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Enzyme activity & refrigirators; cool air,cells, & h

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Enzyme activity & refrigirators; cool air,cells, & h

Postby Host » Sun Mar 26, 2006 12:12 am

Alright, having just covered the chapter on ATP/enzyme activity in our text books this semester in cell i came upon a quest. our professor asked in class which has been bothering me ever since we started this chapter.

Ive read up on this subject (enzym. activity and refirg'es) yet still cant determine fully why we refrigarate food, while at point it can still go bad in such?

Take for instantance milk, (an experiment which i did)

I bought one gallon of 2% milk & one pint of "silk" soymilk and left them both UN-opened in my refrig. until approximetly 5 days after their experation date. Having opened them then (even with their seals never being broken) both of them had that all to common rancid smell w/ the soy even having chunks. They where both "spolied" and No taste test in this was needed to prove this "assumption"

Yet this occurs with other foods as well, which ive not specifically done as an experiement; i've left lettuce, tomatoes, grapes, yogart, noodles, and a whole plethera of other foods in there, most having closed air tight containers or having never been opened and they still go bad?

So relating this to enzym activity, how in the f* does this occur?

My deductions & research;
As we all know, enzymes make spontaneous (ie. exergonic) reactions occur almost 10k times faster by lowering thier activation energy, doing this by "induced fit" (active site ammino acids binding wealky to the substrate causing it to twist, while temporarily putting tension on it) with a result of;

substrate + enzyme -> enzyme substrate complex -> product +enzyme

This is where we get into the real **** though;\

Enzyme activity by my textbook and notes is thus defined as simply "substrate specificity" with the rate of enzyme activity under different conditions (velocitiy of reaction), with concentration being determined by gene expression.

COncentration as we know adversly affects activity b/c of enzym. saturation (constant enzyme concentration), having in turn our substrate against its product assocation...

Now relating this into turn to refrig's (ie temperature) we see that with too high a temp we denature the tertiary bonds and conformation falls apart, yet with too low a temp. theres not enough heat to drive enzyme catalyze reactions

Now relating all this to our food problem how does this occur? Why do we refirg. food and in turn why does the food still go bad?

If theres any "educated minds" here i'd really like to start a discussion on this, its pretty intresting to me that i cant figure out this puzzle with everything that ive read up on it, i'll post more as it comes

Host [/b]
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Postby Host » Sun Mar 26, 2006 12:26 am

ha ha i forgot the main thing, my hypoth.

alrighty, heres we go

My belief is that w/ refirges, were keeping temp constant, while at point reducing any denaturing/lack of catalystic reactions, keeping in turn enzym. saturation (ie. activity, remember concentration affects activity) unchanged so that there is a constant enzym. concentration and no substarte vs. its product assocation. This in turn all translates to good wholesome, non rotting healthy food.

Yet with time, and of course obvious rippening (veggies/other products) the rate of enzyme activity under these conditons eventully speeds up casuing of the velocity of the reaction to in turn increase thus casuing decompoistion, here we see the all to common pattern of {(order -> disorder (choas) --> back to order (not in context w/ this/nor shown)}

Now i know that the enzym that casues plants to rippen (i forget its name) plays a part in this but shouldnt refrigiration slow it down enough to give almost a twice as long non-spolied life span? In reality it does b/c if u left milk out in the natural env. it spoils in 3 to 4 hours respecitively (depending on humitiy/ temp) yet how could this occur if its in a cool env. and never exposed (ie. lid never even broken) ?

This "feable and simple" answer i feel is very wrong and thats why i've proposed the ques. feel free to comment and tell me where ive gone wrong,

thanks
H
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Postby th1_rhs13 » Sun Mar 26, 2006 12:29 am

Well your grasp of enzyme kinetics seems somewhat adequete but flawed, your speculation of lowering temperature and an increased yield of products is flawed; the affinity of an enzymes active site can become compromised or an increase in reacing the active site. If you wish to actually find the collison rate of a paticular enzyme (There will be more than JUST one) look further into enzyme kinetics, and mearsure the pH level of your medium and use the Delta G rate equation. If anything the general rules is that with increased heat collision rates follow.Seriously their are many more methods that follow.

Also depending on what enzyme you specifically are trying to to scrutinize thier are no way generalize its transition site facilitation stage. My statement in short: your question is to broad, an array of activities occur. Enzyme kinetics, oxidation, atrophy, the list goes on and on.

PS: No antihistamines nor nyquil are present in my body, thus an apt post thourughly eloborated.
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Postby kiekyon » Sun Mar 26, 2006 8:40 am

Host wrote:
Now i know that the enzym that casues plants to rippen (i forget its name) plays a part in this


ethylene??
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Postby th1_rhs13 » Sun Mar 26, 2006 9:14 am

I have proven myself to be far from adept in Botany, but that's a hormone, not an enzyme.
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Postby MrMistery » Sun Mar 26, 2006 10:01 am

The signal transduction pathway that causes fruits to rippen is composed of many enzymes. Ethylene(IUPAC ethene) activates the pathway and thus acts as a plant hormone. Studies show major problems for trees living near busy streets in big cities, as the ethene produced by the cars will interfere with their natural paterns...
Just wanted to tell everyone about the misteries of plants..
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Postby th1_rhs13 » Sun Mar 26, 2006 11:09 am

Indeed. Quite the perplexing topic, for me anyway.

By the way; 'Mystery' is spelled with a 'y' not an 'i.'
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Postby Host » Sun Mar 26, 2006 7:10 pm

concerning ph now, iv'e found that in humans we wish to keep constant an optimal level around six to eight, doing so by the trypsin/pepsin activity optima, yet in getting into temp and ph...enzyme inhibitors come into play in turn screwing up the normal components of metabolism, like MR. Mystery said --- such environmental contaminants screw everything up

Yet in a closed and regulated system (Ie.refrig) this is of no concern

can any one elaborate more on this topic who know more about it than i, ive searched the net but cant really find anything more on it...

and im not really needing to branch out into enzyme kinetics, im basically just trying to keep this as simplistic as possible within the confides of enzym. activity (being in turn substarte specificty, concentration (enzyme saturation) and temp (ph i guess could go in but does it reeally need too?)

thanks
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Postby MrMistery » Sun Mar 26, 2006 7:25 pm

@th1_rhs13
I know how it is spelled. It's just that 6-7 years ago when i first chatting on mIRC the nick MrMystery was taken. So i took MrMistery. And then it became my nickname and i don't wanna change it, even if it is spelled wrong...
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Postby th1_rhs13 » Mon Mar 27, 2006 5:29 am

I spoke in regards to 'misteries of plant.' But ok.

Host: Sorry decomposition can not just be concisely described, much less by a biologist. Best of luck in your endeavour.
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Postby MrMistery » Mon Mar 27, 2006 5:51 pm

Oh yes sorry. I make type-os all the time :D
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