FIGURE 3.

BACE1 processing of APP substrates in a reconstituted in vitro enzyme assay. A and B, TR-FRET analysis of cleavage rates for A673T and A673V peptides in a WT context (A) or in combination with the Swedish (K670N/M671L) mutation (B). C, kinetic analysis of FRET cleavage data. A673T and A673V mutations decreased and increased the rate of catalytic cleavage (V_max) of the short APP substrate, respectively, without affecting the K_m value. D, competitive inhibition of the catalytically efficient Swedish peptide substrate by peptide substrates without Swedish mutation, having a slow cleavage rate. WT, A637T and A673V competitive peptides yielded comparable IC₅₀, suggesting similar binding affinity. Values represent mean ± S.D. of three independent experiments, each with technical replicates.