Maximizing incorporation

Atom Economy Synthetic methods should be designed to maximize incorporation of all materials used in the process into the final product. 

It has been found that injected 35S-sulphate reaches maximal incorporation into rat brain cerebroside sulphate only 2 days after injection, and its activity remains practically constant and undergoes only very slow turnover. After 32 days the level of cerebroside sulphate activity was still 3/4 of that found on the second day after injection980. In liver, spleen and heart the maximum incorporation of 35S into cerebroside sulphate was reached after 12 hours and after 4 days the radioactivity virtually disappeared in these organs. 

The transformation of D-glucose by a Candida species has been followed catabolically and anabolically. Maximal incorporation into D-glucan and D-mannan is only achieved at a critical concentration of D-glucose. Dolichyl monophosphate-D-mannose is not an intermediate in the synthesis of the outer chains of the D-mannan-protein of Saccharomyces cerevisiae and dolichyl diphosphate oligosaccharides are synthesized by different D-mannosyl-transf erases. ... 

Now let us consider the case of essential metal Ions that, nevertheless, produce deleterious effects in the wrong concentration. Magnesium Ions are required for protein synthesis, yet Mg " " Ions in too high concentration lead to errors, as is illustrated by the studies of Szer and Ochoa (16) on the incorporation of phenylalanine and leucine in a ribosomal preparation using poly(U) as the messenger RNA. UUC as well as the UUU codon in poly(U) code for phenylalanine, so that incorporation of the latter represents correct translation. UUA and UUG code for leucine, so that leucine incorporation in this system is "incorrect." At low Mg2+ concentration only phenylalanine is in fact incorporated. Phenylalanine incorporation is maximal at lOmM Mg " " as the Mg " " concentration is increased, however, leucine also becomes incorporated and its maximal incorporation is at 20mM Mg2+ ( ). 

Incubation of SMP with NAD" labeled at the adenine moiety leads to a time-dependent incorporation of radioactivity into acid-precipitable material [13]. Maximal incorporation is achieved within about 60 min. With NAD labeled at the NMN-ribose moiety (kindly provided by K. Ueda) the efficiency of incorporation is doubled and amounts to about 220 pmol mg" protein (B. Frei, C. Richter 1984, unpubl.). With NAD labeled at the nicotinamide moiety incorporation is not observed. 

MV A would appear to be a better precursor than adenine and its derivatives for studies of cytokinin biosynthesis because of its reduced conversion into undesirable basic compounds [15], and the fact that its incorporation into isopentenyl groups of tRNA cytokinins has been established [15]. However, there are only a few reports of MVA s incorporation into free cytokinins [2, 5], and unfortunately the incorporation was extremely low, preventing proper characterization of the labelled cytokinins. Furthermore, MVA incorporation into cytokinins by V. rosea crown gall tissues could not be detected under conditions which result in maximal incorporation of [ C]-adenine into cytokinins [19]. The uptake of MVA (a mixture of optical isomers) by cell cultures is often very poor. Furthermore the radioactivity taken up is possibly swamped by a large endogenous pool of MVA. This severely limits the chance of detecting MVA s incorporation into cytokinins. 

The Composition of Typical Incubation Media for Obtainino Maximal Incorporation of Amino Aaos in Different Microsomal Systems... 

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