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Mad Scientist said on March 10th, 2009 at 3:59 pm

Mmmmm, my favourite female-shaped dessert — cellular peptide cake.

With mint frosting.

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karellan said on March 10th, 2009 at 4:26 pm

I was hoping for an ACTUAL biologist joke, rather than a Star Trek reference.

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NCallahan said on March 10th, 2009 at 4:35 pm

Well, that was a surprisingly uninformative but ego-filled article. I mean, it’s good, he came up with good cheap science and that’s good, but it exaggerates the impact of this — de novo polypeptide synthesis by classical organic methods is not universally relied upon and is, frankly, limited in application outside of the commercial sector. The great triumph here is that pharmaceutical companies can now mass produce ligands (short proteins that go in some drugs) with less pollution and that is great. But he hasn’t pulled one over on all of science.

Dick rubbing aside, I really wish this article had more meat to it — since water is already know to be an integral part of peptide bond synthesis. It’s a promising method and would like actually have it explained to me, rather than observe the internet equivalent of cackling maniacally.

But fuck you, MGK. There are no peptide jokes. Peptides are serious business. I spent my best college years obsessing over protein structure folding and I won’t have the sacrifice of my sex life belittled by the likes of you.

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But fuck you, MGK. There are no peptide jokes. Peptides are serious business. I spent my best college years obsessing over protein structure folding and I won’t have the sacrifice of my sex life belittled by the likes of you.

Certainly not. That’s why I asked my commenters to do it for me.

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NCallahan said on March 10th, 2009 at 4:51 pm

And this, ladies and gentlemen, is a PAC works.

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Perhaps someone could look at the actual article?

I don’t pretend to understand anything beyond 2nd year Chem.

There’s a link to the article on the right (pdf)

http://www.pnas.org/content/early/2009/02/26/0809052106.abstract

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Illuyankas said on March 10th, 2009 at 5:52 pm

What do you call an incoming mass of seawater that cheers you up?

A peptide!

…yes, I’m single, why do you ask?

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Pfft, I can make peptides from water. Hell, give me methane, ammonia, hydrogen and some radiation and in a couple of million years I’ll get you LIFE!

Anyway, that article explains nothing. I’m a biochemist and really, NCallahan is totally right, I’m unimpressed. I’ll try to read the PNAS paper tomorrow.

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But karellan, its such an awesome Star Trek reference, which in turn made for an even more awesome Tom Petty reference.

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NCallahan said on March 10th, 2009 at 11:18 pm

Okay, now to eat my words. This is significant. Not for the reasons the original article suggested — it’s a crap article.

Now, I can’t fully explain the chemistry here looking at the paper myself, because I’ve got only a limited grasp of organic chemistry. I know just enough o-chem to work with proteins and their catalytic sites, but direct organic synthesis is not something I’m well versed in; the paper references a lot of procedures that are probably well known in the community, but are just Greek to me. But with my limited education, I can say this. Back when I was doing undergrad, the most trustworthy method for creating a polypeptide was pellet dipping. You had your first peptide covalently bonded to a giant blob that you robotically moved from stock solution to stock solution, running the reaction for a dehydration bond in each one. Costly, cumbersome, and produced a bunch of leftover shit.

The method discovered allows one to alter the glycine at the end of a peptide chain as you desire, without altering any of the internal peptides. Glycine could be called the ’empty’ peptide. Where most peptides have a unique chemical group (the R group), glycine just has a hydrogen. This process replaces that hydrogen with a functional group and preps the polypeptide for a new glycine to be generated at the end. Why is this faster than the pellet method? Because you don’t have to protect the other end of the polypeptide. A dehydration reaction can occur at either the C or N terminal, but this process works at just the C terminal. Moreover, you can work with the smaller building blocks, instead of having solutions of whole peptides prepared before hand. I’m sure there’s still a reasonable amount of isolating and resoluting and going through stock solutions, but this would be faster and cheaper.

So, why significant? Well, we’ve got this big ol’ human genome we’re trying to figure out, right? Part of the problem is, even if we can point to the unique genes, we don’t necessarily know the proteins they code. Proteins can be modified after transcription/translation and a single gene can produce multiple proteins through intron splicing, so simply having the gene and knowing the genetic code doesn’t give you an accurate picture of the end product. We need to catalog the full human proteome, before can hope to get real work done on successful mapping human metabolism. (Just for fun, look up the current diagram of all known human metabolic processes, then tell yourself that this still only represents a sub-section of the entire picture.)

Protein identification means we have to capture proteins and pull them out of the cytosol, which means we need antibodies — short artificial peptide chains that bind to proteins and anchor them to whatever the antibody is attached to. Nearly all proteomic methods use antibodies and frequently, you have to purchase them from scientific supply companies, which can be time-consuming, expensive, and may not even give you ideal supplies to work with. A faster, cheaper process for creating peptides means you can get more experiments done in less time and with better customization.

Is this process really more ‘green’? You’ll need an organic chemist to answer that one. Even I can see the immediate advantage to a process that uses copper as a catalyst over palladium, but for me, environmental responsibility means you nuke the recombinant e.coli with bleach before you poor them down the drain.

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So are peptides the choice of this generation?

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See, this is why I could never be a scientist. I got less than halfway through NCallahan’s last post before my eyes crossed and I lost it.
I’ll just let someone smarter than me explain it as though I was back in high school. Thanks.

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Ok, as I see it, they’re not really creating peptides out of water, but modificating them very specifically. Not really functional proteins, neither, but short peptides (not that short peptides are not important or useful).

Now sure, this is a step forward that could cheapen (is that a word? not native english speaker so…) protein synthesis and, consequently, antibody production. But the ScienceDaily article is pretty misleading.

Mc’ed: Imagine a protein or polypeptide is, generally, a long sequence of letters. A peptide is a short one.

There’re a lot of methods to create a peptide, one letter at a time. This new method allows to change a letter in an existing peptide, changing the word.

Producing peptides is important for many reasons (eg. NCallahan mentions antibody generation), so it’s obviously good to have a cheaper, simpler, ecofriendlier way to do it.

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This is almost a chemistry joke…in that it deals with the general field of science I guess.

Two atoms run into each other. One atom says “I think I lost an electron.”
The second atom asks “Are you sure?”
The first atom replies “I’m positive.”

I also found some good ones here:
http://www.jupiterscientific.org/sciinfo/jokes/chemistryjokes.html
(many of which I don’t understand but laughed to keep up appearances)

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NCallahan: I got the gist of it, but have this compulsive need to simplify everything with a cheesy metaphor. How’s this for accuracy?

I want to paint my car. In order to do so, I need to mask all non-metal parts with paper, plastic and tape, which is time consuming and resource intensive. Now, someone comes along and invents a paint that only sticks to metal. Now I can paint my car by simply driving it through a spray room — making the whole process faster and cheaper.

Quayec: Cheapen is a word, and we all understood what you mean to say. However, cheapen usually is loaded with the negative meaning of “to devalue”, such as “Bill and Monica cheapened the Presidency.” You’re not incorrect, but “make protein synthesis cheaper” would be better.

And this is why English is tough. It’s not the grammar, its the subtle differences in meaning that arise out of usage rather than definition.
It’s also what makes English one of the richest languages on the planet.

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I want to bop piranhtachew over the head with a foam mallet.. that was terrible. Nostalgic, but terrible.

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I found this article about contouring arms with makeup http://onlinepersonalstylist.com/contouring-arms-with-makeup/

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