Best answer:

Answer by Delenovas C
may be you ‘ll get help in ChemIONS site

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Organic Chemistry: Introduction to the E2 mechanism. E2 stereochemistry – cis vs. trans, determined by antiperiplanar transition state. Protic vs aprotic solvents. SN2stereochemistry This is a recording of a tutoring session, published with permission of the student. These videos are offered on a “pay-what-you-like” basis. You can pay for the use of the videos on my website: www.freelance-teacher.com I offer tutoring via Skype. For more information, please visit my website to go. For the printable “handout” discussed in these videos, go to my website. For a playlist with all the videos in this series can be found here: www.youtube.com
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Question by : Can anyone help with biochemistry question on solvents and solutes?
30% saturated ammonium sulfate is added to a mixture of 2 proteins. A protein-precipitation, while the other remains in dissolved substance. Explain the molecular basis of this separation?

Best answer:

Answer by Jahansha
AMMONIUM SULPHATE PRECIPITATION
Ammonium sulphate precipitation is the most commonly used salt ppt because it is highly soluble in water, it stabilizes most proteins in solution (although it may denature some MAbs), and helps reduce the lipid content of the sample.

Ammonium sulphate ppt removes up to 50% of contaminating protein, and therefore reduces the load for subsequent chromatography. Most precipitated proteins retain their activity and native conformation, and can be redissolved easily. Ideal for crude and dilute samples.

At 0oC a saturated solution of ammonium sulfate is 3.9 M. This is called a 100% solution (because it is the maximum amount of ammonium sulfate you can have in a solution – not because it contains 100 g/100 ml). Generally some proteins will precipitate at 20%, others won’t precipitate until close to 80%, but most proteins will precipitate at 80% or less ammonium sulfate concentration. Sometimes solid ammonium sulfate is added, but generally there is less risk of denaturing the proteins and a clearer separation of precipitated proteins if a saturated solution of ammonium sulfate is added.

To make 100% saturated ammonium sulphate at 25oC:
To 1000 ml dH2O add 766.8 g of (NH4)2SO4. pH to 6.8-7.0 with 5 or 10 M NaOH.
So, there is 541.2 g of ammonium sulphate per 1 of saturated solution.

To precipitate 2.5 ml of a solution by making it to 80% with ammonium sulfate would mean you would need to add 10 ml of saturated ammonium sulfate (SAS):

* Chill in ice-water for 20 minutes.
* Spin 15 minutes in cold at a minimum of 13,000g (probably better to use the high speed centrifuge at 14,000 rpm which is 23,600g).
* Remove supe (and save if desired).
* Resuspend pellet in relevant solvent.

Sometimes we precipitate using less than 80% solution.
A reference with information about ammonium sulfate precipitations is in the binder.

Alternatively, to fit in a microfuge tube:

* Take 300 µl supe + 1200 µl saturated ammonium sulfate and ice 20 minutes.
* Spin 15 minutes at maximum speed of microcentrifuge.
* Remove supe. Resuspend pellet in relevant solvent. (Of course, if you know you can precipitate your protein with less than 80% ammonium sulfate, then you can accommodate more of the sample into the tube.)

TO MAKE A SOLUTION 20% IN AMMONIUM SULFATE (FROM 100% STOCK) ADD 0.25 VOLUMES OF 100% AMMONIUM SULFATE.

Here’s an example: Say you have 3 mls of a solution and want to make it 20% ammonium sulfate. The final volume will be 3 mls + x mls where x is the amount of ammonium sulfate you need to add.

Using:
(Final V) x (final C) = (V of concentrate added) x (concentrate C).

Then:
(3 + x) x (20%) = (x) x (100%)
60 + 20x = 100x
60 = 80x
x = 3/4 or 0.75 ml.
so, to bring a 3 ml volume to 20% ammonium sulfate you will need to add 0.75 mls of 100% concentrate.

TO MAKE A SOLUTION 40% IN AMMONIUM SULFATE (FROM 100% STOCK) ADD 0.67 VOLUMES OF 100%% AMMONIUM SULFATE.
(3 + x) x (40%) = (x) x (100%)
120 + 40x = 100x
120 = 60x
x = 2 mls (or 0.67 volumes).

TO MAKE A SOLUTION 67% IN AMMONIUM SULFATE (FROM 100% STOCK) ADD 2 VOLUMES OF 100% AMMONIUM SULFATE.
(3 + x) x (67%) = (x) x (100%)
200 + 67x = 100x
200 = 33x
x = 6 mls (or 2.0 volumes).

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Question by IQ: Organic solvents to break down plant fibers, safe to ingest?
I am looking for a solvent to break the fiber can be searched, such as in fruits and vegetables, which are very fibrous. This is for someone with a sensitive stomach, which can not tolerate the fiber, and it must be first a kind of pre-digested. Have a condition in which the fiber is put into the stomach, it must break down before consuming it werden.Würden better off with the use of digestive enzymes, or is there a good solvent to marinate food in the fibrous ?

Best answer:

Answer by daylily
Other than using a blender or food processor to pulverize the food, I’d stick with the digestive enzymes.

What do you think? Answer below!

Organic Chemistry: Introduction to the E2 mechanism. E2 stereochemistry – cis vs. trans, determined by antiperiplanar transition state. Protic vs aprotic solvents. SN2stereochemistry This is a recording of a tutoring session, published with permission of the student. These videos are offered on a “pay-what-you-like” basis. You can pay for the use of the videos on my website: www.freelance-teacher.com I offer tutoring via Skype. For more information, please visit my website to go. For the printable “handout” discussed in these videos, go to my website. For a playlist with all the videos in this series can be found here: www.youtube.com

Best answer:

Answer by Jabberwock
Amides can be hydrolyzed by sodium hydroxide. At low temp it would probably be slow.

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Question by psychiatrydude: Is molarity the moles of solute dissolved in one liter of solvent?
I thought it was moles of solute dissolved in one liter of solution. My chem teacher marked this problem wrong on my test, to tell the class that the solute is dissolved in one liter of solvent. Do you think she’s confusing it with molality or is that correct?

Best answer:

Answer by simonizer1218
Well, she isn’t confusing it with molality, because that’s 1 mole per Kg of solvent. Molarity is actually defined as moles of solute per 1 liter of SOLUTION. So, you would be correct, and she would be incorrect. How to go about telling your teacher she’s wrong is a another problem.

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