00:01
Is one of the few essential amino acids that cannot be synthesized by animals and then thus be provided in the diet.
00:08
Every year, tons of lysine are produced by microbial fermentation using the bee flavor.
00:13
The pathway of synthesis is shown on the board.
00:16
So you can see you start out with the substrate, aspartate, and then it goes through the enzyme aspartokinase.
00:23
Obviously, atp is being invested.
00:29
As a result, you produce the aspartopi.
00:34
Then aspartopi turns into the aspartate semi aldehyde.
00:40
Then it turns into diaminopimidylate.
00:44
And eventually, this turns into lysine.
00:48
So the product lysine will actually go back through this feedback inhibition and inhibit this enzyme, the aspartokinase.
00:57
So this basically is a negative feedback loop.
01:01
So this is explain why that using above pathway describe and explain why lysine production is low.
01:09
So this is because the product of the pathway lysine inhibit the enzyme aspartokinase.
01:43
So you can see that when the cell need lysine, obviously the lysine is missing in the cell.
01:54
Then aspartokinase is active to convert aspartate to aspartopi, then it put all the intermediate and eventually produce lysine.
02:05
When enough lysine is being produced, this act as a inhibitor, it will turn off this aspartokinase to prevent the excessive production of lysine.
02:58
So this is a mechanism to prevent the waste because you have enough lysine in the system.
03:05
Therefore, no more lysine is needed.
03:06
Itself serve as a switch to turn off the enzyme so that due to the accumulation of aspartate, no more aspartopi and other intermediate will be produced.
03:20
Therefore, the lysine will not be produced.
03:23
So this tells us how the lysine itself cause the production of lysine to be low.
03:31
This is because it has this feedback inhibition, which in directly turn off the enzyme to prevent the excessive production of lysine.
03:52
The second question says, suggest several possible methods that can be used to increase the production level of lysine and explain.
04:01
So one of the possible way is to make a genetic modified enzyme aspartokinase that resist the feedback inhibition.
04:48
So let's say this is the original enzyme.
04:52
It still have active site and then you have a allosteric site for lysine...