Table 4.

Peptide aldehdye and boronic acid inhibitors of PSA.

	Compound	Ki(μM)
	Leucine aldehydes
25	Z-SSKLL-H	6.51 ± 0.25
26	Z-SSKFL-H	11.9 ± 0.9
27	Z-SSKYL-H	13.09 ± 0.91
28	Z-SSKML-H	13.7 ± 1.2
29	Z-SSKQL-H	21.79 ± 0.51
30	Z-SSKIL-H	37.43 ± 2.43
31	Z-SSKKL-H	57.85 ± 1.14
32	Z-SSKVL-H	70.71 ± 1.77
33	Z-SSKTL-H	>100
34	Z-SSKAL-H	>100
35	Z-SSKF(Br)L-H	>500
36	Z-SSKLD-H	>1000
37	Z-SKLL-H	42.43 ± 2.13
38	Z-SSKL-H	>1000
39	Z-KLL-H	>100
40	Z-YL-H	>500
41	Z-KL-H	>1000
42	Z-QL-H	>1000
43	Z-SSKLL-H	>1000
	Norleucine aldehdyes
44	Z-SSKLNle-H	11.24 ± 0.26
45	Z-KLNle-H	414.1 ± 22.49
46	Z-KNle-H	>1000
47	Z-QNle-H	>1000
48	Z-SSKNle-H	>1000
49	Z-SSKLNle-H	>1000
	Peptidyl boronic acids
50	Z-Q(boro)L	265.15 ± 18.39
51	Z-K(boro)L	353.5 ± 23.68
52	Z-SSK(boro)L	18.49 ± 1.48
53	Z-SSK(boro)Nle	34.21 ± 0.83
54	Z-KL(boro)L	5.98 ± 0.24
55	Z-KL(boro)NLe	23.57 ± 0.47
56	Z-SSKL(boro)Nle	0.398 ± 0.020
57	Z-SSKL(boro)L	0.065 ± 0.005
	D-isomer amino acids
58	Z-SSKL(boro)L	0.149 ± 0.009
59	Z-SSKL(boro)L	21.48 ± 2.28
60	Z-SSKL(boro)L	28.67 ± 1.32
61	Z-SSKL(boro)L	75.76 ± 5.21
62	Z-SSKL(boro)L	32.21 ± 1.73
63	Z-SSKL(boro)L	227.27 ± 11.61
64	Z-SSKL(boro)L	439.94 ± 19.04
	Lysine derivatives
65	Z-SSL(boro)L	3.86 ± 0.29
66	Z-SSK(Ac)L(boro)L	0.294 ± 0.026

Residues containing D-isomer amino acids are underlined.