Monday, February 06, 2012

Monday's Molecule #158

This molecule is responsible for one of the distinguishing features of an entire group of species. Sadly, most undergraduates have never heard of this molecule and they never study the fundamental process that it represents. In my experience, about 90% of all introductory biochemistry courses skip the relevant chapter(s) in the textbooks. There's no reasonable excuse for that omission. It's just bad teaching.

Identify the molecule—the common name will do. Post your answer in the comments. I'll hold off releasing any comments for 24 hours. The first one with the correct answer wins. I will only post correct answers to avoid embarrassment.

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 comment.)

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.

UPDATE: The molecule is phycocyanobilin the light absorbing pigment in cyanobacteria (and some other species). This blue pigment is found in large structures called phycobilosomes and it is the reason why cyanobacteria were called blue-green algae. The winners are Thomas Ferraro and Charles Motraghi (undergraduate).

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


  1. Phycocyanin, the light-gathering molecule of cyanobacteria

  2. Phycocyanobilin, the terminal acceptor of energy for light-gathering structures of cyanobacteria

  3. Sorry for the multiple posts, but with a bit of research... I actually think Phycocyanobilin may be closer... but that seems to have an additional double bond...

  4. Unfortunatly I was never shown this structure in my 1st year Botany lectures, although we did learn about the molecule.

    The molecule is Phycocyanobilin, a tetrapyrole found in cyanobacteria.

  5. Oh, I forgot to mention, I am an Undergraduate...

  6. Phycoerythrobilin, a chromophore of phycoerythrin, pigment of all red algae.

  7. I don't know what the molecule is, but wonder if the diagram is correct. The C in the CH at the far right has only 3 bonds, not 4. Am I right, should it be CH2 or a double bond to the ring below?

    1. Is it phycocyanobilin, a phycobilin?

      My name is Charles Motraghi, I'm an undergraduate.

  8. It is phycocyanobilin from cyanobacteria, red algae and others.

  9. Dihydrophycocyanobilin is about the closest I can come up with.

  10. After a long search I could only find two compounds with trivial names that fit the basic "open porphyrin" tetrapyrrole structure containing an ethylidene group attached to ring A-carbon 3, and these are Phycoerythrobilin and Phycocyanobilin, but both contain two more hydrogen atoms, in different places. Accordingly, a good name for molecule # 158 would be 15, 16- Dihydrophycocyanobilin.
    These compounds are constituents of the light harvesting complexes of cyanobacteria and red algae.

  11. Phycocyanobilin, and an interesting use of my lunch time. I was chasing heme degradation products for a while.

    You may address me as the Plenipotentiary of Boredom!

  12. I will only post correct answers to avoid embarrassment.

    So that's just a lie?

    1. Sorry, my mistake.

      I deleted your incorrect answer so you won't be embarrassed. :-)