Asn12andAsn278: Critical Residues for In Vitro BiologicalActivity of Reteplase

[摘要] Reteplase (rPA) is a thrombolytic agent used for the treatment of acute myocardial infarction. We studied the expression of rPA and its selected asparagine mutants after integration into thePichiagenome. Though methanol induction of the native and the rPA mutants showed similar expression levels (~200–250 mg/L), the mutants displayed significant loss of protease activity. Strikingly, the clot lysis activities of these mutants were considerably different. While mutation ofAsn12(N12P) of the Kringle 2 domain showed delayed clot lysis activity (t1/2=38 min) compared to the native rPA (t1/2=33 min), a faster rate of clot lysis (t1/2=27 min) was observed when theAsn278(N278S) of the serine protease domain was mutated. Interestingly, the slowest clot lysis activity (t1/2=49 min) demonstrated by the double mutant (N12P, N278S) suggests the dominant role ofAsn12in regulating the fibrinolytic activity of rPA. The results presented in this paper indicate that the fibrinolytic and the proteolytic activities of rPA are independent of each other.

[学科分类] 血液学