[Mitch]

I assume the following mechanism occurs for the reaction of PCL-1 with hydrogen peroxide. The H2O2 decomposes to radicals which removed the B(OH)2 forming B(OH)3. But, I just don't know how or why the product is a ketone or how luciferin got separated from PCL-1. Any help would be appreciated.

Figure is from http://dx.doi.org/10.1073/pnas.1012864107

[azmanam]

So the oxidation steps of the typical anitmarkovnikov Brown hydroboration/oxidation goes as shown in attached image A.  Peroxide anion (not HO radical) attacks boron.  Alkyl migration (with loss of HO-), followed by basic hydrolysis gives the antimarkovnikov alcohol.

So by analogy, here's what I think might (might) be happening in vivo (attached image B).  Same attack of HOO-, alkyl migration, and hydrolysis gives a deprotonated phenol derivative.  The alkoxide anions collapse to form the C=O double bond, and kick out the O- on the opposite side of the ring.

Can't promise it's correct, but I can push the arrows to make it work.

[Mitch]

Thank you, you saved my hide. I was presenting this paper at journal club today and I just has a sense he would ask for the mechanism, because of you I was able to bust it out seamlessly. Thanks again.

Have you had a chance to read the paper at all? I'm just curious if you had any overall thoughts about it?

[azmanam]

Glad to help.  This seems like a clever way to measure peroxide levels.  Their comment about intra- versus intercellular H2O2 is an interesting one, though.  I don't know enough about the biology side to comment on the merits of the research, but chemically I like the use of the aryl boronic acid as a peroxide-labile protecting group.