Convergence, evolutionary

Other environmental conditions, such as changes of the pH value of sea water, or in reactant concentration, could have led to decomposition reactions. Kuhn s initial model distinguishes between divergent and convergent evolutionary phases ... 

Chymotrypsin and subtilisin also differ in their amino acid sequences, number of disulfide bridges (chymotrypsin has five, whereas subtilisin has none), and overall three-dimensional structures. The striking difference in structure and common catalytic mechanism are taken as evidence of an independent but convergent evolutionary process. 

The amino acid sequences of OBPs show little homology between orders and no homology to analogous proteins found in vertebrate olfaction systems, implying convergent evolutionary processes. However, there is conservation of six cysteine residues in all insect OBPs,... 

That CN is found in the [NiFe]- and [FeFe]-H2ases and CO is found in all three H2ases, and that the three enzymes are phylogenetically distinct, speaks to convergent evolutionary processes that recruited these toxic ligands to facilitate the reversible reduction/oxidation process for hydrogen metabolism at iron. 

In a simplified version of ISM, each site is considered only once (Figure 2.4). This means that, in the given case of four sites, 65 libraries of mutants are possible, the overall evolutionary process being convergent. Of course, not all branches have to be explored. Indeed, this embodiment of ISM has been shown to be highly successful in the rapid evolution of enantioselectivity [23,26,27] and thermostability [28]. 

Zuckerkandl, E., and Pauling, L. (1965). Evolutionary divergence and convergence in proteins. In Evolving Genes and Proteins (V. Bryson and H. J. Vogel, eds.), pp. 97-166. Academic Press, New York. 

Fig. 4. Adjacent genes with conserved relative transcription orientation versus evolutionary distance. The plot shows the fraction of conserved gene pairs with the same relative direction of transcription between two species. Shown are pairs with a single direction of transcription, pairs with a divergent direction of transcription, and pairs with a convergent direction of transcription. The X axis represents the small subunit rRNA distance between the species (Fig. 3). The number of conserved adjacent pairs declines nonlinearly with phylogenetic distance and was therefore depicted on a logarithmic scale. Note that the vast majority of conserved adjacent pairs with a conserved relative transcription orientation are transcribed in the same direction. Divergently transcribed pairs are better conserved than convergently transcribed ones, hinting at the conservation of divergent promotors.

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