[Purification of hirudin by the method of isoelectric focusing]

Crude hirudin preparation was purified by isoelectric focussing in pH gradient 3-5. The presence of at least two active isoforms with pI 3.8 and 3.9 was demonstrated. The component with pI value of 3.9 possessed the specific activity as high as 8200 NIH AT units/mg.