Protein efficiency ration

The experimental evidences that medium engineering might represent an efficient method to modify or improve enzyme selectivity (alternative to protein engineering and to the time-consuming search for new catalysts) were immediately matched by the search for a sound rationale of this phenomenon. The different hypotheses formulated to try to rationalize the effects of the solvent on enzymatic enantioselectivity can be grouped into three different classes. The first hypothesis suggests that... 

Membrane-integrated proteins were always hard to express in cell-based systems in sufficient quantity for structural analysis. In cell-free systems, they can be produced on a milligrams per milliliter scale, which, combined with labeling with stable isotopes, is also very amenable forNMR spectroscopy [157-161]. Possible applications of in vitro expression systems also include incorporation of selenomethionine (Se-Met) into proteins for multiwavelength anomalous diffraction phasing of protein crystal structures [162], Se-Met-containing proteins are usually toxic for cellular systems [163]. Consequently, rational design of more efficient biocatalysts is facilitated by quick access to structural information about the enzyme. 

Semi-rational engineering of a coral fluorescent protein into an efficient highlighter. EMBO Rep. 6, 233-8. 

Some attempts have been made to rationally increase the efficiency of endosomal escape. One such avenue entails the incorporation of selected hydrophobic (viral) peptides into the gene delivery systems. Many viruses naturally enter animal cells via receptor-mediated endocytosis. These viruses have evolved efficient means of endosomal escape, usually relying upon membrane-disrupting peptides derived from the viral coat proteins. 

Major advances in the knowledge of biochemical pathways and the establishment of computer-based predictions of three-dimensional structures of proteins led to the development of new microbiological methods, such as rational protein design or directed evolution, giving scientists the possibility to provide tailor-made biocatalysts [15-19]. These methodological works on the disclosure of new efficient biocatalysts are not explicitly mentioned in this review unless they were applied in natural product synthesis. Biotransformations do not always compete with known chemical syntheses, but rather complement the portfolio of catalytic methods in organic chemistry. 

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