TABLE 1.

Entry	His6-Substrate	Antibiotic Activity	Synthetase Activitya (Relative to WT)
1	wt	+	++
2	E-13A	+	++
3	E-8P	+b	-
4	E-8A	ND	++
5	L-7E	+b	-
6	L-7K	-	-
7	L-7A	ND	+
8	D-6G	+	++
9	D-6P	ND	-
10	L-5P	ND	+
11	L-5Q	+	++
12	I-4G	+	ND
13	I-4P	ND	-
14	G-2V	+	++
15	G-2K	+	++
16	G-2E	+	ND
17	A-1I	+	ND
18	A-1K	+	++
19	A-1D	+	ND
20	A-1G	ND	++

^aAll mutants shown in entries 1-20 underwent four dehydrations when incubated for 12 h except for L-7K. The designations +, ++, and - refer to the following phenotypes of the mutant substrates when monitoring the time-dependence of dehydration by LctM. Mutants that were fully processed to a four-fold dehydrated product in a similar timespan as wt-LctA are indicated with ++. Mutants that were processed by LctM into a mixture of three- and fourfold dehydrated peptides in this time span are indicated with +. These mutants can be converted to fourfold dehydrated products upon longer incubation times. Mutants that were processed to predominantly three-fold dehydrated products without ever going to complete fourfold dehydrated products are indicated with -. ND, biological activity not determined (column 3) or not investigated in a time-dependent fashion (column 4).

^bBioactivity was only observed when at least some fourfold dehydrated product was produced.