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Calculating the PI of a peptide question.

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Calculating the PI of a peptide question.

Postby BioNoob » Thu Apr 29, 2010 2:52 am

I am having trouble calculating the pi of peptide consisting multiple amino acid groups with the pH of 7.0.

The sequence is A-P-C-K-R, and the net charge I solved was +2

The pka values are
N-terminal 7.4
C- 8.3
K- 10.5
R- 12.5
C-terminal 3.6

The PI= 9.4 but I don't understand. Please help me...
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Postby JackBean » Thu Apr 29, 2010 6:33 am

I think, that the pI is just average of pIs of AAs, isn't it?

pI of COOH is 3.6? I thought it's about 2...
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Re: Calculating the PI of a peptide question.

Postby BioNoob » Thu Apr 29, 2010 6:45 am

It says that C-terminal carboxyl group for oligopeptide is 3.6
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Re: Calculating the PI of a peptide question.

Postby BioNoob » Thu Apr 29, 2010 6:58 pm

Ladies and gentlemen, I have finally solved the puzzle.
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