Thursday, 5th January '06

The Great Dehydrogenase Research Paper
(a.k.a. why us Rice People eat rice, not beer)

While Tzo researches restaurants, I research enzymes, it seems. In any case, the following is a product of:
- 4 months in Halifax watching Caucasians from North America / Oceania / Europe drinking their faces off,
- the ensuing shock-factor,
- the sudden meeting up with Singaporeans again in NYC,
- the resulting REVERSE shock-factor (read: Kiat's dreadful reactions to the first Coronas he bought in the USA. It was really quite frightening, I was honestly worried about anaphylactic shock or at least something equally gruesome - but I have an active imagination.),
- Vicki and my eavesdropping on Dal students' alcohol conversations on the Airporter,
- a Thursday afternoon without school,
- the complete lack of incentive to read for Secured Transactions tomorrow,
- a sudden urge that all those years of Biology and Organic Chemistry should not go to waste (though it HAS been a while since I was Bio and Chem Special Paper material, if ever, so please forgive the mistakes), and
- a Henghwa who is telling me that I'm mad for actually reading up on this and whom I will therefore spite by actually finishing this research.

Anyways, Tzo and I and someone else got into a wonderfully vague discussion about this in New York... and neither of us remembered what the enzymes were. And we just sort of assumed that the Asian lack of disposition to drinking was because we couldn't break down the alcohol. Actually that's not really true. But whatever it is, by the end of this we'll all have a genetic excuse to counter angmohs nagging about our "un-fun-ness".

By the way, I prefer to use the kind of IUPAC nomenclature we learnt for Organic Chem in JC, so the more common names I put in brackets behind. So here it goes:

The breakdown of alcohol, or more specifically, ethanol, occurs with the aid of a number of dehydrogenase enzymes. The first step in the breakdown is catalysed by a group of enzymes called alcohol dehydrogenases:

C2H5OH + NAD+ → CH3CHO + NADH + H+

Humans generally have at least 6 types of alcohol dehydrogenases, which exist in dimeric forms and are held in the stomach and liver linings. (The pictures are rather pretty, with all those nice alpha-coils in the proteins, heh). Each dimer contains 2 Zn2+ ions which, one of which hangs out around the catalytic site and encourages binding of the hydroxyl group in the ethanol, and thereby accelerates the reaction.
--> This paragraph is me being nerdy and giving a kitchen-sink answer, please ignore me.

The intermediate product (ignore the proton and NADH) is ethanal ("acetaldehyde"), which is further oxidised to ethanoic ("acetic") acid. This reaction is catalysed by acetaldehyde dehydrogenase, and also produces some other harmless molecules which I can't be arsed to properly work into the equation (NADH and H+, mostly, and some acetyl-CoA somewhere):


And I don't really know how the ethanoic acid is removed from the body. I'm going to assume for my current purpose that the ethanoic acid isn't going to give me or my liver any problems. It's just vinegar, after all.

So that's all fine and dandy. If everything goes according to plan. But if too much ethanol is going in at once, the acetaldehyde dehydrogenases don't quite seem to work as quickly as the alcohol dehydrgenases. This leads to an accumulation of ethanal in the blood stream. Ethanal, unfortunately, is far more toxic than the un-metabolised ethanol. And this results in one heck of a hangover. How cool. Hungover people can now say they have "ethanal poisoning" and make it sound somewhat legitimate.

And where does the Rice People part come in, you ask. Right about now, because of 2 little complications:

1. Alcohol dehydrogenases are particularly active in Asians. I haven't come across any reason for this, but I'll hazard a wild guess that it has something to do with a higher concentration of Zn2+ ions. Maybe our diet or something, I dunno. I could be very very wrong. What this essentially means is that we produce ethanal faster than then angmohs.

2. A gene mutation common in people of far-Eastern descent (Chinese and Japanese) results in the production of some screwed-up proteins. I say this figuratively, we all know that these globular proteins are ALWAYS literally screwed up. (As Mr Yap would say, the MolecuBes are Seepharicall. Heh. I miss Mr Yap.) But digression aside, this results in some screwed-up acetaldehyde dehydrogenases. They just don't work all that well. What this means is that we keep the ethanal around inside of us longer than the average angmohs.

So in summary:
Extra fast production of ethanal + extra slow removal of ethanal = a mother-lot of ethanal

Recall from above that ethanal causes hangover symptoms. When your body works like a Rice Person's, you can get so much ethanal in you so quickly after drinking that you get Severe and Immediate Hangover Symptoms. Such include a rapid increase in blood flow to the skin of the face, neck, and chest, rapid heartbeat, headache, nausea, and extreme drowsiness, otherwise recognisable as the "Kiat Chuan Reaction".

hehe Sorry Kiat. You were half the inspiration for this entry.

So that's why we never seem to get high / drunk in the fun, silly ways that the Caucasians do. Drunken fun comes from ethanol, but we don't retain ethanol very much. We go straight to retaining ethanal, which also means we go straight to being hungover. In more common parlance, we're allergic all the time. And my personal opinion is that this translates into the absence of a drinking culture. Tzo made an observation that it's no fun to drink when everytime someone starts, 40% of the people in the room abstain for allergic reasons. And then you learn to have fun without alcohol anyway. We're adaptable people wink. After a while its absence is completely not noticed - like at Kenneth's Alcoholess Christmas Party.

Except by Rice People who have lived in Halifax too long, it seems.

Poor Vicki.


[NB: references were mostly Wikipedia Organic Chem articles and a paper by the Indiana Alcohol Research Center]

en ying snapped a shot of life @ 04:49 pm
[10 photographs developed.]

10 photographs developed.




hey lay off vicki!
she doesn't HAVE to drink.
she's just surly otherwise.


OH MY GOD.... ryder.....


wow. now ryder visits too? *LOL8 sweet. *waves* hi ryder. I really have to meet you sometime ^^ vic has been gushing and gushing and...yep, still gushing. *LOL*


qiong's right. STILL GUSHING. if ryder can make her gush this much he has to be something, eh? please make sure i get a demonstration of the "face-rubbing-with-affection" at some point. big grin


actually there was eggnog at his party which is alcoholic. Marginally. ah haha affectionate face rubbing, ryder we all love your texts.


oh and thank you for the research, it was very enlightening!


jm simple the best and TRY Rocs lots of support from the netherlands keep up the good work see ya!!!


hey! hey! That was secret gushing! You're not supposed to tell him that!


umm. this blog isn't a john mayer affiliated thing, though i do love the music. still i agree, "try!" has some rocking guitar work. smile

and vic, you couldn't really expect us to keep the gushing secret, could you?

smile shocked sad
big grin razz *wink wink* hey baby
angry, grr blush confused
cool crazy cry
sleepy hehe LOL
plain jane rolls eyes satisfied