Table 1.

Product summary of CylL_S, CylL_S–T2A and CylL_S–T1S/T2A peptides that were cyclized under different conditions.^a

Substrate	Modification enzymes		A ringb		B ring
	Dehydration	Cyclization	thioether	stereochemistry	thioether	stereochemistry
CylLS	CylM	CylM	MeLan	LL	Lan	DL
	HalM2	HalM2	MeLan	LL	Lan	DL
	CylM dehydratase domain	Non- enzymatically	MeLan	LL	Lan	DL (~ 80%)c LL (~ 20%)
	CylM dehydratase domain	CylM cyclase domain (in trans)	MeLan	LL	Lan	DL
CylLS- T2A	CylM	CylM	MeLan	LL	Lan	DL
	HalM2	HalM2	Not formed	N/Ad	Lan	NDe
	CylM dehydratase domain	Non- enzymatically	Not formed	N/A	Lan	ND
CylLS- T1A/T2A	HalM2	HalM2	Lan	LL (major) DL (minor)	Lan	DL
	CylM dehydratase domain	Non- enzymatically	Lan	DL (major) LL (minor)	Lan	DL

^aRing topologies of the final products were deduced form MS/MS fragmentation patterns, whereas configurations of (Me)Lan rings were assigned using GC-MS.

^bUnder all tested conditions, CylL_S and its variants cyclized with the same ring topology as that found in the natural cytolysin S.

^cRatio of products was estimated based on integration of the LC trace.

^dN/A: not applicable.

^eND: not determined.