Mechanism of X-gal staining

Ben Murray bmurray at
Tue May 24 13:06:36 EST 1994

I'm looking for an easily-accessible source for information on the 
formation of the blue precipitate in X-gal staining using beta-
galactosidase (beyond the level of "the 5-bromo-4-chloro-3-indolyl 
group gets cleaved off and forms a blue precipitate").  Surprisingly,
I haven't been able to find this easily by looking through various 
methods books and staining papers or by talking to a few colleages. 
I've chased a few references back to the '70s, but before I dig them
up, I though I'd ask here if anyone knows of a methods book or something
that has this info in it.

Also, similar info on the mechanism of staining by the X-phosphate and 
nitroblue tetrazolium mix used for alkaline phosphatase staining also
would be appreciated.

This info is for an undergraduate laboratory course that I am developing.
I would like to be able to present to the students the mechanisms of the
reactions that they are observing.

Reply by email to bamurray at would be fine.  Thanks!

Ben Murray
Developmental and Cell Biology
University of California Irvine

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