Table 1.

Bovine MsrA activation by fusaricidin analogues having various amino acid substitutions in the basic scaffold structure (see Fig. 1). Enzyme specific activity is defined as nmol DABS Met formed/μg protein/30 minutes. The specific activity of the control bMsrA was 6.5±1.19. Because of solubility issues all of the analogues used in this Table were initially dissolved in dimethylformamide (DMF), resulting in final concentrations in the reactions of 0.25% DMF and 25 uM analogue. Using analogue 2, which is soluble in water it was shown that DMF had no effect on the reaction. Fold activity is defined as the increase in enzyme activity compared to the control activity (no activator). For clarity, using the control activity as 1, a fold activity value of 1.2 (e.g., analogue 5 in Table1) represents a 20% increase in activity, whereas a fold activity value of 6.2 (e.g., analogue 2 in Table 1) represents an enzyme activity 6.2 times the control.

Analogue	R2	R3	R4	R6	Fold Activity
2	D-Ile	L-Phe	D-Leu	D-Arg	6.2±0.11
3	D-Phe	L-Leu	D-Leu	D-Arg	5.2±0.51
4	D-Leu	L-Leu	D-Phe	D-Arg	3.8±0.30
5	D-Trp	L-Asp	D-Tyr	D-Tyr	1.2±0.19
6	D-Tyr	L-Asp	D-Phe	D-Tyr	1.2±0.08
7	D-Tyr	L-Asp	D-Leu	D-Tyr	1.6±0.28
8	D-Ile	L-Leu	D-Leu	D-Arg	3.8±0.65
9	D-Phe	L-Leu	D-Leu	D-Lys	4.2±0.43