00:01
Question number three is in reference to alanine and its two different pca values.
00:10
Turns out that alenine at its pi typically exists as a zyterion rather than as a neutral species.
00:21
Zwiterionic form is this one here where we've had an internal acid -based reaction with a hydrogen that was on the carboxylic acid group has been transferred to the amine group.
00:32
Rather than existing as this form here.
00:40
This occurs simply because the equilibrium constant for the acid -based reaction, the internal acid -based reaction is relatively large, shifting the equilibrium more towards the zyterionic form than this form here.
00:57
However, both forms are considered neutral, or at least a net neutral charge, but the zyterionic form has regions that are positively charged and regions that are negatively charged.
01:11
The textbook would describe this as the pi value is greater than the pca value of the carboxal group, and the pi is also less than the pca value of the amino group.
01:27
Because of this, there is a relatively large equilibrium constant that pushes the internal acid -based reaction to the right...