2 TBR Ochem Typos/Mistakes (I'm pretty sure)

[justadream]

TBR Ochem page 215 #64

“Tyrosine best separates from cysteine at a pH equal to”

1. the pKa of Cysteine when using ether/water extraction
2. the pKa of tyrosine when using ether/water extraction
3. 7.0 when using ether/water extraction
4. Either pI of Cysteine or pI of tyrosine when using ether/water extraction

TBR completely drops the ball on this question and their answer key discusses LYSINE and tyrosine. From reading the answer, it seems like they suggest though that choice D is correct.

However, they also hint that one of the choices in A or B could be better (based on water solubility).


So what’s the real answer here?



TBR Ochem page 206 #9

The values the answer key uses do not match with the values given in the table. In addition, the answer given in the explanation do not match with the letter choice.


I put C because the reverse of the reaction with (H3C)NH has a Keq of 1/30 = .03.



Can someone confirm whether that is correct?

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