Table 2. Substitutions for Tyr-49 that were found to inhibit Kex2, furin, and PC7.

Enzyme	Substitution*
Kex2	Val, Asp, Glu, Cys
Furin	Gly, Ser, Asp, Glu, Cys, Cys+†
PC7	Ala, Val, Met, Trp, Cys+

^*Within the context of R₄R₁-eglin

^†Cys+ contained, in addition to Cys substitution at 49, a spontaneous substitution at Leu for Pro at position 38