TABLE 1.

Kinetic parameters of ribosomal peptidyltransferase during incubation of the E. coli isolate in sea salts medium, as evaluated by the puromycin reaction^a

Ribosome source	kmax (min−1)	Ks (mM)	kmax/Ks (min−1/mM)
Supplemented M9 medium (mid-log-phase cells)	1.54 ± 0.04	0.670 ± 0.009	2.30 ± 0.13
Sea salts medium (24 h)	1.00 ± 0.05	0.870 ± 0.012	1.15 ± 0.12
Sea salts medium (72 h)	1.05 ± 0.04	1.333 ± 0.018	0.79 ± 0.06
Sea salts medium (168 h)	1.05 ± 0.04	2.000 ± 0.025	0.53 ± 0.04
Sea salts medium (24 h) (ribosomes − L7/L12b)	1.02 ± 0.05	2.430 ± 0.020	0.42 ± 0.04
Reconstituted ribosomesc	1.21 ± 0.03	0.690 ± 0.008	1.75 ± 0.09

^aAll data used in the kinetic analysis were obtained with ribosomes isolated from four independently starved cultures. 

^bRibosomes isolated from 24-h-starved cells and artificially depleted of L7/L12 protein. 

^cRibosomes isolated from 24-h-starved cells, artificially depleted of L7/L12 protein and then reconstituted with L7/L12 protein extracted from mid-logarithmic-phase cells.