Wanted Lectin A of Lens culinary

Flip Hoedemaeker sbtnfh at rulsfb.leidenuniv.nl
Mon Mar 20 05:08:28 EST 1995


XYZZYX at news.delphi.com (XYZZYX at DELPHI.COM) wrote:
>
> hi, it's george again.  Thought I'd follow up with a little more info.  I 
> had a Sigma catalog out today, so I checked their entry for Lens 
> culinaris lectin.  Unfortunately, the stuff they sell is a mixture of 
> A+B.  The lectin occurs naturally as a dimer of A+B, which probably 
> explains why that is all that most people seem to sell.  I tried to pull 
> down a sequence for each from the various databases but was unsuccessful; 
> only one sequence appears.  Both isolectins have the same approximate Mr 
> (49000) but (I think) differ in isoelectric points.

I'm not sure about lens lectin, but the very much related pea lectin
is a mixture of two isolectins that differ in charge and are derived
from one gene by differential processing of the C-terminus. This could
be the case for L.cu lectin as well, or, like in Lathyrus, two genes
could be present coding for highly related lectins which differ in
charge. Both pea and lathyrus isolectins have the same specificity.

  I'm not sure if they 
> are disulfide linked (run some on a gel +/- BME, that ought to show it).  

As far as I know, legume lectins do not contain cys residues and 
therefore disulphide bridges.
> Both isolectins have affinity for terminal 
> alpha-D-mannose and alpha-D-glucose so it probably won't work to run an 
> affinity column to separate them. Ion exchange chromatography or 
> Hydrophobic interaction chromatography might work (and HIC is a nice 
> follow on step to Ammonium sulfate pptn., as well), though I would still 
> recommend an initial separation on a sugar column (e.g. mannose-agarose) 
> to get a reasonably pure material first. 

Good point! First do a affinity chromatography step on plain Sephadex

after that, best separation is obtained with a chromatophocusing
column (Pharmacia)
 There was one reference listed 
> in the sigma catalog: Howard, I.K., et al.,J. Biol. Chem., 246, 1590 (1971).

Let me add my own humble contribution to Science:

Hoedemaeker et al Plant Mol Biol 24: pp 75-81 (1994)
> 
> Good luck.

also from me! Flip



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