Metabolism | Pentose Phosphate Pathway

I'm engineers in this video we're going to talk about the pentose phosphate pathway now the pentose phosphate pathway is a very very important pathway and what's going to happen is we're going to see exactly how important it is throughout the series of this out to Syria this video but it's going to be extremely extremely important for synthesis reactions for example synthesizing neurotransmitter synthesizing lipids cholesterol synthesizing nucleotides you know synthesizing many many different types of things so we're going to see that this is a very very important step also it's very very important for free radical reactions so we'll see exactly how all this is happening now if you guys remember let's say I bring glucose into the cell alright so I bring glucose I'm going to represent with a G I'll bring this into the cell but you know that it can't just pass through the cell membrane you know it has to have a special type of blood transport right so let's just say that this is a liver cell if it's a liver cell you know that the liver cell has glut to transporter so let's say that this is a liver cell and this is having glut two transports but whatever okay we bring this glucose into the cell once we bring this glucose into the cell so now let's say here's our glucose if you guys remember glucose can be acted on by a special enzyme present with inside of the liver and it's a special one right that enzyme is called gluco kinase so the enzyme here is called gluco kinase now glucokinase is doing what it's putting a phosphate on the sixth carbon of glucose so let's now do that let's actually represent that so now what's going to happen we're going to have glucose here but if you guys remember in this step what are we going to do we're going to take ATP and convert it into adp because this google kinase is going to take and transfer one of the phosphates off of the ATP onto the glucose so now on the six carbon of glucose i have a phosphate group this is my glucose 6-phosphate so now what am I going to do with this glucose 6-phosphate well there's two things I can do with them one thing is I could run this puppy through glycolysis right I could run this sucker right through glyco so let's run it through glycolysis really really quickly ready so what are some of the steps of glycolysis you guys remember I can take glucose 6-phosphate convert it into fructose 6-phosphate then if you guys remember from that fructose 6-phosphate I can and then do what I can convert that into fructose 1 6 bisphosphate so in this step I can convert fructose 6-phosphate into fructose 1 6 bisphosphate but remember this step required ATP so ATP is being utilized in this step and we're converting this molecule now into fructose 1 6 bisphosphate okay 1 6 bisphosphate then what happened if you guys remember the fructose 1 6 bisphosphate split by an aldolase enzyme right and got converted into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate and then you know that these guys can isomerize between each other right then the glycerine i3 phosphate did what it went through a series of reactions like what it went to 1 comma 3 b PG 2 what then it actually went to 3 phosphoglycerate to 2-phosphoglycerate to fossil in all pyruvate to pyruvate and it just keeps going and going and going right but throughout a series of these steps you guys remember that you generate what you generate an ATP you take an ADP here and you make ATP but this happens twice because when you split fructose 1 6 bisphosphate you get one of this guy and one of this guy but most of it funnels into this guy so technically you have two of him two of him two of him two of him two of him and two of them so technically I generate two ATP in this step another thing is right here going from 1 3 bisphosphoglycerate bisphosphoglycerate to 3 phosphoglycerate i also generate another ATP but again two of them because this pathway occurs twice so in general how many ATP that I produce out of all of this I produced 4 ATP right but that was the gross ATP because I used 2 ATP in the beginning of the process I actually only netted really 2 ATP so I only really netted 2 ATP ok now this is going to be important that we understand that this glucose 6-phosphate can go through this pathway just depends upon the body's needs now we're going to take this puppy and run it through the pentose phosphate pathway because i want to show you how the glycolysis pathway and how the pentose phosphate pathway are so intertwined and interconnected so now look this is an important step I am going to make this step blue this step right here is extremely important ok so in this step here I'm going to take glucose 6-phosphate and I'm going to convert into a really really funky name I hate that they call it this but it is how it is called 6 phospho glue cano lactone now that's a mouthful right but again what is this molecule here called it's called 6 phosphoglucomutase explosive 8 to 6 law smug look on a lactone i'm going to reduce the glucose 6-phosphate so in order for me to reduce him what kind of molecule what i need in order for this - i'm sorry actually i'm not reducing glucose 6-phosphate i'm oxidizing glucose 6-phosphate so i need a special molecule a special molecule in this step is going to be in a d p+ i'm going to take this nadp+ across this step nobody's going to do he's going to pick up some hydride ions you guys remember hydrides hydrides are just basically me saying I have a hydrogen with a proton in two electrons right with an overall kind of a negative charge there that's a hydride that's what a hydride is it's a proton with two electrons he's going to pick up some hydrides from the glucose 6-phosphate and get converted into six boss mangu con el acto now in order for that to happen if you guys remember anytime you see nad or NADPH always remember that there is a dehydrogenase enzyme there so this enzyme here is going to be extremely important he is called glucose 6-phosphate dehydrogenase so again this enzyme is called glucose 6-phosphate dehydrogenase extremely important enzyme because this is going to be one of the enzymes that determines whether this glucose 6-phosphate goes into six wassail connell act on and we'll talk about that when we discuss regulation now the six Philosopher's bukhan a lactone can then go into another step look what's going to happen here I'm going to take the six phospho glue on a lactone and I'm going to convert it into another molecule but specifically all I'm going to really do in this step is I'm just going to add some water so I'm going to add some water in this step and I might get out of proton as a result but either way I'm just adding some water into the step it's not really that important of a step but I just want to mention it and again this is actually going to be called six this one's a little easier phospho gluconate so what happens is I take six possible kind of lactones add a little bit of water into the step and get six phospho gluconate now six possible gluconate whenever i form in i'm going to go into this really really important step here in just a second now if you want to know this enzyme you can it's called lactamase so it's called lacto NACE don't get that confused with lactate that's an enzyme that actually converts you know lactose into glucose and galactose but now what I'm going to do is I'm going to take this lacked any things I'm going to convert six loss konna lactone into six Vaslav gluconate now I'm going to go on to another important step in this next step let's actually do the step in pink this is another important step here I am going to generate another set of NADPH is here so I'm going to take another nadp+ and convert it into in a DPH now to clarify something glucose 6-phosphate is six carbons let's put that right up here above it six carbons this is a six carbon molecule six phosphate wakana lactone is a six carbon molecule six phosphate bukhan a lactone is a six carbon molecule this next molecule that we're going to talk about is called when six blocks will look on a lactone is acted on by nadp+ to nadph I'm going to form a molecule called ribulose 5-phosphate now when i form ribulose 5-phosphate this is important and the reason why this one is important is because he's going to get ready to turn into another molecule that we use for a lot of different processes like synthesizing nucleotides synthesizing DNA synthesizing RNA synthesizing nad S&F a DS and coenzyme a we'll talk about that will list it but this carbon rib ulos five phosphate is a five carbon molecule so what does that mean if I went from a six carbon molecule to a five carbon molecule that means I lost a carbon in the form of co2 so there was some type of decarboxylation reaction decarboxylation you know decarboxylation is just basically when you're removing a carbon in the form of co2 just like carboxylation would be ab adding in a carbon in the form of co2 or sometimes even bicarbonate okay now we got this ribulose 5-phosphate there's two fates of this ribulose 5-phosphate Oh what is the enzyme that catalyzes this step this step right here is catalyzed by six phospho gluconate d hydrogenase now this enzyme isn't as important as glucose 6-phosphate dehydrogenase this enzyme is important nonetheless but it is not as important are not as significant as compared to glucose 6-phosphate dehydrogenase a condition that we'll talk about with respect to the school assists glucose 6-phosphate dehydrogenase if he's deficient it can lead to a certain type of hemolytic anemia with Heinz body formation all right this rib ulos 5 phosphate what can happen with this rib Bulow's 5 phosphate I can take this rib ulos 5 phosphate and I'm going to have two fates for it one fate is going to be for the formation of two different models but it depends upon the enzyme now Ribble owes 5 phosphate if it's acted on by a special enzyme and this enzyme is an isomerase enzyme so let's say there's an isomerase you know all isomerases are doing is they're just shuffling different carbons around so for example I can shift rib ulos to another molecule and this new molecule that I'm going to form is called ribose 5-phosphate ok so now I'm going to have my ribose 5-phosphate and then I'm going to have my rib ulos 5 phosphate all I'm doing is I'm switching around different types of atoms for example this rib ulos 5 phosphate can actually be converted into another molecule now this molecule is called ribose 5-phosphate now the only difference between ribose 5-phosphate and rib ulos 5 phosphate is all I'm doing is I'm switching you know rib ulos 5 phosphate is in the ketone form you know ketone is basically you have a carbon here let's say I have a carbon here and it's got a double bond oxygen in between two carbons this is a ketone so this has a ketone form whereas ribose is a aldehyde so you know aldehydes they're specifically having a carbon double bonded to an oxygen with another carbon and then on the other part they have a hydrogen all I'm doing is I'm utilizing this enzyme which is called my summaries to switch the ketone to an Al dive that's all that's happening so nothing crazy I'm just shifting around a little bit with these oxygens right just shifting around a little bit so I'm sure I'm shifting a ketone into an aldehyde now this other one is extremely interesting we'll talk about this more in organic chemistry but this enzyme is called a epi Maurice so it's called this for example this is ribulose 5-phosphate isomerase this is ribose 5-phosphate epi Maurice but specifically on the third carbon so it's actually occurring on the third carbon now I'm going to I'm going to really really dumb this down because we're going to talk about it but what we're going to make now is as a result of taking this epimer a sends on and converting rib ulos by phosphate I'm going to convert this into xylose 5 phosphate now what is the difference between rib ulos 5 phosphate I'm sorry between ribose 5-phosphate in the xylose 5 phosphate really because when I'm taking this guy and converting it into ribose 5-phosphate I'm just having an isomerization reaction when I'm taking Regulus 5 phosphate and converting into xylose 5 phosphate I'm utilizing this at the Meurice enzyme now epimers are basically what's called diastereomers like I said we'll talk about this more in organic but this is called a dye a stereo mer what it means is that they different in chirality in one carbon so for example let's say for example on the third carbon so let's say that on the third carbon the fourth carbon and the fifth carbon of this molecule versus the third carbon fourth carbon and fifth carbon of this molecule let's say that the RHIB ulos 5 phosphate was our meaning that it rotates to the right I'm sorry clockwise this one rotates counterclockwise and let's say that this one rotates counterclockwise if they were complete what's called enantiomers the stereo centers would invert and they would turn into ass ar-are but the difference is is that these are not enantiomers they're diastereomers so they different only one stereocenter so for example instead of them being let's say there are SS this would be our are the only stereocenter that they're now differing in with respect to each other is now going to be this third carbon they're going to have the same point there but they're going to now have these carbons being the inverted form okay so they're diastereomers they're not completely enantiomers their differing in one stereocenter okay anyway that's enough for the organic part of it now what I'm going to do is I'm going to take these two molecules and I'm going to fuse them together that's what I'm gonna do here I'm going to take the xylose 5 phosphate and I'm going to take the ribose 5-phosphate I'm going to fuse these two together when I do that I'm going to have a special enzyme working on these two guys this enzyme we're going to call a trans catalase enzyme so this is going to be called a trans key de lys enzyme you're not special about trans Quiles enzymes they have thiamine pyrophosphate as a component of the munis I mean pyrophosphate is a lot of the vitamins it's very very important vitamin right so thiamine vitamin b1 it's very very important in this step because it's going to act as a coenzyme thiamine pyrophosphate what's happening is trans Quiles is going to transfer a to carbon so it's transferring two carbons I know it might seem funky the way I remember it but it helps me I like to think that a ketone is in between two carbons so it helps me is just simply being able to remember that this guy's transferring two carbons so he's going to transfer two carbons so what happens is I'm going to transfer this ribose 5-phosphate I'd say take two carbons from him and I transferred onto the xylose 5 phosphate so I'm going to lose two carbons for him so he's going to go from again this is 5 carbons this is 5 carbons here nothing changed all I did was I had a summarization an epimer ization this 5 carbon and this 5 carbon I'm going to transfer two onto him and he's going to gain 2 that means he'll turn into a 3 carbon fragment that three carbon fragment is called glyceraldehyde I'm going to put glyceraldehyde 3-phosphate we're just going to abbreviate it here so again this is called glyceraldehyde 3-phosphate that's one product of this reaction so one product is going to be glyceraldehyde 3-phosphate now this one gains the two carbons so he transfers two carbons on to the xylose by phosphate and the xylose 5 phosphate gets converted into what's called said yellow pepto's 7 phosphate oh sweet goodness okay so scheduled ohef toast 7 phosphate is now formed and it's easy to think you know because it's by coincidence that the number that the the phosphates on tells you how many carbons there is so for example ribose 5-phosphate it just so happens to be 5 carbons xylose 5 phosphate just so happens to be 5 carbons glyceraldehyde 3-phosphate just so happens to be 3 carbons said you low kept Oh 7 phosphate just so happens to be 7 carbons but we know that because this was 5 this was 5 and all I did was I transferred two carbons from him to him okay now what can happen is this glyceraldehyde 3-phosphate has two destinations one is you guys have probably recognized that these are the two same molecules so what can happen with this goes throughout i3 phosphate depending upon the body's demands which we'll talk about he could technically get fed into the glycolytic pathway let's show that here so technically this guy could get converted right here you could actually be fed into glycolysis if we need to okay or he could be involved in gluconeogenesis it just depends upon the body's demands which we'll talk about because Google Nia Genesis we can make glucose glycolysis we'll go and make ATP okay but let's say that we don't need that we need to do something else let's say we need to make we need to do another process so now what I'm gonna take this glyceride i3 phosphate I'm going to combine it with the schedule o happed o 7 phosphate so now I'm going to fuse these two guys together so now this guy here and this guy here are going to react okay what happens here there's another enzyme let's do this one in a different color let's do this one in black this is going to be called a trans aldolase and this one is going to be transferring three carbons so again I just like to remember ketone it's in between two carbons so transfers to carbon fragment as default trans aldolase transfers three carbons okay so what is he going to do well he only has three carbons so he can't lose them this guy has seven he can definitely donate so what he's going to do is he's going to take three carbons from this guy and transform onto glyceraldehyde 3-phosphate so then what happens to the glycerol 3-phosphate when he gains three carbons when he gains three carbons he turns into another familiar molecule that I know you guys have heard of called fructose 6-phosphate where have we seen fructose 6-phosphate before I know I've seen it in glycolysis so where can this go then it can get fed up into fructose 6-phosphate so we'll just show like this for right now if you get fed into the glycolytic pathway but depending upon the body's needs it might go somewhere else but when the said you low hepta 7 phosphate when there's the three carbons transfer from him he loses three carbons so what happened to him then he loses three carbons and turns into a four carbon molecule that four carbon molecule is called a RIF throws for slaw sweet okay now you guys can imagine fructose 6-phosphate just by coincidence they're the faucets on the sixth carbon how many carbons will he have then he will have six carbons and again this is just by you know coincidence at all this is happening but it's nice erythro four phosphate you can imagine that it would have four carbons okay now you think we're done below or not okay we got one more thing that can happen this erythro spore phosphate I can do something else with it I can react it with another molecule that we might have just hanging around there there's another molecule hanging around and this one is called okay let's say you remember that rib ulos 5 phosphate a tribulus 5 phosphate let's a have another rib ulis 5 phosphate over here and that rib ulos 5 phosphate I have it acted on by a epimers enzyme if it's acted on by an epi maurice enzyme what does it get converted into you guys know that it gets converted into specifically xylose 5 phosphate okay well now what the body is going to do is it's going to take the silos 5 phosphate and it's going to react it with this a rigorous 4 phosphate now if these two react the silos 5 phosphate and the erythritol phosphate are going to be acted on by another enzyme that enzyme is called a trans kita less enzyme so I'm going to have another enzyme which is called a trans keto lace enzyme and again it has thiamine pyrophosphate as of coenzyme a and again it's transferring how many carbons is transferring two carbons so it's a two carbon transferring and done it's going to transfer two carbons from the xylose 5 phosphate onto the array throws four phosphate now if he's transferring two carbons then this 5 carbon will lose two carbons and turn into a 3 carbon molecule this three carbon molecules called glyceraldehyde 3-phosphate not so bad and we already know where he can go we'll just draw a red line for right now showing it feeding over here into glycolysis but the two carbons that are transferred from this 5 carbon molecule are put onto this four carbon molecule and it leads to the formation of ruk tous 6-phosphate and now we synthesize this fructose 6-phosphate and you guys already know where can this fructose 6-phosphate go you can also be fed into glycolysis ok this step here 1 2 3 and 4 these 4 steps here aren't involved in a specific part of the pentose phosphate either because it's actually divided into two parts what are the two parts here one is actually called the oxidative phase that's the four step one okay this is the four stepper the four step one that we went over and what is that including again it includes glucose 6-phosphate going to glucose 6-phosphate dehydrogenase I'm sorry glucose 6-phosphate being acted on by glucose-6-phosphate dehydrogenase to make six loss will be kind of lactone six loss work on a lactone being acted on by lactamase to make six phosphate gluconate six loss to a gluconate act being acted on by six phosphoglucomutase which is also going to convert anybody positive to NADPH and generating a co2 to make rib ulos five phosphate and then the conversion of Rebel Alliance phosphate into ribose 5-phosphate and xylose five phosphate that is the oxidative phase the main purpose of the oxidative phase is two things one thing is to make in ad pH and the other thing is to make ribose 5-phosphate that is the purpose of the oxidative phase it's to make a lot of NADPH and to make a lot of ribose 5-phosphate now we'll talk about why that's important just a second but what's the other phase the other phase is actually called the non oxidative phase and I like to think about this one is just that carbon shuffling reacts carbon shuffling reactions in other words you see all these steps here afterwards after the fourth step so in other words this step here we can take me to the fifth step the sixth step the seventh step all those all these carbons shuffling where I'm going from ribose 5-phosphate in xylose five phosphate into glyceride three phosphate and said Oh hebdo seven phosphate these two reacting and forming fructose 6-phosphate and rigorous four phosphate this guy reacting with the xylose 5 phosphate to me it goes right on through phosphate and fructose 6-phosphate those are my carbon shuffling reactions and what these are good for is that I didn't really show it here but look at this you see this step here me going from ribose 5-phosphate to glycerol 3-phosphate this is reversible this going from here reversible reversible reversible and this is also reversible and reversible what did that mean that means I can take things from glycolysis like what like the glyceraldehyde 3-phosphate and help to make ribose 5-phosphate so I can actually take glitterati 3 phosphate fructose 6-phosphate and do what react these two together to get erythritol phosphate and xylose 5 phosphate which can actually be converted into ribose 5-phosphate or eventually right then what happens then I can take that a red rose for philosophy active reactor with another glycolytic intermediate and make glyceride i 3 phosphate and schedul hebdo's if these two react I can get ribose 5-phosphate and xylose by philosophy so from the non oxidative pathway what can I do I can make ribose I'm going to put our 5p on just do it ribose 5-phosphate without making NADPH and this can come from glycolytic intermediates so the whole significance of this pentose phosphate pathway is that I have two phases the oxidative phase which is generating a lot of NADPH is and a lot of ribose 5-phosphate and the non oxidative phase which is all those carbons shuffling reactions which the whole purpose is is I can make ribose 5-phosphate without making NADPH oh and I can use glycolytic intermediates or I can take ribose 5-phosphate and make de like olynyk intermediates so in the reverse concept I could take ribose 5-phosphate and put r5 P and convert that into glyco lytic intermediates so that is pretty cool okay so now that we understand this process here let me just mention here what is the significance of NADPH what is the significance of ribose 5-phosphate and then we're going to stop this video and do another video on the regulation okay let's take here and say NADPH I already told you guys that NADPH is very very good at being a good reducing agent he has reducing power they call it right so he's a good reducing agent he has a reducing power for what type of reactions for any type of biosynthetic reaction what do I mean well if you guys have watched a lot of these metabolism videos you know that he's good for fatty acid synthesis we need him in a lot of those fatty acid synthesis steps specifically the reduction steps if you guys watch the cholesterol metabolism video he's also important in cholesterol metabolism for being able to convert the hmg-coa and to the mevalonic and he's also good for other different types of processes like one of them is specifically called nucleotide we actually needed for the nucleotide metabolism so synthesis of nucleotides and we didn't talk about it too much but it's also needed for neurotransmitter synthesis a lot of different things that this sucker can be used for so and we'll talk about a lot of these things like the nucleotide synthesis and the neurotransmitter synthesis and individual systems and videos but just realize that this guy has a lot of significant things that he's involved in he's insignificant for making fatty acids cholesterol and nucleotides and neurotransmitters what about ribose 5-phosphate ribose 5-phosphate is equally as important and you'll see I should actually put one more thing here if I can squeeze it in there I'm actually just erase this I'm really really important thing that I did not mention it's also good for free radical reactions and we'll discuss that in the next video really really important for free radical reactions it's acting as what's called an anti oxidants basically and you'll see exactly how it's helping it's not technically an antioxidant but it's helping antioxidant enzymes okay and the last one we said was ribose 5-phosphate now ribose 5-phosphate is important because he is involved in making a lot of different nucleotides like what you know he's important for making you know nucleotides and specifically for nucleic acids because you know nucleotides are the basic building blocks for the nucleic acids like what like DNA RNA Oh it's also good for making ATP we actually use it as a building block for ATP we use it for those electron shuttles within the Krebs cycle you guys have heard of them NAD+ and FA d he's good for making these and he's also good for making coenzyme a so he is very important in the synthesis of a lot of these different I'm gonna put here synthesis and then same thing so ATP synthesis nad be pot NAD+ synthesis FA D synthesis coenzyme a synthesis so he is very very important so you can imagine why these things are so significant any type of alteration within these could lead to disastrous effects specifically one that we'll talk about with respect to the free radical reactions is if there's a deficiency in a specific enzyme that generates these they can develop what's called a hemolytic anemia with Heinz bodies so put Heinz bodies for now okay we'll talk about that in the next video okay so now we understand the the way that this pathway is occurring that the two phases oxidative phase which real quickly glucose 6-phosphate to vi also kakano lactone 6la silicon will act on this fausto gluconate six fossil beginning to ribulose 5-phosphate and just the isomerization or epimer ization to ribose 5-phosphate and xylose five phosphate these are the oxidative phases okay but the non oxidative phases all these carbons shuffling reactions so when I take ribose 5-phosphate and xylose react in with the trans catalase react let's Rabbi 3 phosphate schedule a hug kiss with a trans outer lace and then reacting xylose 5 phosphate with a red rose 4 phosphate with the trans Quiles and making different glycolytic intermediates this is important for making ribose 5-phosphate without needing to make NADPH or as well as taking ribose 5-phosphate and making specific glycolytic intermediates which also can be used in gluconeogenesis and we'll talk about that in the next video alright guys I hope all this made sense I hope you guys did enjoy it if you did hit the like button subscribe please and please comment down in the comment section we look forward to hearing from you guys all right in the next video we'll go on to this in a little bit more detail all right engine arts until next time

Channel: Ninja Nerd

Views: 464,323

Keywords: pentose phosphate pathway, metabolism

Id: eXXpUxg9vn4

Length: 34min 16sec (2056 seconds)

Published: Tue Jun 13 2017