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Old 03-25-2012
johnvega98's Avatar
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Question Biochem question

After hydrolysis of the peptide bonds in a short polypeptide, the following amino acid was identified in a solution.

Nh2 ch cooh
ch2
ch2
ch2
ch2
nh2
if the ph of the solution is 7.4, which of the following is the most likely net charge of the pictured amino acid?

A. +2
b. +1
c. 0
d. -1
e. -2
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Old 03-25-2012
Hope2Pass's Avatar
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Thats a UW question. I remember doing that coz it stood out to me how much little detail this question went into!

The answer is B) +1

Source: net charge of amino acid

Explanation:
Quote:
Originally Posted by Meli View Post
You were correct in the first place, the answer is +1 because in physiological pH (7.4) the carboxyl and amino groups of an aminoacid are ionized (that means that COOH actually is COO- and NH2 is NH3+) for that there are three charges here are:
-1 for the terminal COO-
+1 for the terminal NH3
And +1 for the extra NH3 group

So the first two neutralize each other and the net charge is +1 because of the extra amino group. Which makes this a basic aminoacid (Lysine)

Hope I explained myself weel and helped you
Sorry if there are any typos. I'm writting this from my phone :P
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  #3  
Old 03-25-2012
johnvega98's Avatar
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yeah! lol! I dont quite get it though, but thats the answer. I post it to look for explanation other than the uworld.
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