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. 2013 Jun 6;288(30):21802–21814. doi: 10.1074/jbc.M113.462804

TABLE 5.

Kinetic constants and SI for reactions of serpin B8, α1PDX, and α1PDX-serpin B8 chimeras with furin and furin-PC(298–300) loop chimeras

Values of ka and SI ±S.E. for serpin-furin reactions were measured at pH 7.5, 25 °C as in Table 1. SIs for the reactions of α1PDX-serpin B8 P6–P5′-YE chimera with the furin-PC loop chimeras could not be determined because of enzyme instability over the long times required for complete reaction.

Furin-PC chimeras Serpin B8
α1PDX
α1PDX-serpin B8 P6–P5′
α1PDX-YE
α1PDX-serpin B8 P6–P5′-YE
ka SI ka SI ka SI ka SI ka SI
m1 s1 m1 s1 m1 s1 m1 s1 m1 s1
Wild-type 2.3 ± 0.2 × 105 2.2 ± 0.1 1.1 ± 0.1 × 106 1.1 ± 0.1 1.1 ± 0.1 × 105 1.4 ± 0.1 2.1 ± 0.7 × 105 1.9 ± 0.1 1.5 ± 0.2 × 103 1.3 ± 0.2
F-PC1 9.8 ± 1.2 × 104 1.4 ± 0.1 2.6 ± 0.5 × 106 1.7 ± 0.2 7.1 ± 1.4 × 104 1.3 ± 0.1 9.3 ± 1.7 × 105 1.3 ± 0.1 5.6 ± 0.1 × 103 NDa
F-PC2 6.4 ± 1.4 × 104 1.6 ± 0.2 1.1 ± 0.2 × 106 1.5 ± 0.1 5.3 ± 0.5 × 104 0.9 ± 0.1 1.7 ± 0.2 × 105 1.2 ± 0.1 9.2 ± 0.7 × 102 ND
F-PC4 1.3 ± 0.1 × 105 1.6 ± 0.1 1.0 ± 0.2 × 106 1.4 ± 0.2 6.4 ± 0.9 × 104 1.6 ± 0.1 2.4 ± 0.5 × 105 1.3 ± 0.2 3.4 ± 0.2 × 103 ND
F-PC5/6 4.9 ± 0.6 × 104 1.1 ± 0.1 2.2 ± 0.4 × 106 1.5 ± 0.2 6.4 ± 1.5 × 104 0.9 ± 0.1 9.4 ± 1.6 × 105 1.2 ± 0.2 2.6 ± 0.3 × 104 ND
F-PACE4 9.4 ± 0.9 × 104 1.8 ± 0.1 1.6 ± 0.3 × 106 1.9 ± 0.3 1.3 ± 0.1 × 105 0.8 ± 0.2 2.4 ± 0.5 × 105 1.4 ± 0.3 1.0 ± 0.1 × 103 ND
F-PC7 2.5 ± 0.4 × 105 2.1 ± 0.1 1.0 ± 0.2 × 106 1.4 ± 0.1 6.0 ± 0.7 × 104 1.3 ± 0.1 2.4 ± 0.2 × 105 1.1 ± 0.0 3.0 ± 0.1 × 103 ND
298–300 AAA 6.1 ± 1.3 × 104 1.5 ± 0.3 1.8 ± 0.1 × 106 1.2 ± 0.1 1.9 ± 0.8 × 104 1.0 ± 0.1 1.3 ± 0.1 × 105 0.8 ± 0.2 1.5 ± 0.1 × 103 ND

a ND, not determined.