Metabolism | Regulation of Glycolysis

I'm engineers in this video we're going to go over the regulation of glycolysis so we already went into a lot of detail on basically all the glycolytic pathway right we went over every single substrate every single enzyme and we went over a couple just you know correlations clinical correlations as well as we did a little kind of tally here of all the actual end results of glycolysis and we talked about all the different types of glut transporters in this video we're just going to hone in on three special enzymes what are those special enzymes I mentioned them here in the black steps right these black arrows this one here hexokinase this one here phosphofructokinase one and this last one down here pyruvate kinase these are the enzymes that we're going to be focusing on in this video and the reason why we have to focus on these is because they are highly regulated in other words there are certain types of substrates or hormones that are influencing these enzymes to control this glycolytic pathway okay let's get into it okay so we got each enzyme here that the three enzymes this one right here the first one it was the one that was converting glucose what was this molecule in our starting substrate glucose so here's our glucose and what could we do what did this enzyme do this hexokinase our gluco kinase it converted glucose into glucose 6-phosphate so again what is this molecule called it's called glucose 6-phosphate then there was this next one which we had was fructose 6-phosphate then after what happened and went into fructose 1 6 bisphosphate then into dihydroxyacetone phosphate glyceraldehyde 3-phosphate 1 3 bisphosphoglycerate 3 phosphoglycerate 2 phosphoglycerate pep and then pyruvate and the same reaction is occurring over here but I told you DHAP can't get cumbered into 1/3 BPG he has to first be converted into glycerol 3-phosphate then 1/3 BPG then 3 phosphoglycerate to floss flow glycerin pep and then eventually pyruvate okay and if you guys remember there was a very important step where we were producing ATP and that step was going to be right here we were producing to it we were actually producing ATP in this step if we technically consider it and we were producing ATP in this step right here we were also producing an ATP in this step here and we were producing an ATP in this step here and if you guys also remember we were generating in this step right here to actually if we think about it if we keep it consistent and nad+ to an NADH right here mmm this marker stinks and then over here in a different color same thing though NAD+ to NADH boat shouldn't be there it should be at glyceraldehyde-3-phosphate so we should have that NAD+ being convert into NADH here at the go throughout our 3 phosphate set so NAD+ to NADH and to keep it consistent here all nice colors and maybe positive to NAD+ NADH sorry and this stuff here okay so out of this if you guys remember we generated one two three four ATP's but that was gross we generated two NADH s and we put two ATP into the system n ATP here and an ATP here okay so we get that point now right now we're going to focus on these enzymes look at him he's scared because he doesn't know what's going to happen what's going to happen to this guy what is the name of this enzyme there's two different enzymes let's say the digital is the one that it's in almost all body cells so in other words this is hexo kinase and if you guys want to be particularly you could say hexokinase type 2 if you want to okay we could put that if you want and put type two it's kind of a little bit more special for the muscles but in general you just call it hex with high knees the other one that's only found in the liver is somewhere else this enzyme is freely in the cytoplasm this other enzyme has to be housed somewhere in the nucleus and again what is this enzyme call it's called gluco kinase now this gluco kinase is always in the liver until it's actually brought out by some type of stimulus and we'll talk about that and then HEC so kindness is just kind of freely circulating okay so what's the stimulus for hexyl kinase now I got to talk about a term which because we're going to I'm talking about regulation but I can't just go in there and say this is what this guy is doing this is what this guy is doing there's two types of regulation allosteric in hormonal so what do I mean by that okay we talked about an enzyme an enzyme has an overall three-dimensional shape so when it functions it has to have a special type of active site in other words right so let's say here's my enzyme little Pacman style okay that's his active site but let's say that on the back of him he has a little pocket okay that's his allosteric site so that's his active site that's where he's dealing with the substrate let's say I've put in here a substrate okay there's the substrate that he's going to react with on the other side maybe there's a little pocket where certain things will call it factor X combined on to what is that going to do to him it's going to contort his overall three-dimensional structure when it contorts his overall 3-dimensional structure it might change the activity of the active site and we there enhance it or might inhibit it so the whole purpose is that these molecules allosteric regulators are binding on to the allosteric site other than the active site and controlling its overall three-dimensional shape which can either activate it or deactivate it hormonal is going to be more with the terms of phosphorylation and dephosphorylation and we'll talk about that with insulin and glucagon this video okay so hexokinase it's easy to think about this when you guys think about glycolysis okay if I want this enzyme to work what is he doing he's converting glucose into glucose 6-phosphate so if I have a lot of glucose I'm going to want to convert it into him that would be a stimulator pretty unique look glucose is right here your what is he gonna do he's going to stimulate this enzyme not bad okay well what happens how do I know when this enzyme can say okay I need to stop I can't convert any more glucose to glucose 6-phosphate when you're forming a lot of glucose 6-phosphate huh why don't I just have this guy come in and inhibit him that's it it's so easy right it's not that bad because all we have is glucose is stimulating this enzyme and glucose 6-phosphate is inhibiting it okay now next step in the liver it's a little bit different but the stimulus is still the same because Google kindness is in the nucleus until look what happens glucose is just like yeah buddy let me let me get you out of there so glucose comes in here and what if you do he stimulates this enzyme if you stimulate this enzyme were systems I'm going to go it's going to come out here and when it comes out here what is it going to do it's going to stimulate this step converting glucose into glucose 6-phosphate but whenever he's done he's like I don't want to do this anymore I want to go back to my home there has to be someone that can actually inhibit him and put him back into the nucleus who's going to do that fructose 6-phosphate so fructose 6-phosphate does the opposite so glucose brings glucokinase out of the nucleus and works in this step this first step fructose 6-phosphate inhibit this enzyme and shoves him back in the nucleus so here's our fructose 6-phosphate it's going to inhibit this enzyme put them back in the nucleus okay now that's the allosteric regulation not so bad what about the hormonal regulation a little bit different okay there's two hormones that I want to talk about one is going to be insulin and the other one is going to be glucagon okay let's talk about insulin first insulin is really special insulin actually going to be released to win when do you release insulin you release insulin when your blood glucose levels are high okay from your pancreatic beta-cells whenever you have high blood glucose levels usually greater than about 130 milligrams per deal it usually kicks in insulin is going to try to do what break that glucose make ATP do something with it so what's going to happen is insulin does a special thing it actually goes into the nucleus over there and it can stimulate the synthesis of more glucokinase and more hexokinase isn't that awesome so when you need more of these enzymes to have more glycolysis instils like I got you bro what does he do he goes into the actual nucleus activates genes to make more glucokinase and more hexokinase so their actual amount increases not just necessarily their activity because that can increase also but their amount is increasing okay their abundance E is increasing okay so now what about the cut what about the contrast of that what about someone who's actually going to inhibit these enzymes that would be the job of glucagon so glucagon is released I like to think about it like this one of my professors told me whenever glucose is gone okay so goo gone is whenever you have low blood glucose levels or like to think about whenever glucose is gone in other words it's low now the whole point is don't keep breaking down glucose put the glucose into the bloodstream so inhibit these enzymes from working so I can get glucose into the blood so what is this guy going to do this guy is going to inhibit these enzymes so he's going to come over and he's going to do what he's going to inhibit this enzyme and then again to inhibit this enzyme okay let's go ahead and recap that real quick hexokinase and glucokinase are both stimulated by glucose hexokinase is inhibited by fruit - I'm sorry glucose 6-phosphate so again EXO kindness is inhibited by glucose-6-phosphate and this is allosteric glucokinase is stimulated by glucose to come out of the nucleus and work in this first step fructose 6-phosphate inhibits the Google Heinie's and puts him back into the nucleus to not control glycolysis and then hormonal e insulin is stimulating the synthesis of more hexokinase and more glucokinase for more glycolysis because there's high glucose levels break that crap down so don't you don't have it in the blood anymore glucagon is released whenever your glucose levels are low we don't want glycolysis to occur we want the opposite action tracker gluconeogenesis and we'll talk about that so we can make glucose and contribute to the blood glucose levels so usually whenever the blood glucose levels gets below about 70 milligrams for he'll he might kick in okay that's our first enzyme not so bad here's where your death awaits you okay now this enzyme is a little these two enzymes are a little crazy and this one is also a little bit tough but we're going to do the best we can here ready this first enzyme you guys remember we talked about them it's called phospho fructose kinase 1 names like ah y1 because there's a phospholipid kinase to that what to talk about ok so now what is this enzyme doing okay this enzyme is actually remember he's adding ATP in this step so if you guys think about if we were to really be specific what's actually coming out of this first step that we talked about adp right but we already knew that from the original video that we talked about it and then in this step to make it leaving a little bit more clear ATP is coming in and adp is coming out so phosphofructokinase is phosphorylating fructose 6-phosphate to convert them into fructose 1 6 bisphosphate this is probably one of the most highly regulated steps within throughout glycolysis okay so it's a very important one that we have to get a little complex but we can do it ok first thing one thing to think about I like to think about is as a result of that pyruvate if you guys remember we said pyruvate will eventually get converted into acetyl co a they'll then go into the actual Krebs cycle it will go to the electron transport chain and make ATP whenever you're making too much ATP that's going to tell these enzymes hey I'm already producing a lot of energy there's a large amount of energy supply within the body don't keep doing glycolysis because our cells can only store so much cellular ATP so what is that going to do then well ATP can come over here and he can allosteric lee inhibit this enzyme so what can ATP do it can inhibit this enzyme what else can actually inhibit it there's a krebs cycle intermediate Krebs cycle intermediates are the first ones starting substrate for the actual Krebs cycle and it's called citrate citrate basically tells you ok there's a lot of krebs cycle activity going on if there's a lot of krebs cycle activity going on Oh this shouldn't be stimulate they should inhibit trade is an inhibitor because that's actually showing that there's a lot of energy production to be occurring there's a lot of Krebs cycle activity occurring if there's a lot of Krebs cycle activity occurring I'm going to make a lot of nadh is a lot of fadh2s and if i make too much of those i'm going to make a lot of ATP so these two are kind of intertwined or interconnected and concept right so too much cellular ATP means that there's a lot of ATP formation occurring we don't need to make anymore a lot of citrate means that there's a lot of Krebs cycle activity which will actually lead to the actual formation of a lot of ATP so these two are kind of working conjunction those are inhibiting this enzyme allosteric ly then what would actually be the opposite you know ATP whatever we're utilizing it for pumps or for metabolic issues or for transport mechanisms whatever maybe you know ATP is actually getting broken down by hydrolysis into ADP and an inorganic velocity right so whenever you have a lot of ATP breakdown what happens to the concentration of your ATP it goes down and if you break a lot of us down you're going to form a lot of ADP well when the body we don't really say low ATP we say high ADP because that's an indicator that there's not a lot of ATP in the cell and we need to make more so what do you think that would be what did I be a stimulus or inhibitor that would be a stimulus all right so high amounts of ADP would actually do what to this enzyme it would stimulate him because then it's letting this enzyme know hey there's not a lot of ATP being made you need to stimulate this process so that I can make more ATP because again this enzyme is stimulating this step but if you inhibit him he will not stimulate this step if you stimulated he will stimulate this stuff it's pretty simple right alright now comes the complicated part that's where I need you guys to kind of bear with me here I'm going to raise this and get this out of the way though because we're going to need this room okay here we go hang in there with you guys okay this fructose 6-phosphate I'm going to bring them over here for a second so let's bring fructose 6-phosphate over here but again I'm just going to denote it you guys are going to see it as f6p okay what happens is a small amount of fructose 6-phosphate goes through this other pathway so I'm going to show it coming over here look I'm going to bring this fructose 6-phosphate coming right there okay now generally the fructose 6-phosphate can go through this pathway a good good large amount of it goes through this pathway converting fructose 6-phosphate to fructose 1 6 bisphosphate but a tiny amount a very small amount here will even put that small amount can divert into this other pathway where it'll react with this enzyme complex this is a hetero nuclear or by nuclear complex basically it's two enzymes kind of joined together to compact as one whole enzyme so look at this I have two components of it two components of this enzyme one is a phosphofructokinase 2 component of the same time so for the by nuclear enzyme the other one is fructose 1 6 bisphosphate 802 6 fructose two six bits phosphatase okay again this whole by nuclear complex is actually consisting of Philosopher's Co kinase 2 and fructose 2 6 dispositive it's an entire enzyme in itself with two different types of domains what's going to happen is I can take this fructose 6-phosphate and in the presence of phosphofructokinase 2 I can convert it into fructose 2 6 bisphosphate fructose 2 6 bisphosphate okay when I'm making this fructose 2 6 bisphosphate this is one off let's actually highlight how because this is an important one this is the most powerful regulator of phosphofructokinase 1 because guess what this guy can do he can come over here and look what he can do he can bind on to the allosteric site of this enzyme and do what to it stimulate this enzyme if you stimulate this enzyme what's going to happen it's going to become active if it becomes active what happens it's going to convert more fructose 6-phosphate into fructose 1 6 bisphosphate to be able to make more ATP so this is a very very let's actually put it under it most powerful regulator of PF k1 okay now like always though there has to be a portion that can convert them back into fructose 6-phosphate so there's another component of this enzyme which converts him back into fructose 6-phosphate and who does that fructose to six bits velocities now these enzymes are also highly regulated but primarily by hormones your insulin and glucagon let's bring those guys back in so here's our insulin here's our glucagon whenever our glucose levels are high we are going to want to do glycolysis okay well if I want to do glycolysis that means I'd want to stimulate this enzyme because this enzyme converts fructose 6-phosphate into fructose to 6 bisphosphate which stimulates this enzyme which stimulates this conversion and that'll eventually lead to breaking down the glucose to make ATP okay but I would want to do what to this enzyme inhibit this enzyme before we do that we need to see what glucagon does move on does the exact opposite glucagon will inhibit this enzyme because then what if this enzyme if Gujarat inhibits this enzyme it can convert fructose 6-phosphate into fructose to 6 bisphosphate that will no longer be present to stimulate this enzyme also if you guys watch the gluconeogenesis video fructose to 6 bisphosphate when his concentration decreases he actually stimulates the fructose 1 6 bisphosphate which eventually converts that into glucose now this enzyme this I'm sorry glucagon what should he be doing to these two like I already told you he's going to want to inhibit this part how is he going to inhibit it what glucagon does is he phosphorylates both of these guys so he comes over here and puts a phosphate on this guy and comes over here and puts a phosphate on this guy's perm look he's got a perm okay get his Jheri curls now what's going to happen is Google gon is going to phosphorylate these two by nuclear complexes when he phosphorylate this guy it inhibits him okay when he phosphorylate this guy what does it do it stimulates him okay because why because then we would break down this fructose to 6 bisphosphate into fructose 6-phosphate his concentration decreases he gets inhibited and the opposite reaction with fructose 1 6 bisphosphate becomes stimulated holy goodness that was a lot right now insulin all he is going to do is he's like oh man I want this guy to be stimulated and I want him to be inhibited well phosphates stimulate him phosphates inhibit him okay guess what I'm gonna do insulin is pretty smart you know what he does he comes over here and rips off that phosphate there and guess what LCOS he rips the phosphates off over here so look he comes over here also and rips those phosphates off so now these phosphates are going to be lost if you lose the phosphates off of this one so now the phosphates are all gone so that you get rid of this phosphate get rid of this phosphate get rid of this phosphate this is no longer going to be under an abyssion it's going to be stimulated oh nice then if I remove the philosophes off of this guy well phosphates normally stimulate him but I'm getting rid of them so all of these phosphates are going to be gone what is this going to do to him it's going to inhibit this enzyme how is that going to help because if I stimulate this enzyme he'll convert fructose 6-phosphate into fructose to 6 bisphosphate which will stimulate this Sainz I'm and drive this reaction holy goodness I hope all of that made sense guys okay let's keep plugging along so that made sense we're going to move on to the last and final step here pyruvate kinase so this last one is a pretty cool one and this is called pyruvate Tiny's now this one's pretty regulated they're also very very important enzyme so pyruvic kindness if you guys remember was doing what he was generating ATP he was plucking off the philosophes off of the pep and adding it onto ADP to make ATP when he's also a very very important enzyme because he's gonna he's not going to be reversible so how do we reverse this okay what can we do to inhibit this guy so let's say that these are the inhibitor portion okay whatever let's say that we actually are making too much ATP same thing usually can always remember that there's too much ATP that's generally going to inhibit this enzyme so if I have too much ATP what is that going to do to this enzyme it's going to inhibit it so if ATP is actually high what does that mean that means that we're having a lot of Sailor activity a lot of energy production too much energy production we want to shut that down say hey we can make we can do something with it later now another thing if there's too much ATP that will inhibit it but you know what else will actually inhibit it a lot of long-chain fatty acyl Koei's what is that indicating this is indicating that there's a lot of beta oxidation okay so now these long-chain fatty acid Koei's again what are they coming from where you're going - you'll see whenever we go over the fatty acid metabolism but it's going to undergo a process called beta oxidation the overall point of this is that you're going to make a lot of acetyl co ways when you make a lot of acetyl co is what's going to happen is you're going to have a lot of Krebs cycle activity a lot of NADH is a lot of fadh2 and a lot of ATP so it's basically indicating that there's a lot of energy supply within the body okay and now the same thing if you're producing a lot of if you're oxidizing a lot of long-chain fatty acids what I say you're going to develop a lot of acetyl co a so if you make a lot of acetyl co a there's too much acetyl co a you're going to want to inhibit this step because they're just going to have more and eventually that'll go to forming ketone bodies or to go to form cholesterol at all depends and it could be you know sometimes it could be disastrous sometimes it's you know helpful but it all depends a guy I guess on the body's needs so again too much ATP too much long-chain fatty acids from beta oxidation can inhibit this step and too much acetyl co a can also inhibit this step and that should make sense because these are all indicators of too much energy production now another thing these are the allosteric inhibitors what would be a hormonal inhibitor well I'll think about it glucagon doesn't want the glucose to continue to get broken down because there's not much glucose in the blood so glucagon would want to oppose this action right so he would want to he won't inhibit this enzyme so glucagon is going to do what it's going to inhibit this enzyme but you guys already know how what is it going to do it's going to phosphorylate the enzyme and you know when it phosphorylates this enzyme and inhibits it okay next thing what is going to stimulate this implant so let's think about this logically the first one that you should automatically should just go to your brain is think about what happens whenever you're going to have the hormone think about the hormone what is that hormone that we mentioned up there that would actually stimulate the step because the blood glucose levels are too high we want to break some of that glucose down insulin insulin is going to do that and you know how insulin is going to do this I mentioned it before insulin was going to we talked about this with hexokinase and glucokinase remember was increasing the expression of those guys he can also increase the synthesis a little bit of the pyruvate kinase that's pretty cool right so you can also help the synthesis of fossil fruto kinase one so if you think about all the glycolytic enzymes insulin can help to synthesize the primary ones which are synthesized in the largest amount is hexokinase and glucokinase but you can he can also synthesize pfk one and can also set the size pyruvate kinase but if you also want to think about what else you can do what else could he do guys if glucagon is phosphorylating this puppy what would he do he's going to be phosphorylated right by activating phosphoprotein phosphatases what you're going to remove the phosphate off of it and this will stimulate this implies the last thing this is the probably one that you guys wouldn't expect I'm going to write it down so that you guys can be like what doc I don't understand why fructose 1 6 Bin's philosophy this is going to be a stimulator now this is an example I'm going to write it down of what's called a feed-forward forward can smell it for a second I'm sorry feed-forward reaction so we're the feed forward reaction mean okay well this enzymes all the way down here where's fructose 1 6 bisphosphate it's all the way up here this guy is going to be producing maybe large amounts what he's going to do is he's going to come down here and tell pyruvate kinase hey buddy get ready because you're getting a shipment of a whole bunch of all of us so you better be ready and your activity better be increased because we need you to be able to catalyze the conversion of pep into pyruvate so that we can go into making ATP ok so just remember that fructose 1 6 bisphosphate is an example of a feed-forward reaction he's coming before the reaction but he's telling this enzyme to get ready because you're going to need to increase your activity to convert me and eventually into pyruvate alright last but not least I wanted to provide a little clinical correlation nothing crazy but I told you a little bit about this enzyme I didn't mention a significant amount about him but it was called glyceraldehyde-3-phosphate dehydrogenase right and I told you that not only was he helping to generate nadh --is right in this step and the steps to same enzyme but also he was adding a phosphate into this reaction here's the problem the glycerol 3-phosphate dehydrogenase and the pyruvate kinase are susceptible to a similar type of molecule that can actually bind in the place of phosphate on this enzyme that dangerous molecule is called arsenate so arsenate arsenate can actually bind into that pocket that pocket where the phosphate cells and then buying into it and inhibit the fossil from being added if you inhibit the fossil from being addict and this reaction continue to occur no so eventually you don't form pyruvate that's the deadly part of arsenic within this part here ok and then the same thing arsenate can also allosteric inhibitors enzyme also and this can cause disastrous effects because there's nothing like these types of effects this is going to be a very very type of dangerous type of inhibition where these enzymes won't be able to properly operate all right engineers we did a lot in this video we covered the regulation of all of the actual significant enzymes throughout this process hormonal and allosteric we did a quick recap of the glycolysis pathway we understand what we made from it and I hope that you guys really did enjoy it I hope it all made sense I hope it came together if it did please hit that like button subscribe put a comment down in the comment section we look forward to being able to hear from you guys and we want to really help you guys out iron innards until next time

Channel: Ninja Nerd

Views: 312,103

Rating: 4.983386 out of 5

Keywords: regulation of glycolysis, metabolism

Id: xoqyF6DJZ-Y

Length: 29min 17sec (1757 seconds)

Published: Tue Jun 13 2017