I've run my 80% pure FMN on HPLC with fluorescent detector and I've seen at least six, maybe even nine peaks with the same exctitation/emission, as well as the same spectra on UV-VIS, so I pressume they are some derivatives of flavins. Three of them are obvious (and confirmed by standards) - FAD, FMN and riboflavin, but what could the other three (or even six) be?
Well, this is an old issue that might go back to the times of Hugo Theorell...
Which are the origins of your sample? (chemical synthesis? enzymatic degradation of FAD? extraction from biol. samples?).
How was the sample of FMN stored? pH, temperature, presence of proteins, buffers?
The Rib-5'-phosphate can move around at the ribityl side chain. See e.g. paper below and Refs therein.
In my experience it is not "worthwhile" following up on such an issue... Best could be (in my experience) to prepare a clean sample of FMN (e.g. by prep HPLC) and store it in the absence of high salt conc.
Eur J Biochem. 1976 Jul 15;66(3):567-77.
Synthesis, separation, identification and interconversion of riboflavin phosphates and their acetyl derivatives: a reinvestigation.
Scola-Nagelschneider G, Hemmerich P.
Hi Sandro, thanks for the answer.
I actually meant FMN purchased from Sigma. This one
http://www.sigmaaldrich.com/catalog/product/sigma/f6750?lang=en®ion=CZ
I thought they specify its origin, but unfortunately they don't.
It's more like I was curious, whether it could be some reduced forms, some radical or something alike?
No, for sure nothing like " some reduced forms, some radical or something alike"?
Well, if it contains also FAD, it's probably from biological source, right? Because how could organic synthesis introduce the adenine...
So they should be something that is contained in the living cell.
Biological source is probable.
However, the source is not necessarily the "living cell". You might extract FMN, FAD from cells, then when you convert FAD to FMN, extract, purify it etc. the phosphate might "wander around". See the paper by Nagelschneider & Hemmerich.
In your specific case it might be worth making SIGMA aware of this (send them elution profile + data). If they sell FMN it should be it, not junk. At least they should specify the purity. On the other hand you should be sure that you sample has not degraded "in your hands"...
It is sold as 80% purity, so based on the areas at 450 nm it is about right.
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