ABSTRACT
The recombinant thrombin was essentially identical to human a-thrombin purified from human plasma by several different assay systems. It was noted that 25% of the recombinant prethrombin was two amino acids shorter at the amino terminal than wild-type prethrombin-2; however, both forms of recombinant prethrombin-2 yielded the same species of a-thrombin. Arcone and coworkers10 prepared several thrombin mutants where active-site residues and an exosite residue were modified. The expression system used for prethrombin-2 used a dihydrofolate reductase–deficient CHO cell line. The mutation in desETW thrombin is a deletion and may result in more of an effect on conformation than would be observed in a substitution mutant such as E202M. One common complaint of chemical modification studies was that there was conformational change secondary to the modification responsible for the observed changes in function. Additional work from this group provided more support for the importance of binding sodium ions in the activity of thrombin.
