We are currently using highly purified human thrombin
4,000 Units/mg [sigma #T-3010] for cleaving our fused protein
from glutathione S transferase. the price is becoming
prohibitive ~$300/1000 units. is there a better source for
thrombin, and not neccessarily human that will work as well.
our end product id being crystallized for structure determination
as well as for nmr characterization.