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Hello everyone,
Spare me the rants – I have read the other threads, but I still don't quite get it conceptually.
As far as I know, Km is used as a means of describing the affinity for the substrate. It's value is at 1/2Vmax. Now if you increase the concentration of enzyme in your solution, it makes sense that your overal rate will increase (double the number of workers the job will get done faster). If Vmax increases as a result of increasing the concentration of enzyme, then won't 1/2Vmax be higher? Therefore, wouldn't the value of Km also increase?
Since this is not the case, I want to come up with an analogy that I hope someone can confirm is correct. It is to my understanding that we assume that the concentration of enzyme within our solution does not change and that the only thing that does change is the concentration of substrate. We know that if we have a set amount of enzyme in our solution, then the more substrate we add, the faster we will produce our product. That is, however, until we saturate the solution with our substrate. As a result, our rate of reaction can no longer increase because we don't have enough enzyme to accommodate oversupply of substrate – our rate evens out.
Now lets say hypothetically we do increase our concentration of enzyme in our solution. It then makes sense that our maximum velocity would increase because we have a larger supply of enzymes which can accommodate the large supply of substrate. With that being said, 1/2Vmax would also increase. So it makes sense that if 1/2Vmax is equal to Km, then Km should also increase. However, this is not the case and its because Km is entirely based on the affinity for the substrate at 1/2Vmax. Regardless of whether we add more enzyme or more substrate, the Km will always be the same because at 1/2Vmax, half of the enzymes are working while the other half are not. So even if we increased the amount of enzyme to accommodate the large supply of substrate, our Vmax would increase and so would our 1/2Vmax, but the ratio of enzymes working to those not working would be the same. For example, lets say I originally have 10 enzymes where 5 enzymes are working and another 5 enzymes not working at 1/2Vmax. Now lets also say that I add more enzyme and Vmax increases and therefore 1/2Vmax also increase. Now that I have done this, lets say I have 20 enzymes in total, where 10 of them are working and another 10 are not working. The ratio, regardless of whether we increase the amount of enzyme or not, is still the same.
Is what I just wrote correct?
Also can someone explain to me why binding affinity is inversely proportional to Km?
Spare me the rants – I have read the other threads, but I still don't quite get it conceptually.
As far as I know, Km is used as a means of describing the affinity for the substrate. It's value is at 1/2Vmax. Now if you increase the concentration of enzyme in your solution, it makes sense that your overal rate will increase (double the number of workers the job will get done faster). If Vmax increases as a result of increasing the concentration of enzyme, then won't 1/2Vmax be higher? Therefore, wouldn't the value of Km also increase?
Since this is not the case, I want to come up with an analogy that I hope someone can confirm is correct. It is to my understanding that we assume that the concentration of enzyme within our solution does not change and that the only thing that does change is the concentration of substrate. We know that if we have a set amount of enzyme in our solution, then the more substrate we add, the faster we will produce our product. That is, however, until we saturate the solution with our substrate. As a result, our rate of reaction can no longer increase because we don't have enough enzyme to accommodate oversupply of substrate – our rate evens out.
Now lets say hypothetically we do increase our concentration of enzyme in our solution. It then makes sense that our maximum velocity would increase because we have a larger supply of enzymes which can accommodate the large supply of substrate. With that being said, 1/2Vmax would also increase. So it makes sense that if 1/2Vmax is equal to Km, then Km should also increase. However, this is not the case and its because Km is entirely based on the affinity for the substrate at 1/2Vmax. Regardless of whether we add more enzyme or more substrate, the Km will always be the same because at 1/2Vmax, half of the enzymes are working while the other half are not. So even if we increased the amount of enzyme to accommodate the large supply of substrate, our Vmax would increase and so would our 1/2Vmax, but the ratio of enzymes working to those not working would be the same. For example, lets say I originally have 10 enzymes where 5 enzymes are working and another 5 enzymes not working at 1/2Vmax. Now lets also say that I add more enzyme and Vmax increases and therefore 1/2Vmax also increase. Now that I have done this, lets say I have 20 enzymes in total, where 10 of them are working and another 10 are not working. The ratio, regardless of whether we increase the amount of enzyme or not, is still the same.
Is what I just wrote correct?
Also can someone explain to me why binding affinity is inversely proportional to Km?