Branched RNAs synthesis

Figure 5.5 Individual deoxyribozymes for branched RNA synthesis. (A) 7S11 deoxy-ribozyme. Note the four Watson-Crick paired regions denoted P1-P4. (B) 10DM24 deoxyribozyme. (C) 6CE8 deoxyribozyme. (D) 6BX22 deoxyribozyme.

Further efforts needed to develop deoxyribozymes for branched RNA synthesis... 

As RNA synthesis has become routine, the synthesis of more complex oligomers has been investigated. One particular area of interest in RNA synthesis is the formation of cyclic and lariat RNA. The use of a protected universal building block containing the selectively activated 2 -H-phosphonate and 3 -chlorophenylphosphate has been used to prepare branched oligoribonucleotides and lariat structures."" The synthesis of small to medium cyclic RNA can be carried out, providing that the linear precursor attached to the support has a... 

Damha, M. J, Pon, R. T, and Ogilvie.K. K (1985) Chemical synthesis of branched RNA novel trinucleoside diphosphates containing vicinal 2 -5 and 3 -5 phosphodiester linkages. Tetrahedron Lett 26,4839-4842... 

In the case of hyperphenylalaninaemia, which occurs ia phenylketonuria because of a congenital absence of phenylalanine hydroxylase, the observed phenylalanine inhibition of proteia synthesis may result from competition between T.-phenylalanine and L-methionine for methionyl-/RNA. Patients sufferiag from maple symp urine disease, an inborn lack of branched chain oxo acid decarboxylase, are mentally retarded unless the condition is treated early enough. It is possible that the high level of branched-chain amino acids inhibits uptake of L-tryptophan and L-tyrosiae iato the brain. Brain iajury of mice within ten days after thek bkth was reported as a result of hypodermic kijections of monosodium glutamate (MSG) (0.5—4 g/kg). However, the FDA concluded that MSG is a safe kigredient, because mice are bom with underdeveloped brains regardless of MSG kijections (106). 

The minimal cell, as the simplest system which has all the required properties of life (metabolism, self-reproduction and the ability to evolve), is presently studied as part of a new research discipline synthetic biology. This includes subjects such as synthesis in branches of biological systems, for example, of new RNA species, new peptides and new nucleic acid analogues, as well as the synthesis of peptide nucleic acids. One example is the work of M. R. Ghadiri and G. von Kiedrowski on self-replication of oligonucleotides and oligopeptides (Luisi, 2006b). 

Linn, D., and W. Maas, Reverse transcriptase-dependent synthesis of a covalently linked branched DNA-RNA compound in E. coli B. Cell 56 891-904, 1989. 

Figure 5 A Synthesis of 2,5,-branched and lariat RNA by reaction of a 2 -OH group with a S -triphosphatc. The product is a lariat when the dashed loop is present con-necting the two substrates.

Damha, M. J., Ganeshan, K., Hudson, R. H., and Zabarylo, S. V. (1992). Sobd-phase synthesis of branched oligoribonucleotides related to messenger RNA spbcing intermediates. Nucleic Adds Res. 20, 6565-6573. 

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