March 24, 2023

Hello friends welcome to creative medicine in this lecture we will learn about hello friends let us now learn some important points about the enzyme inhibition in the enzyme inhibition we have competitive enzyme inhibition non-competitive enzyme inhibition suicidal inhibition and low steric inhibition and feedback inhibition so if you see first we have competitive

Enzyme inhibition okay so in the competitive enzyme inhibition if you see this enzyme is analogous to the substrate okay now this is the substrate okay now this enzyme is almost analogous to substrate that means it will welcome and bind to the substrate like this so this enzyme by binding to the substrate like this this will inhibit the enzyme uh sorry this will

Inhibit the uh substrate to yeah normally normally sorry this enzyme will this this is the substrate this is the enzyme and this will result in formation of products okay now what we do is this is the substrate okay and we also have this enzyme and now along with this is substrate and enzyme i will give one more molecule which is an inhibitor so here i am giving

This inhibitor this inhibitor almost looks like substrate it is analogous to the substrate now there are many enzymes there will be one enzyme molecule similarly there won’t be one substrate molecule there will be many substrate molecules many enzyme molecules and many inhibitors so now normally these two inhibitors will bind to these two substrates okay that occurs

Normally but now because i have given the inhibitor now this enzyme will bind to this substrate this enzyme will bind to this inhibitor so as a result this substrate is left so the reaction has been inhibited right so whenever you give an inhibitor now this inhibitor is almost structural analog of substrate and as a result it is inhibiting the now substrate a enzyme

Complex and thus inhibiting the product formation okay so this is called as competitive inhibition that means this inhibitor is competing with the substrate for this site on the enzyme and has a result inhibiting the product formation okay this type of reaction which you see is called as competitive inhibition what is important here is the enzymes that the examples

This is the drug and this is the enzyme inhibitor if you see the statins will inhibit the enzyme hmg coa reductase dicameral will inhibit the enzyme vitamin k epoxide foreign will inhibit the enzymes acetylcholine esterase then if these are the uh one type and we also have some more like oxymade which is a competitive inhibitor these are just inhibitors not

Drugs okay this oxymade is a competitive inhibitor which inhibits lactate dehydrogenase it looks almost analogous to the substrate lactate then we have trans akonitase this transactions will inhibit a corny taste and this transform it is is almost analogous to the substrate then we have the enzyme melonate this melonate will inhibit succinate dehydrogenase and

This melonate will be is in structural analog with succinate when the enzyme then the inhibitor the comparative enzyme inhibitor hmg will inhibit hmg coa reductase and this hmg is analogous to hng coa right so these are the examples of competitive inhibition okay next one more important thing is the graph to explain you the graph itself so yeah the graph is if

You see this is the baby max and this is the substrate concentrations sorry velocity and this is the substrate concentration so if you see this enzyme okay the if you use only substrate there is increase in the reaction when you use enzyme and whence or once all the sides have been filled then the reaction will become stabilized first the velocity of reaction will

Increase and after complete saturation the velocity of reaction becomes same even with the increase in the substrate concentration now the velocity of reaction becomes constant even when you increase the substrate concentration now if you use this is only subscript now you are using substrate plus inhibitor now because of the inhibitor the rate of the reaction will

Definitely decrease it won’t be similar to the previous one so there is decreased and has you increase the substrate now when the concentration of the substrate is increases and when the concentration of substrate is more than the inhibitor for example see there are only these two in three substrates and there is only one inhibitor okay and there are two inhibitors

Think that there are two inhibitors there are three substrates and there is this is the enzyme okay there is increased chances of i mean almost the this substrate this inhibitor this substrate might bind okay and again take a second situation where i have increased the substrates now to such an extent that the inhibitors will almost be negligible that means there

Is increased chances of these substrates to get by rather than inhibitors so if you see the probability of binding substrates here it will be around 2 3 4 5 6 7 7 out of 9 whereas the probability of inhibitor to bind to this enzyme will be around 2 out of nine so obviously this will be increased so slowly when you completely increase the substrate concentration

Then obviously a point will reach where no inhibitor will be binding to the enzyme so this is when the v max is reached so this is how you see the graph first substrate and inhibitor okay so this is about the quantitative inhibition then after the competitive inhibition we have second type of inhibition which is called as non-competitive inhibition so in this

Non-competitive inhibition if this is the enzyme okay now the substrate will bind to this site okay and it will result in formation of product very good now i have given an inhibitor now the inhibitor will come and bind to the other side okay now this inhibitor will come and bind to this side once the inhibitor binds to the enzyme to the other side now what this

Inhibitor does is this inhibitor will bring about conformational change in the enzyme in such a way that now the substrate cannot bind to this enzyme because the substrate is looking like this like now there is no you know site where uh this like this site because of this conformational change so obviously this is inhibiting the and then completely right so if

We draw a graph here the similar graph okay i will first draw the normal graph this is the normal graph where the rate of reaction increases and after a certain extent the rate of reaction becomes constant even on increasing the substrate concentration this is velocity now now we are giving this inhibitor this inhibitor is has inhibited the uh substrate enzyme

Complex by bringing about conformational change of enzymes so as a result now the the velocity of reaction will decrease okay it will decrease and obviously it won’t reach the maximum velocity because this conformational change of the enzyme will not is not reversible and has a result there is no chance that this substrate will again bind to this enzyme right and

This enzyme is uh not useful right so the this the v max is less so if you see in the non competitive inhibition v max decreases and what about the cave k n will be constant so here v max decreases but k m is constant in non-competitive inhibition whereas if you see in the competitive inhibition if you see this v max is constant whereas k m decreased right this is

The k this is the game so it is decreased so this is about the competitive inhibition and here you can see in non-competitive inhibition maximum velocity is increased but km is constant right now right there is one more important thing examples we should see so if you see the examples most of the poisonous agents are non-competitive inhibitors like cyanide will

Inhibit um salto chrome c oxidase non-competitively the enzyme iodo acetate will inhibit the sorry the compound hydro acetate will inhibit the enzyme glycerol dehyde 3 phosphate non-competitively the enzyme fluoride will inhibit enolase non-competitively the compound disulfiram will inhibit aldehyde dehydrogenase non-competitively british anti-levicite tile or

Diamond capital these will inhibit the sh group of enzymes non-competitively as the night will inhibit alpha keto gluta red dehydrogenase non-competitively the enzyme fluoroacetate will inhibit uh akonitis whereas dye iso profile floral phosphate will inhibit serine proteases so these are the different compounds which inhibit the respective enzymes so this is

About the non-competitive inhibition then after non-competitive inhibition we have third type of enzyme inhibition which is called as societal inhibition okay in this suicidal inhibition here there is inhibition inhibitors will bind to the enzyme and this inhibitor is so potent that it will form irreversible it will become irreversibly it binds to the enzyme okay

That is about suicidal inhibition and this inhibitor will also die resulting in depth of the enzyme also so the examples of suicidal inhibition are we have allopurinol is a suicidal inhibition will inhibit the xanthane oxidase so if you see i love urinal also combines with the xanthine oxidase and it forms a log xanthin this aloe xanthin will again inhibit the

Xanthine oxidase more than the normal so in this inhibitor combines with the enzyme to form inhibitor enzyme complex which is more and more inhibits the enzyme okay so this is called a suicidal inhibition so here alope is not normally inhibits the xanthine oxidase but allopurinol combines with the xanthine oxidase to form aloxanthin now it is unload something

Even more inhibits the xanthine oxidase so if you see one more enzyme one more example we have trypanosomiasis this trypanosomiasis for this there is an enzyme called there is a compound called as difloromethyl or methane is formed this dichloromethyl or anything will inhibit ornithin d carboxylase whereas aspirin will also acetylize the cyclo oxygenase active

Site and thus inhibits prostaglandin synthesis so this is about the suicidal inhibition then after suicidal inhibition we have something called has feedback inhibition so if you see in feedback inhibition in this if you see there is an enzyme okay which will combine with the substrates to form the product now this product will inhibit the enzyme activity this is

Called has feedback inhibition for example uh with the help of urine synthesis amp is formed this amp is the end product of purine synthesis now this amp will inhibit the first step of purine synthesis so this is about the feedback inhibition so these are the different ways of inhibition of the enzyme thank you guys for watching my lecture thank you thank you and thank you for watching

Transcribed from video
9 4 enzyme inhibition mp4 By Creative Medicine