Proline substitution effects

Table 12-1 Reductive Fe release from recombinant ferritins reconstituted to constant mineral size (480 Fe/molecule) the effect of proline substitution for the highly conserved leucine 134.

The effect of several amino acid replacements on toxin binding to eel electroplax membranes (Becker et al., 1992) differs from the corresponding effects on rat muscle sodium channels. Thus, proline substitution for Hyp did not affect activity in eel electroplax, and double replacement of Hyp and Hyp by Pro even increased activity by -27%. Asn replacements of Asp and Asp also slightly increased activity. These same substitutions decreased activities in rat muscle sodium channels, suggesting important structural differences between the active site on sodium channels in rat skeletal membrane and in the eel electroplax. 

Cytochrome c possesses three phyllogenetically-conserved proline residues that are presumably involved in the correct folding of the protein to form the native structure. The effects of substitutions at one of these sites, Pro-71 (Fig. 4), on the equilibrium and kinetics of yeast iso-2-cytochrome c unfolding have been studied by Nall and co-workers through comparison of the properties of a Thr... 

In summary, the chemistry of the donor/acceptor-substituted carbenoids represents a new avenue of research for metal-catalyzed decomposition of diazo compounds. The resulting carbenoids are more chemoselective than the conventional carbenoids, which allows reactions to be achieved that were previously inaccessible. The discovery of pan-tolactone as an effective chiral auxiliary, and rhodium prolinates as exceptional chiral catalysts for this class of rhodium-carbenoid intermediate, broadens the synthetic utility of this chemistry. The successful development of the asymmetric intermolecular C-H activation process underscores the potential of this class of carbenoids for organic synthesis. 

Masugi, J., Tamori, Y., Mori, H., Koike, T., and Kasuga, M. (2000). Inhibitory effect of a Proline- to-Alanine Substitution at Codon 12 of Peroxisome Proliferator Activated Receptor y2 on Thiazolidinedione-Induced Adipogenesis. Biochem. Biophys. Res. Commun. 268, 178—182. 

---