Monday, April 15, 2013

Monday's Molecule #202

The last Monday's Molecule was the pyrrolysine, 23rd amino acid. The winner was Michael Florea [Monday's Molecule #201].

Today's molecule is an enzyme. Homologous enzymes are found in all species. They play an essential role in metabolism. The green part binds the substrate and the subsequent reaction reduces a bound FAD prosthetic group (yellow). Electrons are then passed to an FAD molecule in the purple part in the orientation shown on the left. Notice that the yellow FAD molecules are close together. (The two purple parts on the left should be joined but the connection can't be resolved in the structure.) This electron transfer results in a shift in conformation to the conformation of the purple structure shown on the right. Note that the FAD molecule has shifted to a less exposed position. The purple protein then dissociates and carries electrons to an membrane-bound enzyme that transfers electrons to ubiquinol (QH2). Name the green protein and the purple protein.

This week I'm trying a new format in order to avoid moderating comments. Email your answers to me at: Monday's Molecule #202. I'll hold off posting your answers for 24 hours. The first one with the correct answer wins. I will only post mostly correct answers to avoid embarrassment. The winner will be treated to a free lunch.

There could be two winners. If the first correct answer isn't from an undergraduate student then I'll select a second winner from those undergraduates who post the correct answer. You will need to identify yourself as an undergraduate in order to win. (Put "undergraduate" at the bottom of your email message.)

Some past winners are from distant lands so their chances of taking up my offer of a free lunch are slim. (That's why I can afford to do this!)

In order to win you must post your correct name. Anonymous and pseudoanonymous commenters can't win the free lunch.

Winners will have to contact me by email to arrange a lunch date. Please try and beat the regular winners. Most of them live far away and I'll never get to take them to lunch. This makes me sad.

Comments are now open.

UPDATE: The enzyme is the medium chain acyl-CoA dehydrogenase (MCAD) (PDB 2AIT). The electron acceptor molecule with the FAD domain is electron transferring flavoprotein (ETF). MCAD catalyzes the oxidation of fatty acids leading to the release of a two carbon acetyl-CoA molecule and shorting the fatty acid chain by two carbons. This is part of the &beta-oxidation pathway. Nobody got the right answer

Winners
Nov. 2009: Jason Oakley, Alex Ling
Oct. 17: Bill Chaney, Roger Fan
Oct. 24: DK
Oct. 31: Joseph C. Somody
Nov. 7: Jason Oakley
Nov. 15: Thomas Ferraro, Vipulan Vigneswaran
Nov. 21: Vipulan Vigneswaran (honorary mention to Raul A. Félix de Sousa)
Nov. 28: Philip Rodger
Dec. 5: 凌嘉誠 (Alex Ling)
Dec. 12: Bill Chaney
Dec. 19: Joseph C. Somody
Jan. 9: Dima Klenchin
Jan. 23: David Schuller
Jan. 30: Peter Monaghan
Feb. 7: Thomas Ferraro, Charles Motraghi
Feb. 13: Joseph C. Somody
March 5: Albi Celaj
March 12: Bill Chaney, Raul A. Félix de Sousa
March 19: no winner
March 26: John Runnels, Raul A. Félix de Sousa
April 2: Sean Ridout
April 9: no winner
April 16: Raul A. Félix de Sousa
April 23: Dima Klenchin, Deena Allan
April 30: Sean Ridout
May 7: Matt McFarlane
May 14: no winner
May 21: no winner
May 29: Mike Hamilton, Dmitri Tchigvintsev
June 4: Bill Chaney, Matt McFarlane
June 18: Raul A. Félix de Sousa
June 25: Raul A. Félix de Sousa
July 2: Raul A. Félix de Sousa
July 16: Sean Ridout, William Grecia
July 23: Raul A. Félix de Sousa
July 30: Bill Chaney and Raul A. Félix de Sousa
Aug. 7: Raul A. Félix de Sousa
Aug. 13: Matt McFarlane
Aug. 20: Stephen Spiro
Aug. 27: Raul A. Félix de Sousa
Sept. 3: Matt McFarlane
Sept. 10: Matt Talarico
Sept. 17: no winner
Sept. 24: Mikkel Rasmussen
Oct. 1: John Runnels
Oct. 8: Raúl Mancera
Oct. 15: Raul A. Félix de Sousa
Oct. 22: Mikkel Rasmussen
Nov. 12: Seth Kasowitz, Bill Gunn
Nov. 19: Michael Rasmussen
Dec. 4: Paul Clapham, Jacob Troth
Dec. 10: Jacob Troth
Dec. 17: Bill Chaney, Dima Klenchin, Bill Gunn
Jan. 14: Evey Salara
Jan. 21: Piotr Gasiorowski
March 11: Bill Gunn, River Jiang
March 18: Bill Gunn
April 8: Michael Florea
April 15: no winner


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