Poly-L-Lysine(15-30wt)

viscous in solution, but the higher molecular weight poly-lysine (>300,000) provides more attachment sites per molecule.  The molecular weight poly-L-lysine often preferred by users is the 70,000-150,000. 

The lower molecular weight poly-L-lysine (30,000-70,000) is easier to use because it is less

Polymers of b oth D- and L-lysine are used to coat slides.  However, certain cells can digest poly-L-lysine; in this situation, poly-D-lysine should be used as the attachment factor so that the cells are not disrupted by excessive uptake of L-lysine.  

Poly-L-lysine is a nonspecific attachment factor for cells useful in promoting cell adhesion to solid substrates.  Poly-L-lysine enhances electrostatic interaction between negatively charged ions of the cell membrane and the culture surface.  When adsorbed to the culture surface, poly-L-lysine increases the number of positively charged sites available for cell binding.  

Procedure 

In order to determine the molecular weight by SEC-LALLS, it is necessary to succinylate the poly-L-lysine.  If this is not done, the product will form aggregates.

A method  for molecular weight determination by viscosity has been published.

Purification of high or low molecular weight  poly-L-lysines by size exclusion chromatography is not very effective.  Some success has been achieved using succinylated derivatives.  A more traditional method for fractionating polymers, such as dialysis with membranes of suitable molecular weight cut-off, is suggested.  

 None of the poly-L-lysine products are exposed to trifluoroacetic acid (TFA).  They are dialyzed to remove monomer, dimer, trimer, (i.e. short chains) and then analyzed by thin layer chromatography (TLC) to determine the effectiveness of this process. 

Poly-L-lysine is a positively charged amino acid polymer.   There is approximately one HBr per lysine residue.  The HBr allows the poly-L-lysine to be a crystalline solid and soluble in water.  To remove the HBr, solubilize it in a neutral buffer and dialyze  to remove the salts.  

Poly-lysine with mol. wt. >70,000 is useful in promoting cell adhesion to solid substrates..