Table 4. Effect of combining substitutions at positions 33 and 49 in R₄R₁-eglin.

Substitutions*	Kex2	Furin	PC7
Asp-33-Tyr-49	9.1 × 10-10†	2.5 × 10-9	1.3 × 10-9
Asp-33-Asp-49	5.6 × 10-11	3.3 × 10-10	1.8 × 10-9
Val-33-Asp-49	4.2 × 10-11	2.7 × 10-10	1.1 × 10-8

All values were determined by using purified inhibitors as described in Materials and Methods. Experimental errors were ±20%

^*In the context of R₄R₁-eglin

^†Inhibition constants (K_i, M) determined by purified variants for Kex2, furin, and PC7