Simple Protein Question

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thewax
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Simple Protein Question

Post by thewax » Wed Dec 24, 2008 10:44 pm

This is not a homework question: I was reading in Deborah Goldberg's AP Biology and when I was reading about the 1952 Hershey and Chase experiment, I got really confused.

In the same book: "Proteins consist of the elements S[ulfur], P[hosphorus], C[arbon], O[xygen], H[ydrogen], and N[itrogen]." But what are proteins made of? Amino Acids connected by peptide bonds (and of course, in the secondary and tertiary structures, various bonds - i.e. hydrogen bonds, ionic bonds, etc.). If you will carefully look at a chart of amino acids, you will notice that NONE contain the atom of Phosphorus. So is the book wrong when they say that proteins are made of phosphorus? Additional evidence is this passage excerpted from the same book: "They tagged bacteriophages with the radioactive isotopes 32P and 35S. Since proteins contain sulfur but not phosphorous and DNA contains phosphorous but not sulfur, the radioactive 32P labeled the DNA of the phage viruses while 35 S labeled the protein coat of the phage viruses."

blcr11
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Post by blcr11 » Thu Dec 25, 2008 12:26 pm

Phosphorus isn't a part of amino acids or proteins as they are made, but phosphorylation is a common post-translational change to proteins, especially as part of signal recognition or metabolic regulation. To be sure, most proteins in the cell do not contain phosphorus. But for those that do, it is important.

The tagging of bacteriophage you mention sounds like a discussion of the Hershey-Chase experiment to prove that the transforming principle was DNA and not protein. Not really relevant to the issue of whether P is found it proteins or not.

thewax
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Post by thewax » Thu Dec 25, 2008 11:13 pm

Thanks!!!!!!!! :)

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