to be degraded transfers itself for amino group to alpha ketoglutarate which gives us glutamate most of the time as our new amino acid that's formed and we get a new alpha Oh acid and this reaction is carried out by an enzyme and that enzyme is known as an amino transferase just easy to remember because we're transferring an amino group or a trans RNA is so you can see a transaminase is involved in the transamination reaction the second reaction occurs with this glutamate that we have and that is carried out by glutamate dehydrogenase so again as the name suggests glutamate dehydrogenase it acts on glutamate it's a dehydrogenase so we're thinking of oxidation and reduction reactions this is carried out in the mitochondria and it uses it's interesting because it uses nad plus or in a DP plus as its cofactor so it's interesting it and that it can use either of those and obviously these are reduced in the process as a result of that we get ammonium ion being produced and that is what enters our urea cycle so that's one of our nitrogens that then goes into the urea cycle and ultimately ends up being excreted in the urine molecule

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