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I know PCR can be used to amplify a tiny sample of DNA in order to perform experiments. Is there a similar technique to use on a protein sample? More specifically, I'm not interested in "cutting" up the protein but simply making more of the original sample.

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  • $\begingroup$ You can't amplify proteins. You just have to express more and/or purify better. $\endgroup$ – canadianer Sep 10 '15 at 20:55
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    $\begingroup$ You can use in-vitro translation kits but they require mRNA as a template and the amplification is not exponential as in PCR. There is no biological mechanism to synthesize proteins using themselves as a template. This is unlike the DNA and RNA. $\endgroup$ – WYSIWYG Sep 10 '15 at 20:55
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    $\begingroup$ PCR takes advantage of the polymerase mechanism, which can build more nucleic acid from a template of nucleic acid. There's no such mechanism by which protein can be produced from a read of protein, as it's really the ribosome which produces protein from a nucleic acid template, right? As canadianer notes, you can only hope to express more, and purify it nicely! $\endgroup$ – CKM Sep 11 '15 at 21:29
  • $\begingroup$ Pull down the gene, make a cDNA and clone it into a high copy inducible expression vector. Transform bacteria or yeast and grow a culture under selection. Let them grow to 10^10 or more, then induce expression. Purify lots and lots of protein. If you can't get the gene, then you could undertake the very difficult task of sequencing the entire protein. Then you make a synthetic cDNA from the sequence and use that in your expression vector. You cannot get around the Central Dogma; DNA<->RNA->Protein $\endgroup$ – AMR Dec 1 '15 at 4:43
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There isn't any technique with one exception. PCR generates DNA from DNA so you can establish cycles. For protein synthesis, an mRNA is a template to produce proteins. Most likely proteins you are interested in would not synthesize mRNAs, so that you can not establish cycles.

The exception I said earlier is Protein Misfolding Cyclic Amplification (PMCA). Some disease associated misfold proteins can induce misfolding of the same polypeptide which is not misfolded. So you can establish cycles of misfolding reaction.

PS:

There are technique to synthesize proteins from DNAs or RNAs, but they are not chain reactions. https://www.promega.com/products/protein-expression/eukaryotic-cell-free-protein-expression/ https://www.neb.com/products/e6800-purexpress-invitro-protein-synthesis-kit

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It is impossible to amplify protein like PCR. DNA and RNA can undergo PCR because basepairs are complementary: A-T C-G A-U. But amino acids are not complementary; can you find an amino acid that matches glycine? Besides, proteins are not only a single polypeptide chain like DNA, proteins need to be folded after polypeptide chain are synthesized. Usually a protein molecule need more than one polypeptide chain to combine together to form a protein molecule. It can not happen that it works as PCR.

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I would say impossible is a stretch. An inventive biochemist could create molecules that are "complimentary" to each amino acid similar to a Dna polymerase. Then a protein would be needed to both detect and translate this similarity into protein elongation. Unlikely, hell yes, impossible, no.

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  • $\begingroup$ -1. There is literally no known mechanism through which this can be carried out. Designing functional proteins de novo is way out of reach of modern biochemistry. $\endgroup$ – March Ho Jan 30 '16 at 3:53
  • $\begingroup$ Even if you succeed in that process, the protein is still linear or worse. $\endgroup$ – A. Steiner Jan 30 '16 at 9:47
  • $\begingroup$ there multiple mechanisms for testing this methodology. Why would anyone initiate this process de novo? Evolution both in nature and the lab starts from a pre existing template. And all proteins are linear to begin with. $\endgroup$ – Vmon Jan 31 '16 at 20:18

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