Patent ID: 8058235

Claim:
A method for preparing a composition comprising purified glatiramer acetate having a pyroglutamate concentration of 2000-7000 ppm and a Mp of 5000-9000 Da, the method comprising: polymerizing N-carboxy anhydrides of L-alanine, benzyl-protected L-glutamic acid, trifluoroacetic acid protected L-lysine and L-tyrosine to generate a sample comprising intermediate-1; treating the sample comprising intermediate-1 to partially depolymerize and deprotect benzyl-protected L-glutamic acid, thereby generating a sample comprising intermediate-2, wherein water is present for at least a portion of the treatment in a range of 4-25% weight/weight (w/w) against intermediate-1 present at the beginning of treatment; treating the sample comprising intermediate-2 to deprotect trifluoroacetic acid protected L-lysine, thereby generating intermediate-3; further processing the intermediate-3 to generate glatiramer acetate; and purifying the glatiramer acetate to generate purified glatiramer acetate having a pyroglutamate concentration of 2000-7000 ppm and a Mp of 5000-9000 Da.