. 2021 Sep 20;49:116415. doi: 10.1016/j.bmc.2021.116415

Table 4.

Lin et al. (2017) modifications and the resulting inhibition constants of various cyclic peptides. # Peptide bond, *Disulphide bond, Bz: Benzoyl capping.

Cyclic peptides	(12–18) Binding loop residues (aprotinin)							Glycine Linker		(35–39) Aprotinin’s second loop residues					K_i (µM)
Cyclic peptides	P3	P2	P1	P1′	P2′	P3′	P4′	Glycine Linker		35	36	37	38	39	K_i (µM)
Length optimization
1.	Pro	Cys*	Lys	Ala	Arg	Ile	Ile	Gly	Gly	Tyr	Gly	Gly	Cys*	Arg	232.3 ± 69.9
2.	Pro	Cys*	Lys	Ala	Arg	Ile	Ile	Gly	Gly	Tyr	Gly	Gly	Cys*	Ala	678.3 ± 244.1
3.	Pro	Cys*	Lys	Ala	Arg	Ile	–	Gly	–	Tyr	Gly	Gly	Cys*	Ala	376.8 ± 204.1
4.	Pro	Cys*	Arg	Ala	Arg	Ile				Tyr	Gly	Gly	Cys*	Ala	966.1 ± 328.8
5.	Pro	Cys*	Lys	Ala	Arg	Ile				Tyr	Gly	Gly	Cys*	Ala	14.5 ± 6.7
6.	*Pro*	Cys*	Arg	Ala	Arg	Ile^#				Tyr^#	Gly	Gly	Cys*	Ala	*2.9 ± 0.8*
7.	Pro	Cys*	Arg	Ala	Arg	Ile				Tyr	–	Gly	Cys*	Ala	467.9 ± 68.7
8.	Pro	Cys*	Arg	Ala	Arg	Ile				–	Gly	Gly	Cys*	Ala	780.3 ± 195.5
9.	Pro	Cys*	Arg	Ala	Arg	Ile				–	Gly	Gly	Cys*	Arg	29.7 ± 5.8
10.	–	Cys*	Arg	Ala	Arg	Ile				Tyr	Gly	Gly	Cys*	Arg	145.1 ± 27.9
11.	Pro	Cys*	Arg	Ala	Arg	Ile				–	–	Gly	Cys*	Ala	101.2 ± 24.8
Sequence optimization
	*Pro*	Cys*	Arg	Ala	Arg	Ile^#				Tyr^#	Gly	Gly	Cys*	Ala	*2.9 ± 0.8*
12.	Bz	Cys*	Arg	Ala	Arg	Ile				Tyr	Gly	Gly	Cys*	Ala	33.2 ± 6.5
13.	Pro	Cys*	Arg	Ala	Gln	Ile				Tyr	Gly	Gly	Cys*	Ala	No Binding
14.	Pro	Cys*	Arg	Ala	Trp	Ile				Tyr	Gly	Gly	Cys*	Arg	19.7 ± 8.8
15.	Pro	Cys*	Arg	Ala	Trp	Ile				Tyr	Gly	Gly	Cys*	Ala	144.8 ± 54.4
16.	Pro	Cys*	Arg	Ala	Arg	Ile				Asp	Gly	Gly	Cys*	Ala	69.3 ± 24.4
17.	Pro	Cys*	Arg	Val	Arg	Ile				Asp	Gly	Gly	Cys*	Ala	35.8 ± 16.4
18.	Pro	Cys*	Arg	Val	Arg	Ile				Tyr	Gly	Gly	Cys*	Ala	25.6 ± 9.9