Guess I owe that doctor an apology.
rick barclay
Oh, and btw, he WASN'T treating me for HIV.
We should correct genetic disorders and create smarter, stronger humans.
We should correct genetic disorders, but not try to create better humans.
We should not alter human genetic makeup at all.
Guess I owe that doctor an apology.
rick barclay
Oh, and btw, he WASN'T treating me for HIV.
No. Wait. Don't hang up!
This is America calling!
The V:
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the R (+) form of the enantiomer, which is the medicinal form, it would equilibrate to 50% each of the R (+) and S (-) forms in the blood
<<<
So you are saying here that the enantiomorphs can exchange their chirality? That, frankly, suprises me, and interests me enormously. Do you have a url where I can read more on this?
Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.
MANY enantiomer pairs exhibit this.
In thalidomide, it happens because one of the 4 components of the chiral carbon is a hydrogen atom. Further, because the chiral carbon is adjacent (alpha) to a ketone group, this hydrogen is somewhat acidic. In other words, the anion is stabilized by a resonance structure in which the negative charge is on the oxygen atom of the ketone. Oxygen, being an electronegative atom, accepts a negative charge better than carbon; this resonance structure makes the alpha hydrogen much more acidic than it would otherwise be, acidic enough that the molecule can dissociate into H+ and a carbanion without the presence of a strong base. This is true of any hydrogen alpha to a carbonyl group, in fact.
When it dissociates, the carbon changes from an sp3 hybridized carbon to an sp2 hybridized carbanion (the nonbonded electrons now occupy a p-orbital). The chirality is lost -- the geometry of this carbon is now trigonal-planar, not tetrahedral. It will quickly pick up a hydrogen again (it's acidic enough to lose this hydrogen, but not acidic enough to remain in this state for very long, except in a moderate to strong basic solution). When it picks the hydrogen up again, the hydrogen has equal chance of "attacking" the carbanion at either face; thus there is a 50% chance that the carbon will assume the R configuration, and 50% that it will become S. Over time, this dissociation and recombination will cause the enantiomers to equilibrate as the racemate.
Racemization is very common in chiral molecules where one of the 4 substituants is hydrogen, and the hydrogen is acidic because of neighboring atoms. There are other means of racemization, but all of them generally follow the same idea: they convert a chiral atom into one which is not chiral by altering the bonds to that atom. When the reaction is reversed, there is equal chance of creating either enantiomer.
Last edited by The V.; 12-01-2001 at 04:46 PM.
BTW, this is the reaction that racemizes thalidomide. Stereochemistry at the chiral carbon is shown, as are both relevant resonance forms of the planar intermediate.
Sorry for the crummy quality, I don't have a good organic formula package anymore, so i borrowed and modified an image I found.
Also (although my organic prof would've marked it off) I only included the unpaired electrons that we care about -- obviously, each oxygen should have 2 more pairs of electrons, and the nitrogens should have one more pair.
Last edited by The V.; 12-01-2001 at 04:36 PM.
I think that human gene manipulation is good for us (people), beacuse we can become better humans.
Current projects:
1) User Interface Development Kit (C++)
2) HTML SDK (C++)
3) Classes (C++)
4) INI Editor (Delphi)
Regardless of our current ability to modify embryos it will soon be an available service.
Over 40% of parents said they would use the service to increase their child's IQ or to remove disabilities.
These kinds of percentages are a green light as far as marketing is concerned.
As we all know the world is driven by the dollar, not by morals, and there are big bucks to be made here.
"Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
Friedrich Nietzsche
"I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
George Best
"If you are going through hell....keep going."
Winston Churchill
That's why people are getting greedier and greedier so worse and worse.
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322reenignE
Yoshi
The V.:
Thanks for your explanation and graphic. I am currently sitting at my desk looking at the structural formula of Meclizine and wondering about the chiral centre there. One component is H, and there is an adjacent piperazine group which, presumably could lead to the same effect you described, (and described well I might add).
Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.
Genetic manipulation of humans for unpractical purposes!
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Engineer223
Yoshi