Organic pathways

[breadkay]

if it said in WATER...(therefore a zwitterion?)
then would you or would you NOT ionise the NH2?

No you would not ionize the Z group. The whole point of a zwitterion is that the whole molecule is neutral (no net charge). So, changing the charge of the Z group would defeat the definition

[jenny2012]

can someone PLEASE give me a definite answer on this, im so confused...

If the question is....

Draw asparagine in a solution with ph2
(therefore acidic)
you WOULD ionise the Z group and make NH2 become NH3

HOWEVER...

if it said in WATER...(therefore a zwitterion?)
then would you or would you NOT ionise the NH2?

Im pretty sure it doesnt because a zwitterion should be neutral

[jasoN-]

Asparagine has an amide group, which is not basic nor acidic.
It does not ionise (the side group), so it is a zwitterion at neutral pH

[destain]

ok thank you, everyones been saying different things and so have the practice exams...

SO to finish this off....
IN water, protonate and deprotonate the main chain and LEAVE the side group alone no matter what amino acid it is...

and in acid and basic solution, protonate and depronate ALL NH2 and COOH whether in side group or main chain?

[ligands]

destain have you got this?

http://www.atarnotes.com/?p=notes&a=feedback&id=94

[diligent18]

can someone PLEASE give me a definite answer on this, im so confused...

If the question is....

Draw asparagine in a solution with ph2
(therefore acidic)
you WOULD ionise the Z group and make NH2 become NH3

HOWEVER...

if it said in WATER...(therefore a zwitterion?)
then would you or would you NOT ionise the NH2?

It will be ionised! 
I know everyone is claiming that it will be contradictory to the definition of it being 'neutral', but the zwitterion with its ionised side chain WILL be neutral at its ISOELECTRIC point.

[destain]

is this on vcaa exams LOL

[halfbloodprincess]

Water has a neutral pH, but each amino acid will have its own isoelectric point...  the pH of water (7) may either be above or below this point and so water can be either an acidic or basic environment in relation to the amino acid. So if the isoelectric point of an amino acid with an amine group in its Z group is 8, and it's placed in water, both its amine groups will be protonated.

[halfbloodprincess]

can someone PLEASE give me a definite answer on this, im so confused...

If the question is....

Draw asparagine in a solution with ph2
(therefore acidic)
you WOULD ionise the Z group and make NH2 become NH3

HOWEVER...

if it said in WATER...(therefore a zwitterion?)
then would you or would you NOT ionise the NH2?

It will be ionised! 
I know everyone is claiming that it will be contradictory to the definition of it being 'neutral', but the zwitterion with its ionised side chain WILL be neutral at its ISOELECTRIC point.

I'm pretty sure the zwitterion won't have an ionised Z group

[Destiny]

Ok.  My teacher said NOT to ionise the side chain in the zwitterion.  My tutor said TO ionise the side chain zwitterion.  They're both examiners, what should we do.....!!!

[destain]

exactly eveyone has been saying different stufff

[soccerboi]

With zwitterions, don't ionise the Z group, just the amine and carboxyl on the main chain. Only when it's in basic or acidic solutions, you should ionise the z group(any NH2 in the z group becomes NH3+ in acidic solution and any COOH in the z group becomes COO- in basic solution).

[aznxD]

The side groups of the zwitterion is not be ionised. Zwitterions are dipolar hence have no net charge. Amino acids such as Aspartic acid and Glutamic acid will have low isoelectronic point, hence exist in it's neutral form (zwitterion) in more acidic conditions so that the extra -ve charged is neutralised. However when Aspartic acid and Glutamic acid are dissolved in water of pH 7, it is well above it's isoelectric point, hence the side group will be deprotonated.

[Destiny]

Asparagine has an amide group, which is not basic nor acidic.
It does not ionise (the side group), so it is a zwitterion at neutral pH

Erm, it came up in my SAC and I'm pretty sure that in an acidic environment the NH2 groups ionise to NH3+ so it has two positive charges and migrates

[aznxD]

Asparagine has an amide group, which is not basic nor acidic.
It does not ionise (the side group), so it is a zwitterion at neutral pH

Erm, it came up in my SAC and I'm pretty sure that in an acidic environment the NH2 groups ionise to NH3+ so it has two positive charges and migrates

No, as Jason said, Asparagine has an amide group which do not display acidic or basic behavior.