Table 2.

Thermodynamics of Tat-SF1 binding SF3b1 ULMs

Average values and standard deviations of three independent titrations.

Interaction	KD	ΔH	−TΔSa
	μm	kcal mol−1
Wildtype Tat-SF1titrated with ULM regions
SF3b1ULM	1.8 ± 0.9	−66.1 ± 3.0	58.0 ± 3.0
ULM1	3.0 ± 0.5	−11.8 ± 0.3	4.1 ± 0.3
ULM2b	No detectable binding
ULM3b	No detectable binding
ULM4c	18.9 ± 4.7	−34.1 ± 25.3	27.5 ± 25.5
ULM5	0.8 ± 0.1	−18.7 ± 1.0	10.2 ± 1.2
E286K/D290K mutant Tat-SF1 titrated with ULM5
ULM5b	No detectable binding
E286K/F337A mutant Tat-SF1 titrated with ULM5
ULM5b	No detectable binding

^a Calculated using −TΔS = ΔG-ΔH, with ΔG = −RT ln (K_D⁻¹) and T = 303 K.

^b No heats detected during titration of 200 μm ULM into 20 μm Tat-SF1 protein.

^c Values are estimates due to low binding affinity.