Succs to be me...

Dear Miss Metabolism,

I am a complex II, and I am being bullied. I work just as hard as any other enzyme complex, I contribute as much as I can, but the other complexes make fun of me because I can't pump protons like they do. Even Complex V teases me, and she lets protons back in!!!

How is that fair?

I can't control the redox potential of succinate or ubiquinone, any more than they can control the redox potentials of their substrates and products.

I wouldn't mind so much, but they're making my little FAD depressed. Sometimes I hear him crying himself to sleep at night. Its not right for a little prosthetic group to hear his enzyme being humilated like this, its bad for his self-esteem.

I've tried explaining these things to the other complexes, but they just won't listen!

Any advice on how to handle this?

Yours truly,
Succs To Be Me


Dear Succs To Be Me,

The first thing I want you to do is stop talking about yourself like that! You are an important complex, and don't ever forget it!

Its true that via Complex I, the electron transport chain can continue along without you, but there is more to a half-life than transporting electrons. Its true that you don't pump protons, but there is more to a half-life than generating electrochemical gradients.

Perhaps this sounds cliche, but I am pretty sure they are just jealous. Lets not forget that the succinate dehydrogenase part of you is absolutely integral to the citric acid cycle, and what would happen if you stopped functioning? I'd like to see them get much in the way of reducing power then, the supply would become pretty scarce, I can tell you!

And in addition to all that, you might have a role in oxygen sensing and tumour suppression too!

I wouldn't be surprised if Complex I was the one instigating all this, after all, you are the competition, and he probably sees you as a threat. As for Complex III and IV, they should be ashamed of themselves, how can they make fun of you while still accepting your electrons? They would do well to remember that the real reason they can pump protons is because of the difference in the reduction potentials of their substrates and products, and not because of any intrinsic property that they have.

And my sympathies to your little FAD, although we coddle and fuss over them, don't worry, prosthetic groups are alot tougher than we give them credit for, he'll be alright, as long as you don't take their insults to heart.

Having hopefully activated your self-esteem a little bit, let me just say this. Bullies are insecure, and they crave a response from those they bully. To paraphrase a human saying, 'Enzymes need substrates'. Show them just how much you don't care, and if they really get on your nerves, take a break for a while... when the citric acid cycle grinds to a halt, they'll be begging you to start transporting electrons again.

Keep your chin up,
Miss Metabolism