Table 5. Cap18 derivatives identified in the screening with lost antimicrobial activity or changed species-specificity.

Cap18 variant peptides				Antimicrobial Activity–MIC in μg/ml
Amino Acid	Position	Peptide Class	Mutation	L. lactis	S. Typhimurium	Y. ruckeri	A. salmonicida
L	6	II	L6D	16	8	≥32	16
		II	L6P*	8	4	≥32	8
		II	L6R	≥32	8	16	16
R	10	II	R10L*	≥32	4	8	4
I	13	I	I13D*	≥32	≥32	≥32	≥32
		I	I13F*	≥32	≥32	≥32	≥32
		II	I13H*	≥32	8	8	4
		II	I13N	≥32	8	-	8
		II	I13Q*	≥32	4	≥32	4
		II	I13S*	8	4	≥32	2
K	16	II	K16C*	≥32	8	2	4
		II	K16F*	≥32	8	4	4
		II	K16I*	≥32	4	4	4
		II	K16L*	≥32	4	4	4
		II	K16M*	≥32	4	4	4
		II	K16Y*	≥32	8	8	4
L	17	II	L17C	≥32	8	?	8
		I	L17D*	≥32	≥32	≥32	≥32
		II	L17H	≥32	8	≥32	8
		II	L17K*	≥32	4	≥32	4
		I	L17P*	≥32	≥32	≥32	≥32
K	18	II	K18P*	≥32	4	≥32	2
I	20	II	I20E*	≥32	4	16	8
		II	I20H*	≥32	2	8	2
		II	I20N*	≥32	4	16	4
		II	I20Q	≥32	8	8	8
		II	I20R	≥32	8	16	16
G	21	II	G21C*	≥32	8	4	4
		II	G21I	≥32	8	8	8
		II	G21L*	≥32	8	4	4
I	24	II	I24C*	≥32	4	4	4
		I	I24D*	≥32	≥32	≥32	≥32
		I	I24E	≥32	≥32	≥32	≥32
		II	I24G*	≥32	4	16	8
		II	I24H	≥32	8	≥32	8
		I	I24N*	≥32	≥32	≥32	≥32
		II	I24S*	≥32	4	16	8
L	27	II	L27P*	≥32	4	16	16
L	31	II	L31C	8	≥32	4	4
T	35	II	T35H	8	≥32	2	2
Y	37	II	Y37D	8	≥32	2	2

Class I peptides are highlighted in light grey and class II peptides are shown in dark grey. Cap18 variant peptides chosen for further analysis using pure peptides (purity >95%) are marked with *.