hey guys it's medicosa's perfect snail is where medicine makes perfect sense let's resume our biochemistry playlist in previous videos we talked about the properties of the enzyme the nomenclature or the classes of enzymes we talked about the mechanisms of enzyme activity we talked about the two theories number one the key and the lock Theory number two the induced fit Theory today we'll turn our attention to enzyme kinetics and those crazy graphs that everyone hates and we'll start with michaelis-mentin equation with that said now let's get started this is my biochemistry playlist please watch these videos in order most enzymes in your body are proteins enzymes are catalysts indeed they speed the rate of the reaction by lowering the activation energy however they do not change the equilibrium nor do they change the overall free energy the enzyme is like a shortcut it's a catalyst it increases the rate or the speed of the reaction for the purpose of your biochemistry exam the rate is the same as the speed is the same as velocity and we will symbolize this as V but hybrid causes speed and velocity are different I know in physics they are different but in Biochemistry no one cares because biochemists suck at physics here is the enzyme it lowered my activation energy but did not change the overall energy or the Delta G you still went from A to B A is the initial State B is the final State both of them could be called ground state but when you go uphill it's called the transition state enzymes are specific one enzyme for one reaction or one type of reactions enzymes do indeed love their substrate and this love relay relationship is known as Affinity so we can say that the enzyme urease has affinity for urea its substrate we talked about the six categories of enzymes before never ever forget that kinases add phosphate to the reaction therefore they are transferases they are transferring a phosphate conversely a phosphatase is an enzyme that breaks down plus takes away a phosphate from you by hydrolysis so it's a hydrolase this is the active site which is the front door but this is the back door or allosteric site who's gonna occupy the active site of the enzyme the answer is the substrate when the substrate binds the enzyme they make an enzyme substrate complex they literally hug each other and we discuss the two models for enzyme substrate interaction the old one is the key in a lock a truck in a dock a hand in a glove which is not very accurate the more accurate one is the induced fit model when they hug each other the substrate is gonna change the active side of the enzyme and the active site will change the substrate shape here is the Michaelis Mitten rubber oh my goodness I hit this shut up and calm your butt down it's easy some basic math when you have a relationship like this between a and b and you have a line going this way it's a direct relationship translation suppose that we started with this point let's call it one we go up here you will intersect with this point let's call it one however let's increase B for example all right if I increase B what do you think is going to happen to a well well let's intersect oh I see here the 2 is higher than one therefore as I increase B A increases two direct relationship conversely if you find the relationship between them and the line is going down words like this to the abyss it is inverse relationship let's play with this equation between A and B There is a direct relationship as long as C is constant next between a and C there is inverse relationship as long as B is constant how about the relationship between B and C direct relationship as long as a is constant can we do this with a plus sign in between yeah same thing between A and B inverse relationship as a goes up B goes down and vice versa provided that c is constant between a and C there is direct relationship between B and C there is direct relationship how do I remember all of this whenever you have two entities that are divisible by each other or subtractable from each other the relationship between them is direct conversely if they are multiplicable by each other or additive to each other it's an inverse relationship now let's look at this graph over coasters this is a line going to the sky not to the abyss no no no it's going to the sky therefore between the substrate concentration and the initial velocity of the reaction there is a direct relationship especially in the beginning because this first portion looks as if it's a straight line in real life you do not have just one substrate you have gesillions of these and it's not just one enzyme you have gesillions of these therefore we can argue that the more substrates we have the faster the reaction I.E direct relationship the greater the concentration of the substrate the faster the rate of the reaction direct relationship but hey Miracles is why didn't we keep going up up why did we Plateau why did we level off and flatten out like this great question because enzymes are proteins eventually they can get saturated do you remember my bio Energy Playlist remember when we talked about cell membrane transport we had passive transport no energy needed and we had active transport we needed energy do you recall the passive transport yeah we had simple diffusion we had osmosis just for water and we had facilitated diffusion what was the difference between simple and facilitated yeah miraculous it was true that both of them required no energy both of them happened along their electrochemical gradient however simple diffusion required no carrier protein however facilitated diffusion did require a protein carrier and this carrier protein will give you what specificity like the enzyme because enzymes are proteins just like a carrier a carrier is a protein an enzyme is a protein both of them will give you specificity what else competition what else saturation you level off this is why you hit your maximum V Max simple diffusion is a straight line going to the sky it never stops however facilitated diffusion because it's dependent on Carrier proteins that eventually will get saturated these carrier proteins will get sick and tired of being sick and tired and they will level off if you have watched my kidney physiology lectures at medicosisperfixnetis.com we talked about the proximal convoluted tubule look at this glucose is being transported and it needs a carrier known as sglt s for sodium GL for glucose t for transporter this transporter is a protein eventually if you have too much glucose you will saturate all of your Transporters because they are proteins they get sick and tired of being sick and tired and that's why the transport the reabsorption of glucose will go up until you saturate all of your proteins and then you level off and then you plateau and then you hit your V maximum what should I do next I cannot reabsorb glucose any longer you will start to lose this glucose in your urine oops so you cannot just expect to raise your serum glucose add infinitum and expect the kidney to reabsorb all of it it's not going to happen the kidney will try her best until the kidney saturates all of her sglt2 and then you will level off and the extra glucose will end up in the urine the legend has it that the ancient Egyptians were the first people to develop the pregnancy test the idea was very simple if you want to know if this lady is pregnant or not take a sample of her urine it's a physiological fact that during pregnancy the kidney will lower the a threshold for glucose I.E glucose will start to appear in the urine earlier than expected these sglt2 carriers will get saturated earlier than we expected so if the lady is pregnant there will be glucose in the urine we will add her urine to some plants could be wheat could be poorly if the barley grew it means there was sugar in the urine The Barley ate the sugar and The Barley grew but if the barley did not change it means there was no glucose in the urine and she's not pregnant it's all about the Vmax baby now back to Michaela's freaking Menton this is why you level off this is why you plateau because you saturated all of your enzymes which are proteins and this is called Vmax but let's go back to Step One between the substrate concentration and the initial velocity is a direct relationship here is another math fact if I say that a is directly proportional to B I can remove this proportional sign and put equal and multiply by constant so now this will become a equals constant multiplied by B can we do the same thing for Michael's mental sure since the velocity or the rate of the reaction is directly proportional to the substrate concentration I can remove this proportional sign and put equal constant multiplied by so it becomes V 0 or V naught which is the initial velocity equals constant times the saturation in the German language and I believe in Latin constant could be written with a K that's why we still have EKG or ECG it's the same concept encephalogram or encephalogram same origin K or C they are cousins so the constant is K why do you call it km why not f u because this is the constant of Michaela's freaking Menton oh they named it after them that's right the constant of Michaelis Mountain the Michaelis meant in constant multiplied by the substrate concentration still the relationship between the substrate concentration and the rate of the reaction is direct if the substrate concentration goes up their reaction rate goes up and vice versa Michaelis Minton started with this and then with experimentation and mathematical proof that took about 10 steps which is beyond the scope of this video they arrived at the michaelismentin equation which is this if you want me to make a separate video to describe the 10 steps of the mathematical proof I can do it but for now please memorize this michaelis-mentin equation this is the initial rate or initial velocity this is the maximum rate of the reaction substrate concentration Michael less mint and constant let me tell you the truth you will never reach the maximum in Practical terms theoretically yes you can hit it but practically speaking when we're talking about just biochemical enzymes you're not gonna help because you have gazillion enzymes in your body so instead of talking about Vmax which is a theoretical Point why don't we go back to Earth and talk about half of Vmax because we can actually reach this in the lab all right all right let me take half of Vmax which is this number times half now I'm here let's go hit the graph and then intersect with the x-axis what should I call this point this is the michaelisment and constant therefore instead of V I'll write half V Max because I'm getting practical now and this is the same as this by dividing each side by V Max we will get the V Max from here cancel it with this V Max then half equals substrate concentration over km plus substrate concentration do some scissors action one times km plus s equals 2 times s therefore K M plus s equals S Plus s which means km is almost the same as s that's exactly right if you do not believe me just look at the graph s is on the x-axis km is also on the x-axis or horizontal axis therefore km is the same as substrate concentration provided that we're talking about the velocity here that is half of V Max oh medical says this makes so much sense even if you slept throughout the lecture so far up to this point you can still answer every question correctly on your exam just listen to me carefully enzymes are catalysts I know that they boost the state of the reaction I know that the more enzymes you have the faster the reaction I.E the greater the V makes sense the greater the number the greater the V Max the lower the number of enzymes the lower the Vmax listen to me carefully enzymes are specific for the substrate they really love substrate urease enzyme will not work with any substrate except urea what do you call this love relationship Affinity we can assess Affinity by km however they are inverse related the higher the Affinity the lower the km the lower the Affinity the higher the km let's put all the equations here please pause and review and now let's look at the graph here's the control line okay if I draw graph a for you what do you think happened to V Max in order to understand what happens I'll take the same point from the x-axis and I will go up and then you hit B and you go to the y-axis and then you hit the control go to the y-axis and then you hit a and go to the y-axis which one has the greatest V Max a or b or the control of course a the therefore as you shift the curve upwards you're increasing the V Max conversely when you shift the graph downwards you are lowering the V Max let's play the same thing with the km let's do this now to understand what's happening to the km I'll take the same point on the y-axis and then you go here until you intersect with this x graph which is the dark green that's my X and then you go here here here here until you hit the control that's my control and then you go here here until you hit the Y and that's the Y which one has the highest km again km is seen on the x-axis of course y has the highest km and you remember that km is inverse related to Affinity which means that graph y has a higher Michaelis mint and constant but a lower Affinity conversely graph x has a lower km but a higher f Affinity put all of them in one slide if you shift that graph upwards you're increasing V Max which means what you're increasing the number of enzymes because they are directly related conversely shift the graph downwards you're lowering the V Max and you're decreasing the number of enzymes can you give me examples of Shifting the graph upwards yeah induction more gene expression make more enzymes DNA make more code for more how about upregulation oh more enzymes that's true more Vmax conversely examples of lowering the Vmax is repression of the genes that code for that enzyme down regulation of the enzyme or non-competitive inhibition which will be the topic of an upcoming video now let's turn our attention to shift to the left versus shift to the right when you shift to the left you're lowering km which means you're increasing Affinity hashtag activation potentiation or sensitization they love each other even more but when you shift to the right yes indeed km is rising however Affinity is dropping inactivation competitive inhibition D sensitization slap the equations on the slide and now you can kiss Michaelis Minton goodbye you can throw Michaelis and mentin in the Dustbin of History where they belong it's over baby this graph will help you answer every question correctly if you want to download these colorful notes they are available at medicosisperfect snails.com in the next video we'll talk about Lynn weaverberg plot where everything is reversed everything is upside down if you want to learn more about the sglt2 and the glute 2 receptors check out my renal physiology course at medicosisperfectness.com you can also download my general pharmacology course where we have more graphs my antibiotics course and my brand new surgery high heels course at medicosisperfectenetics.com for the limited time you can get a 40 discount towards any course by using promo code taxidrome at checkout I'll see you in the next video Until then please subscribe hit the bell and click on the join button you can support me here or here go to my website to download my courses be safe stay happy study hard this is medicosa's perfectionelis where medicine makes perfect sense