Fig. 4.

Degradation of substrates with increasing sequence diversity. (A, Upper) Representative degradation reactions of 5′-C₂₆A₁₀-3′ (1 nM; Rrp6p, 110 nM) and 5′-A₂₆C₁₀-3′ (1 nM; Rrp6p, 110 nM). (A, Lower) kinetic parameters for the degradation of 5′-C₂₆A₁₀-3′ (solid circles) and 5′-A₂₆C₁₀-3′ (open circles) for individual nucleotides (Upper plot, degradation rate constant (k_f); Lower plot, apparent dissociation constant for productive binding (K_1/2^P). Data show results of the global data fits, and error bars mark the SEs of the global fits. Shading indicates the transition between A and C sequence blocks. (B, Upper) Representative degradation reactions of a 36-mer RNA (R₃₆,1 nM; Rrp6p, 110 nM) with mixed sequence (indicated on the right). (B, Lower) Kinetic parameters for the degradation of R₃₆, as in A. (C, Upper) Representative degradation reactions of a 41-mer RNA (R₄₁,1 nM; Rrp6p, 110 nM) with mixed sequence, including four 3′-A₄C-5′ repeats (sequence indicated on the right). (C, Lower) Kinetic parameters for the degradation of R₄₁, as in A. Shading indicates the 3′-A₄C-5′ repeats.