Table 1.

Sequence and biological activities of the native and chemically modified Noxa BH3 peptides.

Name	Sequencea	Charge	FP assayb Ki (nM)	Cell viabilityc (%)
Noxa	AAQLRRIGDKVNLRQKLLN	+4	648±128	97.6±0.9
1	AAC′LRRIGDC′VNLRQKLLNd	+3	10±1	98.6±4.0
2	AAc′LRRIGDC′VNLRQKLLNe	+3	54±14	100.3±0.2
3	AAc′LRAIGDC′VNLRQKLLN	+2	23±8	85.9±2.2
4	AAc′LRAIGDC′VNLAQKLLN	+1	28±11	72.9±3.2
5	AAc′LRAIGDC′VNLAQALLN	0	29±4	44.3±0.2
6	AmAc′LRRIGDC′VNLRQKLLNf	+3	32±3	87.3±2.8
7	AmAmc′LRRIGDC′VNLRQKLLN	+3	22±4	80.5±4.7
8	AmAmc′LRAIGDC′VNLAQALLNg	0	22±8	34.8±0.5

^aPeptides with N-terminal Ala were acetylated while those with N-terminal N-methyl-Ala (A_m) were capped with methoxycarbonyl (Moc); all peptides were amidated at the C-termini.

^bCompetitive fluorescence polarization (FP) assay was performed three times to derive average IC₅₀ values along with standard deviations.

^cCell viability was measured with ATP assay by treating Mcl-1-overexpressing U937 cells (cultured in RPMI1640 supplemented with 5% FBS) with 20 μM peptides for 48 hours.

^dC′ denotes Bph-linked L-cysteine.

^ec′ denotes Bph-linked D-cysteine.

^fA_m = N-methyl-alanine

^gThe structure of 8 is shown as follows: