21

Chemistry / What is the relationship between enzyme activity and substrate concentration?

« on: 24/01/2021 12:26:53 »

Hello

If an enzyme converts 1umol of substrate per minute when the substrate concentration is 1mM, what will be the conversion rate when the concentration is 0.1mM?

Is there a quick calculator for that?

Thanks

22

Physics, Astronomy & Cosmology / How do indoors diesel heaters handle exhaust gases?

« on: 23/01/2021 12:37:26 »

Hello

How do indoors diesel heaters handle exhaust gases?

I am puzzled.

Thanks!

23

Chemistry / Re: Can enzyme act as ligands?

« on: 21/01/2021 08:57:46 »

Re: Can enzyme act as ligands?
« Reply #3 on: 17/01/2021 10:02:14 »

Any input please?

24

Physics, Astronomy & Cosmology / How can I calculate the force needed to rotate an object?

« on: 18/01/2021 18:36:34 »

Hello

If an object is hanging, how can I calculate the force to just start rotating it with minimal velocity?

Assuming no friction or any other obstacle from where it hangs.

Thanks!

25

Technology / Re: What are the methods to reverse a rotation?

« on: 17/01/2021 17:28:19 »

I can't get my head around.

26

Technology / Re: What are the methods to reverse a rotation?

« on: 17/01/2021 14:06:27 »

Thanks but if you have a rotating shaft, can you put an addon on the shaft so that you get a reverse rotation?

Did you not like the answer?

gears, wheels, other simple machines for direct mechanical transfer.

Got it, thanks!

27

Technology / Re: What are the methods to reverse a rotation?

« on: 17/01/2021 11:16:21 »

Thanks but if you have a rotating shaft, can you put an addon on the shaft so that you get a reverse rotation?

28

Chemistry / Re: Can enzyme act as ligands?

« on: 17/01/2021 10:02:14 »

yes

Thanks, any example/reference please that says that?

29

Technology / What are the methods to reverse a rotation?

« on: 13/01/2021 19:41:31 »

Hello

if something rotates clockwise, how can we use that rotational movement to make something else to rotate anticlockwise?

What are the available methods for this?

Thanks!

30

Chemistry / Can enzyme act as ligands?

« on: 11/01/2021 09:14:47 »

Hello

Can enzymes be used to bind specific molecules without converting them?

Thanks!

31

Physiology & Medicine / Is something injected in the subcutaneous tissue passing through the liver?

« on: 09/01/2021 14:58:46 »

Hello

If something is injected in the subcutaneous tissue, will this pass through liver?

As I imagine it, it will be injected into the interstitial fluid of the subcutaneous tissue. It will then flow into the lymph or vein blood and then into kidneys to be excreted.

Would it pass through the liver first and then the kidneys or the opposite?

Thanks!

32

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 05/01/2021 09:33:00 »

Is it better to use Mass spec?

Probably not in this case.

Do you have or can you get  gluconic acid?

I don't think so. I think I will need to invest in the special gluconate columns, I suppose, thanks!

33

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 04/01/2021 17:45:35 »

Are you using a mass spec detector?

Nope, a Refractive Index detector is used.
Is it better to use Mass spec? I will have to ask a lab to do it.

34

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 03/01/2021 20:40:55 »

Well... how do you measure ("see") your glucose on the hplc? If you're using a mass spec detector, please stop injecting phosphate buffer into it.

I was told that phosphate buffer does not interfere with HPLC/RID glucose detection.

35

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 02/01/2021 16:57:08 »

The first thing I would do would be google it and see if someone has done it before.
Something like this
https://www.shodexhplc.com/applications/lc-ms-analysis-of-glucose-and-gluconic-acid-vg-50-2d/

The other thing I would do would get a sample of the gluconic acid.
That way I could measure it as well as measuring glucose.
If, for example, 1% of your glucose is oxidised, it will be difficult to measure the change in concentration- especially as there will be some evaporation  when the material is exposed to the air.
But if 1% of the glucose if converted to the acid, you will see the acid easily.

How exactly, will I 'see' (I assume measure) the acid? Don't forget the solution already has strong buffer salts, e.g. sodium phosphate.

36

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 02/01/2021 12:42:53 »

I have not been able to find online whether HPLC can distinguish between glucose and gluconate.

Well, it would if I was doing it but it seems that you don't know how, because, if you did, you would have checked that first.

How would you do it? Do you use special columns or methods?

37

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 01/01/2021 15:20:41 »

no glucose reacted

How do you know?

But, the most likely answer is that diffusion from the air into your reaction vessel was too slow.
Did you put the solution in a shallow flat tray, a beaker or a conical flask?

I measured glucose with HPLC. Could it be a possibility that glucose and gluconate where measured together? I have not been able to find online whether HPLC can distinguish between glucose and gluconate.

The reaction took place in a square beaker and the solution had a square shape.

38

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 01/01/2021 09:56:18 »

Obviously, with no stirring, the reaction is going to be much slower further from the surface.
So the "rate of reaction" isn't going to be well defined, is it?

What are you actually trying to find out?

I put glucose oxidase in an unstirred glucose solution under ambient conditions and no glucose reacted. I want to know if oxygen is responsible for that.

39

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 31/12/2020 18:29:12 »

The question is, will oxygen diffuse from air into the water

Obviously, yes

Life is one of those "reactions" that occurs in water.

A lot of "life" involves the enzymatic oxidation of glucose.
But you didn't want that answer either.

I obviously know that but I am not sure if it is representative of regular lab conditions, i.e. considerable glucose concentration and considerable enzyme concentration. Also, oxygen is heavily facilitated and transported and stored in cells so I do not think that a living organism oxidising glucose is representative of a 50mM glucose solution with 10,000 units of enzyme under ambient air and no stirring.

40

Physics, Astronomy & Cosmology / Re: How does oxygen limits water based reactions?

« on: 30/12/2020 11:43:16 »

My question has several assumptions which are easy to assume.

E.g. we have glucose oxidase in a still solution with glucose. Let's say we have 10,000 units and the concentration of glucose is 10mM. The question is, will oxygen diffuse from air into the water and react with the enzyme or this will not be enough and the enzyme will be restricted?

I am assuming room temperature, normal atmosphere, etc etc. I am not referring to extreme situations where we have 5kg of enzyme per litre or superheated water etc.

If the answer depends, I am asking what conditions would oxygen start limiting the reaction.

I do not understand what you find unanswerable in my question.

Of course, it will need to read 2 books to answer this but I don't want the answer to be two books, I want the conclusion from people who have relevant knowledge and experience or can provide estimates.