Deoxyribosyl Transferases

In this section some examples are discussed in order to prepare nucleoside analogs by base interchange through a transglycosylation reaction. In these processes two different types of intramolecular enzymes are usually employed nucleoside phos-phorylases and N-2 -deoxyribosyl transferases. 

In summary, the nucleoside phosphorylases provide a regio- and stereo-specific route for nucleoside synthesis which is applicable to nucleoside analogs which are modified in either the base or the sugar moiety. These processes provide good yields of products in most cases without the extensive protection and deprotection steps involved in traditional chemical synthesis of nucleosides. Application of this strategy to the synthesis of 2 -deoxy- and 2, 3 -dideoxynucleosides was reported with the use of N-deoxyribosyl transferase from Lactobacillus species1301, 312). 

NaOH, nucleoside deoxyribosyl transferase (from Lactobacillus helveticus). SCHEME 12.51... 

During the process of purifying the two known nucleoside deoxyribosyl transferase activities from Lactobacillus leichmannii, a third isoenzyme was assayed, which... 

It was demonstrated that these three enzymes have not only deoxyribosyl transferase, but also deoxynucleoside kinase, ribonucleoside triphosphate reductase, adenosine deaminase and DNA polymerase activity. 

It is known that the microorganism Lactobacillus leichmannii has two nucleoside deoxyribosyl transferases, DRT I (which has no EC number yet) and DRT II (EC... 

The nucleoside deoxyribosyl transferase - activities were separated from each other on DEAE-Sephacel column, which was equilibrated with 20 mM of phosphate buffer, 100 mM NaCl, 0.1 mM EDTA, 1 mM mercaptoethanol. On the NaCl gradient, VI elutes between 160 and 190 mM, V2 between 260 and 280 mM, and V3 at the end of the breakthrough with 100 mM of NaCl (see Figure 1). 

Deoxy-2-thiouridine has been prepared using immobilized W-deoxyribosyl transferase from Lactobacillus leichmanii, whilst radical deoxygenation was used to prepare 2 -deoxy-3-isoadenosine (38), which was converted into the two regioisomeric dinucleoside monophosphates with thymidine. ... 

All tested enzymatic (microbial ribosylnucleotide transferase) methods for the transfer of the ribosyl and 2-deoxyribosyl moiety to the alkaloid molecule (agroclavine) failed (e.g.[ 35]), presumably due to the very narrow specificity of the particular enzymes for certain aglycone molecules. 

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