Table 1.

In vitro attributes of ribonucleases and their conjugates

Ribonuclease	Tma (°C)	kcat/KMb (106 M−1s−1)	Kd′c (nM)	IC50d (μM)	IC50e (μM)	Z
RNase A	64	6.4 ± 0.3	4.4 × 10−5 f	>25	>25	+4
G88R RNase A	63	8.2 ± 0.2	1.8 ± 0.3	3.3 ± 0.1	3.4	+5
G88C RNase A–NEM	64	6.8 ± 0.1	1.4 ± 0.4	28 ± 2	28	+4
(G88C RNase A)2–1	ND	12 ± 1	8.2 ± 0.2	22 ± 3	44	+8
(G88C RNase A)2–2	ND	11 ± 1	2.6 ± 0.2	25 ± 1	50	+8
(G88C RNase A)2–3	64	6.6 ± 0.6	9.6 ± 0.4	11 ± 1	21	+8
(G88C RNase A)2–4	ND	7.4 ± 0.5	18 ± 2	10 ± 1	20	+8
(G88C RNase A)2–5	ND	8.6 ± 0.1	8.6 ± 1.6	14 ± 1	27	+8
(G88C RNase A)2–6	ND	5.5 ± 0.03	14 ± 3	27 ± 2	55	+8
(G88C RNase A)3–7	ND	12 ± 1	39 ± 3	16 ± 1	48	+12
(G88C RNase A)3–8	64	16 ± 0.4	17 ± 1	8.6 ± 0.5	27	+13
(A19C RNase A)3–8	ND	7.5 ± 0.4	<1.4	>25	>25	+13
(D38R/R39D/N67R/G88C RNase A)3–8	ND	8.4 ± 0.3	ND	1.0 ± 0.1	3.3	+16
(C31A/C32A/G88C BS-RNase)3–8	ND	5.8 ± 0.3	84 ± 12	0.78 ± 0.05	2.1	+28
RNase 1	58	29 ± 1	2.9 × 10−7 g	>25	>25	+6
(G89C RNase 1)3–8	ND	16 ± 3	<1.4	1.5 ± 0.1	4.6	+19
ONC	90 h	0.0018 ± 0.00005	>150 i	0.22 ± 0.01	0.22	+5
(S72C ONC)3–8	ND	0.012 ± 0.0005	ND	0.79 ± 0.05	2.8	+16

ND, not determined.

^aValues T_m (± 2 °C) in 1×DPBS and determined by UV spectroscopy.

^bPer active-site values of k_cat/K_M (± SE) for catalysis of 6-FAM–dArU(dA)₂–6-TAMRA cleavage in 1×DPBS containing BSA (0.1 mg/mL) at (20 ± 2) °C. 6-FAM–dArUdGdA–6-TAMRA was the substrate for ONC and (S72C ONC)₃–8.

^cPer active-site values of K_d′ (± SE) for the complex with RI at (20 ± 2) °C.

^dPer molecule values of IC₅₀ (± SE) for incorporation of [methyl-³H]thymidine into the DNA of K-562 cells exposed to a ribonuclease and calculated with eq 3.

^ePer active-site values of IC₅₀ calculated by multiplying the IC₅₀ value by the number of monomers in the conjugate.

^fFrom ref (64).

^gFrom ref (45).

^hFrom ref (37) and determined by circular dichroism spectroscopy.

ⁱValue of K_i from ref (12).