What's the largest prot. structure known?

[Gerard Kleijwegt]

In article <zjons-180894211142 at 130.60.120.10>, zjons at vetbio.unizh.ch (Zophonias O. Jonsson) writes:
|> Dear Xtallographers
|> 
|>   I am a layman who just loves to see those beautiful structures they show
|> in full color in Nature and Science.  Last year I was fortunate enough to
|> get to attend some lectures of men with names in the protein structure
|> community.  If I remember correctly one of them (Alwin Jones I think) said
|> that the lagrest structure determined to a reasonable (>3a) resolution was
|> somewhre close to 60 KDa.  Now I have three questions for you:
|> 
|> 1) Does my memory serve me right?  (Given the fact that those guys would
|> not have said anything that wasn't true)

i'm sure it does

|> 2) What is the current record (the largest single peptide that has had its
|> diffraction pattern traced)?

the largest i could find in a five-minute quick-n-dirty search
is 842 amino acids, of which 833 could be traced (~6800 non-H atoms;
assuming 14 grams/mole of atoms (to account for hydrogens & S) -> ~95 kDa)
this is glycogen phosphorylase (PDB id 3GPB), solved at 2.3 A

some multi-protein complexes are bigger than this (e.g. rubisco
L8H8, photosynthetic reaction centre) but they don't consist
of a single polypeptide

(and of course virus coats are larger, but they don't consist of
a single polypeptide chain but rather, for instance, of 60 copies
each of three smaller chains of ~130 residues, i.e. total of
60 * 3 * 130 residues)

|> 3) What is the current record for NMR? 

depends; two serine proteases of ~260 a.a. have been assigned
(one in Utrecht and one in Nijmegen; both published in J Biomol NMR
in January, i think), but their 3D structures have not been
published yet (as far as i know)

as for 3D nmr structures, i think the record (for the time being)
is of the order of ~150-170 residues

of course, when they deposit their coordinates at the PDB, nmr
spectroscopists make up for this by dumping twenty slightly
different copies of their structure ;-)

|> 
|>   I am sure there is someone in x-ray land who knows this, or at least has
|> the resources to extract this information from Brookhaven, PIR or wherever.
|> 
|> Sincerely
|> 
|> Zophonias

--gerard