Potassium Chloride → HCID 10557857, compound

Participants

Reaction Steps

A mixture of Polymyxin B (20 g), immobilised papain (185 ELU/g), potassium phosphate buffer (25 mM; pH 7, 1.25 L), potassium chloride (30 mM), EDTA (10 mM) and cysteine (1 mM) was incubated at 37° C. for 18 h with gentle agitation. The progress of the reaction was monitored by LC-MS using the conditions outlined in Table 1. The immobilized papain was removed by filtration and the filtrate was concentrated in vacuo to leave a solid residue which was re-suspended in 10% aqueous methanol and left at room temperature overnight. The supernatant was decanted and concentrated in vacuo. Polymyxin B nonapeptide was purified from the residue by SPE on C18 silica, eluting with 0-10% aqueous methanol. Evaporation of the appropriate fractions gave the product as a white solid. m/z 482, [M+2H]2+

Provenance & Evidence