## Search found 7 matches

Thu Oct 02, 2008 2:51 am
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461
NH3+---KAPRM---COO- K=Lysine has a charged R group A=ALanine nonpolar so not charged P=Proline (nonpolar) so not charged R=Arginine R group positive) M=nonpolar using this formula log[COO-]\[COOH]=pH-pK or log[NH2]\[NH3+]=pH-PK the alpha amino group has a charge of +1 based on the above formula Lysi...
Wed Oct 01, 2008 2:34 am
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461
I've been trying to solve the last question for a couple of hours and I got a net charge of -4 which is wrong. Can someone please help me with this problem?
Tue Sep 30, 2008 3:19 pm
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461
So, how would you find the net charge of a peptide such as MARSA at ph of 99?
Tue Sep 30, 2008 3:32 am
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461
Something is not right because none of the answers are 0. So the net charge of alanine based on the information I gave cannot be zero. I'm missing something.

What am I missing? Don't you use the Henderson Hasselbach equation somehow to calculate the net charge?
Tue Sep 30, 2008 1:44 am
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461

### Re: Finding the net charge of amino acid

Does this mean that based on the information I gave, the net charge of alanine at pH=8 is (+1) from alpha amino group plus (-1) from alpha carboxyl group which is equal to 0. (+1)+(-1)=0. Is this correct?
Mon Sep 29, 2008 11:01 pm
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461

### Re: Finding the net charge of amino acid

For the alpha amino group since pka>pH the charge would be +1. For the alpha carboxyl group since the pKa<pH the charge would be -1. I'm confused what to do with the pKA(s) of the side chain groups??
Mon Sep 29, 2008 8:28 pm
Forum: Molecular Biology
Topic: Finding the net charge of amino acid
Replies: 19
Views: 68461

### Finding the net charge of amino acid

How do you calculate the the net charge of glutamate amino acid at a pH of 99