It has been found that Ser His could cleave bovine serum albumin(BSA), with the most suitable pH around 6.0. The kinds of buffers have different influences on the cleavage activity. The phosphate buffer and BR buffer ...It has been found that Ser His could cleave bovine serum albumin(BSA), with the most suitable pH around 6.0. The kinds of buffers have different influences on the cleavage activity. The phosphate buffer and BR buffer are the most effective. The hydroxyl group of the serine residue is the essential functional group for the cleavage, while the amide bond, imidazole, and carboxyl group of Ser His increase the cleavage activity.展开更多
Azido-3′-deoxythymidine(AZT) was the first clinically approved drug against HIV infection, despite its undesirable side reactions, such as bone marrow suppression. In our aim to develop new chemical entity of anti-tu...Azido-3′-deoxythymidine(AZT) was the first clinically approved drug against HIV infection, despite its undesirable side reactions, such as bone marrow suppression. In our aim to develop new chemical entity of anti-tumor and anti-HIV, the H-phosphonate 6 of AZT conjugate with diosgenin was synthesized by a tandem transesterification reaction for the first time. There are the merits of easy operation and high yield in the reported method. It could be extended to synthesize other diosgenin phosphonate conjugates such as carbohydrate and peptide.展开更多
The tyrosine \%O\%\|phosphorylation \%via\% Atherton\|Todd reaction, which was a classical reaction for phosphorylation amines, was first studied in this paper. Reaction of Boc\|Tyr\|OCH\-3, which was selected as mode...The tyrosine \%O\%\|phosphorylation \%via\% Atherton\|Todd reaction, which was a classical reaction for phosphorylation amines, was first studied in this paper. Reaction of Boc\|Tyr\|OCH\-3, which was selected as model substrate, with three dialkyl \%H\%\|phosphonate diester in the presence of CCl\-4 and triethylamine produced the corresponding tyrosine \%O\%\|phosphorylation products in a high yield(over 80%). The reaction was conducted in anhydrous THF solution and monitored by \{\}\+\{31\}P NMR and TLC. Then reaction of Boc\|Tyr\|OCH\-3 with a complicated H\|phosphonate diester, \%O\%\|3\|acetylthymidin\|5\|yl \%O\%\|isopropyl \%H\%\|phosphonate diester, also gave a good result and this would be an alternative approach for the synthesis of nucleotide \%O\%\|tyrosine (or tyrosine containing peptide) conjugate. Further, the successful \%O\%\|phosphoration of three tyrosine containing protected dipeptides, Boc\|Tyr\|Val\|OCH\-3, Boc\|Ala\|Tyr\|OCH\-3, Boc\|Tyr\|Tyr\|OCH\-3, with diisopropyl \%H\%\|phosphonate diester demonstrated the effectiveness of the method.展开更多
Phosphoramidates of nucleosides are continuing to be an important class of rationally designed therapeutics especially as oligonucleotide analogs employed as antisense and antigene agents. A series of different nucleo...Phosphoramidates of nucleosides are continuing to be an important class of rationally designed therapeutics especially as oligonucleotide analogs employed as antisense and antigene agents. A series of different nucleoside 5’-thiophosphoramidates have recently been synthesized, their electrospray ionization mass specra have been investigated. The positive and negative electrospray ionization mass spectra all gave strong pseudomolecular ions and characteristic fragment ions, however, they showed different fragmentation pathways. In the negative ion MS, the deprotonated molecule showed the base peak with loss of propylene. In the positive ion MS, the protonated molecule usually produced ions from loss of water, amino acid methyl ester, methyl alcohol, uridine and phosphoryl group. These mass spectral fragmentation pathways are helpful to determination of similarphosphoramidates of nucleosides.展开更多
文摘It has been found that Ser His could cleave bovine serum albumin(BSA), with the most suitable pH around 6.0. The kinds of buffers have different influences on the cleavage activity. The phosphate buffer and BR buffer are the most effective. The hydroxyl group of the serine residue is the essential functional group for the cleavage, while the amide bond, imidazole, and carboxyl group of Ser His increase the cleavage activity.
文摘Azido-3′-deoxythymidine(AZT) was the first clinically approved drug against HIV infection, despite its undesirable side reactions, such as bone marrow suppression. In our aim to develop new chemical entity of anti-tumor and anti-HIV, the H-phosphonate 6 of AZT conjugate with diosgenin was synthesized by a tandem transesterification reaction for the first time. There are the merits of easy operation and high yield in the reported method. It could be extended to synthesize other diosgenin phosphonate conjugates such as carbohydrate and peptide.
文摘The tyrosine \%O\%\|phosphorylation \%via\% Atherton\|Todd reaction, which was a classical reaction for phosphorylation amines, was first studied in this paper. Reaction of Boc\|Tyr\|OCH\-3, which was selected as model substrate, with three dialkyl \%H\%\|phosphonate diester in the presence of CCl\-4 and triethylamine produced the corresponding tyrosine \%O\%\|phosphorylation products in a high yield(over 80%). The reaction was conducted in anhydrous THF solution and monitored by \{\}\+\{31\}P NMR and TLC. Then reaction of Boc\|Tyr\|OCH\-3 with a complicated H\|phosphonate diester, \%O\%\|3\|acetylthymidin\|5\|yl \%O\%\|isopropyl \%H\%\|phosphonate diester, also gave a good result and this would be an alternative approach for the synthesis of nucleotide \%O\%\|tyrosine (or tyrosine containing peptide) conjugate. Further, the successful \%O\%\|phosphoration of three tyrosine containing protected dipeptides, Boc\|Tyr\|Val\|OCH\-3, Boc\|Ala\|Tyr\|OCH\-3, Boc\|Tyr\|Tyr\|OCH\-3, with diisopropyl \%H\%\|phosphonate diester demonstrated the effectiveness of the method.
文摘Phosphoramidates of nucleosides are continuing to be an important class of rationally designed therapeutics especially as oligonucleotide analogs employed as antisense and antigene agents. A series of different nucleoside 5’-thiophosphoramidates have recently been synthesized, their electrospray ionization mass specra have been investigated. The positive and negative electrospray ionization mass spectra all gave strong pseudomolecular ions and characteristic fragment ions, however, they showed different fragmentation pathways. In the negative ion MS, the deprotonated molecule showed the base peak with loss of propylene. In the positive ion MS, the protonated molecule usually produced ions from loss of water, amino acid methyl ester, methyl alcohol, uridine and phosphoryl group. These mass spectral fragmentation pathways are helpful to determination of similarphosphoramidates of nucleosides.
