TABLE 3.

Inhibition by l-methionine and S-adenosyl-l-methionine of enzyme activities in the extract of T. thermophilus HB8 grown in synthetic medium^a

Inhibitor and concentration (mM)	OAS SHaseb		OAH SHase		CTT β-lyase		CTT γ-lyase
	Sp act (μmol/min/mg of protein) (± SD)	Ratioc	Sp act (μmol/min/mg of protein) (± SD)	Ratioc	Sp act (nmol/min/mg of protein) (± SD)	Ratioc	Sp act (nmol/min/mg of protein) (± SD)	Ratioc
None	1.20 (± 0.25)	1	0.046 (± 0.009)	1	10.2 (± 2.00)	1	1.46 (± 0.32)	1
l-methionine
1	1.05 (± 0.14)	0.87	0.042 (± 0.004)	0.91	10.3 (± 2.12)	1.01	1.40 (± 0.36)	0.96
5	0.68 (± 0.09)	0.57	0.037 (± 0.007)	0.79	10.3 (± 2.81)	1.01	0.72 (± 0.12)	0.49
10	0.43 (± 0.07)	0.36	0.030 (± 0.005)	0.65	11.6 (± 2.52)	1.15	0.58 (± 0.12)	0.39
S-adenosyl-l-methionine
0.1					10.0 (± 2.26)	0.98	1.46 (± 0.44)	1.0
1					10.1 (± 2.11)	0.99	0.98 (± 0.24)	0.67
5	0.97 (± 0.47)	1.22	0.045 (± 0.009)	0.95

^aThe extract was obtained from cells cultured in 1 liter of synthetic medium as described in Table 1. Average values of three determinations for all enzyme activities are shown. 

^bSHase, sulfhydrylase. 

^cAmounts are relative to the results without inhibitors.