Posted by chemist on June 21, 2004, at 11:15:55
In reply to Re: diference between phenylaline and phenylethylamine » chemist, posted by Larry Hoover on June 21, 2004, at 10:23:59
> > no, just wondering where that extra proton you need to saturate the alpha carbon would come from :)......all the best, chemist
>
> I studied enzyme kinetics, but it didn't much touch on stoichiometry....do carboxylases require protonation of the carboxyl(ate) moiety? Or are we simply exhibiting differing styles or expression?
>
> I tend to simplify for comprehension, then add detail/conditions later, as needed.
>
> Lar
>
i think our styles are just different, that's all...plus i was giving you a hard time about where the proton comes from, but if you decarboxylate at the alpha carbon, you do need to find a proton somewhere to saturate the carbon...but it depends on conditions, as the pKa of the proton in the COOH is about 2.2, and the pKa of the amino is 9.4 (i'm stealing from voet and voet). so, if the goal is to make a homomeric peptide, then all you're looking at are elimination reactions, and you never have to deal with actually removing the COO- from the alpha carbon. but if you want to get phenethylamine, you have to dump the COOH and replace with a proton (or, more reasonably, you have a cation salt of phenylalanine) and you can do this 2 ways: heat it up, and the COOH proton jumps to the alpa carbon and CO_{2} is lost; or, get involved with acetyl coenzyme A, thiamine, and pyruvate dehydrogenase.....more at ya later, chemist
poster:chemist
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