Saturday, March 31, 2012

Music about glucagon

Another Dr. Ahern's music (, this time based on the famous Christmas song Santa Claus is coming to town.


Glucagon is Coming Around

Instructor sings
You've gotta admire
What molecules do
Their cellular fire
Is ready on cue
Glucagon is coming around

Whenever it binds
Receptor outside
G protein finds
G nucleotides
Glucagon is coming around

Everyone sings
They activate cyclases
That make cAMPs
Which bind to protein kinases
And pull the R's from C's

Instructor sings
The glycogen shrinks
In liver quite fast
The glucose into
The bloodstream is passed
Thanks to this you have energy

Your muscles uptake
The glucose in turn
Obtaining a substrate
That all of them burn
Thanks to this you have energy

Everyone sings
The pool of phosphatidyl
Inositides in you
Can send two separate signals
When they get split in two

Instructor sings
The IP3 sets
The calcium free
Turning on
Protein Kinase C
And it happens so easily

The muscles contract
When calcium's free
Lowering levels
Of Creatine-P
And it happens so easily

Everyone sings
Those little calcium ions
I hope you've learned them well
Are just like Martha Stewart
All locked up in a cell

Instructor sings
This story's complete
I know it's a load
My hope is your head
Ain't gonna explode
You will really need it next week

Monday, March 26, 2012

Famous sentence (8)

However many ways there may be of being alife, it is certain that there are
vastly more ways of being dead.

Sunday, March 11, 2012

Regulation of pyruvate oxidation (part 2)

The pyruvate dehydrogenase complex activity is regulated mainly by two distinct mechanisms – allosteric mechanisms and reversible covalent modification.

In fact, there are some allosteric modulators of the complex, which in this particular case belong to the class of negative modulators, ie, inhibitors of its catalytic activity:
- Acetyl-CoA – it is the product of the reaction, thus, it makes sense that the molecule of acetyl-CoA has an inhibitory effect on its own synthesis
- NADH – one of the products of the reaction is NADH, so the reasoning is equivalent to that carried over to the acetyl-CoA molecule. Furthermore, as already mentioned in other posts of this blog, NADH may be involved in ATP synthesis (in cellular respiration), so, its presence indicates a potential for a high energy state into the cell. Accordingly, and as the oxidation of pyruvate to acetyl-CoA is part of catabolism, whose main objective is to obtain energy, it makes sense that NADH inhibits catabolism and, in particular, this reaction.

Regarding the reversible covalent modification, this enzyme complex is inhibited by phosphorylation and activated by dephosphorylation. This process is mediated by two different enzymes… The one that phosphorylates is called pyruvate dehydrogenase kinase, whereas the one that dephosphorylates it is the pyruvate dehydrogenase phosphatase.
Factors that activate the kinase, leading to the phosphorylation of pyruvate dehydrogenase complex (ie, inhibitors of its catalytic activity):
- Acetyl-CoA and NADH – in addition to its direct effects on the pyruvate dehydrogenase complex, as allosteric inhibitors, these two molecules also trigger the phosphorylation of the complex, promoting its inhibition, which means that they can act, therefore, through two distinct mechanisms

Factors that inhibit the kinase, favoring the balance towards the dephosphorylated form of pyruvate dehydrogenase complex (ie, activating its catalytic activity):
- NAD+ – for this molecule it can be done the reverse rationale made for NADH. That is, the presence of NAD+ indicates an energy deficit on the cell, so it is needed to activate the catabolism to counteract this deficit.
- ADP – the reasoning is equivalent to the one mentioned above, as to say that the cell is accumulating ADP means that it is spending ATP. Thus, it will need to produce again ATP
- Pyruvate – pyruvate is the substrate of the reaction, and its presence will activate the pyruvate dehydrogenase complex by inhibiting the phosphorylation process (and thus its inhibition) of the pyruvate dehydrogenase complex
- Coenzyme A (CoA) – this cofactor plays a co-substrate role, so that its presence will affect catalytic activity of the complex in a similar manner to that described for pyruvate

Factors that activate the phosphatase, leading to dephosphorylation of pyruvate dehydrogenase complex (ie, activating its catalytic activity):
- Ca2+ - calcium ion is an important modulator of the metabolism. In this particular case, this ion acts (in the muscle) at the level of pyruvate dehydrogenase phosphatase, activating it (by promoting its dephosphorylation). Put simply, the calcium ion is an indicator of muscle contraction, so it makes perfect sense that in the context of working muscles, the catabolism becomes active, so that there is ATP available for the process

Thursday, March 8, 2012

Music about prostaglandins

The song Oklahoma! has inspired Dr. Ahern ( to create a music about prostaglandins... :)


The ei-co-sa-noids creating pain
Are the ones to blame - when you get inflamed
And ouch(!) - they hurt inside your brain

Every throb and ache gets magnified
If you hope to win, cyclo-oxygen's
Generation's got to be denied

The Vioxx has all been recalled
So go get yourself Tylenol-ed
And if you aaaaaaaaaaaaache
Blame PGH synthaaaaaaaaase!

We must complain that
You make the aches prostaglandins
Prostaglandin - D2, F1, G2, E2
Prostaglandin, it's you

Saturday, March 3, 2012

Scientific jokes (12)

What is the sound that an atom makes when it burks?

And when it falls in the ground?