||Bacteria Escherichia coli
||Li GW, Burkhardt D, Gross C, Weissman JS. Quantifying absolute protein synthesis rates reveals principles underlying allocation of cellular resources. Cell. 2014 Apr 24 157(3):624-35. doi: 10.1016/j.cell.2014.02.033. p.631 right column bottom paragraphPubMed ID24766808
compared the rate of Met consumption with the maximum velocity
(Vmax) for its biosynthetic pathway. For each reaction in the
pathway, [they] calculated Vmax by multiplying the enzyme abundance
[they] determined by its published turnover number (kcat)
(Schomburg et al., 2002)."
||"The Vmax varies by more than one order
of magnitude among the reactions in Met biosynthesis, suggesting
that most reactions do not operate at saturating substrate
concentration. The last step that is catalyzed by MetE
has among the smallest Vmax (Figure 7A), suggesting that it
may be a bottleneck in this pathway. Remarkably, [researchers] found
that the maximal Met production rate allowed by MetE (Vmax,
34,000/sec per cell) matches the Met consumption rate (31,000 Met/sec BNID 110446)." MetE="Methionine Synthase (MetE)"