Friday, September 16, 2011

Music about fermentation

I like very much this music made by Dr. Ahern (www.davincipress.com/metabmelodies.html)... :)
It is about fermentation and is based in the famous Oh Susannah!

Here it is the link to download it:
http://www.mediafire.com/?zhbfbz91u70ca10


Oh, late last night I went to jog
when everything was still
I came upon a gravel road
a-windin’ up the hill
I don’t know why I did it but
I played a game with death
Ran up that hill in double time
And held in all my breath

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP

‘bout half way up I felt the burn
My hip down to my knee
if only I had stayed awake
In biochemistry
then I’d have had a warning, but
regrets were just too late
I stood in pain - my body was
reducing pyruvate!

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP
Well up came my professor who
was trailin’ close behind
he told me how fermenting was
a process most unkind
Oh ATP is energy
It’s keeping you alive
It’s mostly made by protons mov- ing
through the complex five

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP

In making ATP a pro- ton gradient is key
to ADP’s phosphoryla- tion, oxidatively
Electrons pass through complex four
And oxygen, you know
picks up four more electrons and

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP

I hope that you can clearly see
Exactly what I meant
That oxygen is needed for
The proton gra-di-ent
your muscles work in overdrive
And use up ATP
you might be breathin’ hard but lack sufficient energy
Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP

You’re in a heap o’ trouble and
this breath may be your last
if you can’t make some ATP
and NAD+ real fast
It’s lactate dehydrogenase
To save the day, you see
Turn pyruvate to lactate and
Produce more NAD+!

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP

The NAD+’s important,
Are You gettin’ all of this?
it gets fed back into the pathway
of glycolysis”
It hit my ear, it was so clear
and all made sense to me
Although I had no oxygen
I still made ATP

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP
For all he’d done I took my prof
to sit down for a drink
admitting that his lesson earlier
had made me think
I took a swig of ale
And grinning wide, I said with glee
Oh, fermentation hurts but all in all
It’s fine by me

Fermentation!
I need some NAD+
my cells are lackin’ oxygen
But using ATP
makes double H2O

Fermentation!

Wednesday, September 14, 2011

Video about the Krebs cycle (2)

Here it goes one more video about the Krebs cycle, this time in a karaoke version. :)

Tuesday, September 13, 2011

Scientific jokes (7)

Why do you should keep aboslute science in the laboratory?
To avoid that the reagents become unconcentrated.

Sunday, September 11, 2011

Friday, September 9, 2011

Krebs cycle (reactions) - part 1

Reaction 1: formation of citrate
This irreversible reaction is the 1st regulatory point of the Krebs cycle. It is a reaction in which an oxaloacetate molecule reacts with acetyl-CoA. In this process it is formed a very energetic intermediate (citroil-CoA) that rapidly converts into citrate. The molecule of CoA-SH liberated is recycled to participate in a new oxidative decarboxylation of pyruvate (catalyzed by pyruvate dehydrogenase complex).

Reaction 2: formation of isocitrate via cis-aconitate
This reaction occurs through the formation of an intermediate, cis-aconitate, obtained by dehydration of citrate. Thereafter, the cis-aconitate is hydrated, forming isocitrate. Thus, citrate and isocitrate are isomers. Despite that in cellular conditions the reaction produces only about 10% of isocitrate, the rapid consumption of this product in the following reaction shifts the equilibrium in the forward direction. The fluoroacetate is a toxic molecule because in physiological conditions it is transformed into fluoroacetil-CoA, which condenses with oxaloacetate to form fluorocitrate, that inhibits aconitase, causing accumulation of citrate.








Reaction 3: oxidation of isocitrate to α-ketoglutarate and CO2This reaction is an example of an irreversible oxidative decarboxylation, and it is the 2nd regulatory point in the Krebs cycle. In fact, this reaction is a set of three different reactions:
1. Dehydrogenation of isocitrate, creating oxalosuccinate and producing NADH.
2. Binding of Mn2+ to the carbonyl group of oxalosuccinate, stabilizing the enol and promoting the release of CO2.
3. Hydrogenation, with the arrangement of the resonance hybrid.





Reaction 4: Oxidation of α-ketoglutarate to succinyl-CoA and CO2This reaction, like the previous one, is another example of an irreversible oxidative decarboxylation. It is the 3rd (and the last one!) regulatory point of the Krebs cycle. This reaction is virtually identical to the oxidative decarboxylation of pyruvate, also leading to the formation of NADH. It is a very exergonic reaction due to the energy stored in the bond S-CoA.





Main bibliographic sources:
- Quintas A, Freire AP, Halpern MJ, Bioquímica - Organização Molecular da Vida, Lidel
- Nelson DL, Cox MM, Lehninger - Principles of Biochemistry, WH Freeman Publishers