Re: trypsin/ogen catalytic triad

peter Murray-rust (p.murray-rust@mail.cryst.bbk.ac.uk)
Mon, 8 May 1995 14:46:32 +0100 (BST)

Gail,
Very good questions - I hope someone answers more fully. The
role of the ASP is important - the original idea was that the ASP removed
a proton from the HIS which then had to remove a proton from the SER.
This was the so-called 'charge-relay' system. More recently, opnion is
that the proton does not actually transfer but that there is a polarisation.
It's easy to get into long debates over this - if so, makes sure that you
are discussing things which in principle are amenable to experiment.

Numbering of residues is a nightmare! Peopel like to keep the
same numebring between species so that they can always refer to, say, SER
195. This leads to lots of things like 16A, etc for insertions. But
'16a' might be used by some authors for disordered residues - there is no
definitive convention. Also, some proteins are postprocessed - does '1'
refer to the chain before or after processing?

P.

Peter Murray-Rust, Glaxo Research & Dev. (pmr1716@ggr.co.uk); (BioMOO: PeterMR)
Birkbeck College, ubcg09q@cryst.bbk.ac.uk, CBMT/Daresbury mbglx@seqnet.dl.ac.uk
http://www.cryst.bbk.ac.uk/PPS/index.html, http://www.dl.ac.uk/CBMT/HOME.html