Nucleosides. Part VIII. Glucosides of uracil and thymine and the O→N-glycosyl rearrangement

Abstract

By varying the conditions of reaction between the silver salt of uracil and 2,3,4,6-tetra-O-acetylglucopyranosyl bromide (ABG) and from a study of the rearrangement of uracil 0 ( 2 ) 0 ( 6 ) -and N(3)0(6)-bisglucosides it has been shown that these compounds are intermediates in the formation of the uracil N-glucosides, and that a competitive route must exist for the formation of uracil N(3)-glucoside. In the case of thymine, the formation of the N(3)-glucoside from the 0(2)0(6)-bisglucoside via the N(3)0(6)-bisglucoside is confirmed.

Maize (Zea mays)‐derived bovine trypsin: characterization of the first large‐scale, commercial protein product from transgenic plants

“…The trypsinogen gene from Bos taurus (GenBank ® TRBOTR) was fused to the nucleic acid coding sequence for the maizeoptimized barley α-amylase signal sequence [15] at the 5 end of the trypsinogen gene to target the protein to the cell wall. The construct was subcloned downstream of a 1.4-kb fragment of the maize globulin 1 promoter and upstream of a 315-bp fragment of the potato protease inhibitor II (PINII) terminator.…”

Nucleotide sequence of the maltotetraohydrolase gene from Pseudomonas saccharophila

“…The amino acid sequences of various amylolytic enzymes such as u-amylase [4][5][6][7][8],/~-amylase [9], glucoamylase [10], cyclomaltodextrin glucanotransferase [11][12][13], maltohexaohydrolase [14], isoamylase [15], and pullulanase [16], have been determined by direct protein analysis or deduced from the DNA sequences. It is of great interest to study the molecular basis for the difference between the specificity of the G4-forming amylase and those of the other amylolytic enzymes.…”

Reactions of Transglycosylation in the Nucleoside Chemistry

“…The substrate (32) undergoes a nucleophilic attack of azide ion at the C3'-position, and this leads to the expected main product, 5'-tritylated AZT. However, in a side-reaction, the azide ion can attack C1' as well, and this results in the formation of -azido intermediate (33), which may undergo recyclization to either (32) or (34). The cyclonucleoside (34) may further react with azide anion to produce a 3-isomer of AZT.…”

“…A similar 1 3 transglycosylation takes place in the reaction of (32) with O,O-diethyl phosphate or O,O-diethyl phosphorothioate anions [52]. Furthermore, because the pyrimidine moiety is negatively charged in the structure (33), and a leaving group is present in the C1'--position, the conversion (33) (34) may be considered as an intramolecular version of the anionic glycosylation [53].…”

“…For example, condensation of silver salts of thymine or uracil and 1-bromo-2,3,4,6-tetra-O-acetyl--D-glucopyranose gives complicated mixtures of products, including all possible O-and N-substituted ones [33]. It has been shown that only N-glycosylated products are stable.…”