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Wednesday, December 14, 2011

Monday's Molecule #153

Today's1 molecule has a special significance for me since I "accidentally" purified the enzyme that catalyzes the last step in its synthesis. That was one of my first successful experiments as a graduate student (1969).

This is a complex molecule so I'm not going to insist on the IUPAC name. You can supply a common name as long as it is unambiguous (be careful!). This time it's not sufficient to just give me the name of the molecule. You also have to briefly explain what it does and where you can find it, including the "species." The functional explanation has to be a biochemical explanation.

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.) Every undergraduate who posts a correct answer will have their names entered in a Christmas draw. The winner gets a free autographed copy of my book! (One entry per week. If you post a correct answer every week you will have ten chances to win.)

After today, you have only one more chance to win an autographed book.

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 β-D-glucopyranosyl-5-hydroxymethylcytosine. This is a modified base found in T4 bacteriophage and its relatives. The modification is required to protect phage DNA from E. coli host restriction endonucleases.

The winner is Bill Chaney.

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)

1. Yes, I know it's Wednesday. I was too busy on Monday to post a molecule.


  1. Larry-

    The molecule is beta-glucosyl-5-hydroxymethylcytosine.

    The "species" it is found in is T4 bacteriophage.

    It is the product of a beta-glucosyltransferase utilizing UDP-glucose as a substrate to transfer glucose to hydroxymethylcytosine (formed from cytosine) in the T4 DNA to enable it to evade host restriction nuclease enzyme attack.

    Best wishes,
    Bill Chaney

  2. I think the molecule is (beta)-L-glucosyl-5-hydroxymethylcytosine.

    The enzyme is DNA beta-glucosyltransferase. Functionally, it transfers the glucose from uridine diphosphoglucose to 5-hydroxymethylcytosine in T4 phage DNA.

    It's found in the DNA of T4 bacteriophage, where it protects the phage DNA from phage and host derived nucleases (restriction endonucleases)

  3. I believe the molecule is beta-glucosyl-5-hydroxymethylcytosine. It is found in Enterobacteria phage T4, also known as bacteriophage T4.

    The enzyme DNA beta-glucosyltransferase catalyzes the transfer of glucose from UDP-glucose to 5-hydroxymethylcytosine (present in phage DNA in place of cytosine) in the double-stranded DNA of the T4 phage. This prevents restriction endonucleases found in its host (E. coli) from recognizing its DNA (at a restriction site containing the glucosylated base) and cleaving it.

    -Jason Oakley

  4. Molecule #153 is 5-gmC, or β-glycosyl-5-hydroxymethylcytosine, or β-D-glucopyranosyl-6-amino-5-(hydroxymethyl)-1H-pyrimidin-2-one.
    It is also the glucoside of 5-hydroxymethylcytosine (5-hmC), found in mammalian cells, especially in the central nervous system, and whose presence in the genome has been associated with gene activation and epigenetics.

  5. glc-HMC. It makes T4 phage resistant to E. coli restriction enzymes, though this has been overcome by gmrSD, which is in turn overcome by IPI*.

  6. The structure is a beta-glucosylated hydroxymethylcytosine. Bacteriophage T4 beta-glucosyltransferase tacks on a glucosyl residue on the -OH group of the hydroxymethylC. When found in DNA, this modification of 5-OH-methylC confers resistance of DNA specific nucleases