Table 1. Inhibitor Sequences and Inhibition Constants (K_i).

Inhibitor	Sequencea	Protease	Ki (nM)
MCoTI-II	GGVCPKILKKCRRDSDCPGACICRGNGYCGSGSD	KLK4	1.6 ± 0.1
		Plasmin	28 ± 631
		Trypsin	0.0023 ± 0.000718
		FXIIa	750 ± 8031
		Other proteasesb	>10,000
MC-K6R	GGVCPRILKKCRRDSDCPGACICRGNGYCGSGSD	KLK4	0.30 ± 0.1
MC-P5Q	GGVCQKILKKCRRDSDCPGACICRGNGYCGSGSD	KLK4	0.13 ± 0.08
MC-V3F	GGFCPKILKKCRRDSDCPGACICRGNGYCGSGSD	KLK4	1.3 ± 0.4
MC-FCQR	GGFCQRILKKCRRDSDCPGACICRGNGYCGSGSD	KLK4	0.10 ± 0.03
		Trypsin	31 ± 3
		FXa	500 ± 10
		Other proteasesc	>10,000
MC-FCQR-QK	GGFCQRILQQCQQDSDCPGACICKGNGYCGSGSD	KLK4	0.44 ± 0.15
		Trypsin	6.9 ± 0.7
		FXa	520 ± 10
		Other proteasesc	>10,000
MC-K6R-QK	GGVCPRILQQCQQDSDCPGACICKGNGYCGSGSD	KLK4	1.8 ± 0.5

^aAll peptides have a cyclic backbone with disulfide bonds between C4–C21, C11–C23, and C17–C28. Substituted residues are shown in bold, and Lys residues used for Alexa Fluor 488 labeling are underlined.

^bKLK5, KLK7, KLK14, FXa, thrombin, and plasma kallikrein.

^cKLK5, KLK7, KLK14, plasmin, FXIIa, thrombin, and plasma kallikrein.