10159-53-2Relevant articles and documents
The partitioning of phosphoramide mustard and its aziridinium ions among alkylation and P-N bond hydrolysis reactions
Shulman-Roskes, Ellen M.,Noe, Dennis A.,Gamcsik, Michael P.,Marlow, Allison L.,Hilton, John,Hausheer, Frederick H.,Colvin, O. Michael,Ludeman, Susan M.
, p. 515 - 529 (1998)
NMR (1H and 31P) and HPLC techniques were used to study the partitioning of phosphoramide mustard (PM) and its aziridinium ions among alkylation and P-N bond hydrolysis reactions as a function of the concentration and strength of added nucleophiles at 37 °C and pH 7.4. With water as the nucleophile, bisalkylation accounted for only 10-13% of the product distribution given by PM. The remainder of the products resulted from P-N bond hydrolysis reactions. With 50 mM thiosulfate or 55-110 mM glutathione (GSH), bisalkylation by a strong nucleophile increased to 55- 76%. The rest of the PM was lost to either HOH alkylation or P-N bond hydrolysis reactions. Strong experimental and theoretical evidence was obtained to support the hypothesis that the P-N bond scission observed at neutral pH does not occur in the parent PM to produce nornitrogen mustard; rather it is an aziridinium ion derived from PM which undergoes P-N bond hydrolysis to give chloroethylaziridine. In every buffer studied (bis-Tris, lutidine, triethanolamine, and Tris), the decomposition of PM (with and without GSH) gave rise to 31P NMR signals which could not be attributed to products of HOH or GSH alkylation or P-N bond hydrolysis. The intensities of these unidentified signals were dependent on the concentration of buffer.
Improving nature's enzyme active site with genetically encoded unnatural amino acids
Jackson, Jennifer C.,Duffy, Sean P.,Hess, Kenneth R.,Mehl, Ryan A.
, p. 11124 - 11127 (2006)
The ability to site-specifically incorporate a diverse set of unnatural amino acids (>30) into proteins and quickly add new structures of interest has recently changed our approach to protein use and study. One important question yet unaddressed with unnatural amino acids (UAAs) is whether they can improve the activity of an enzyme beyond that available from the natural 20 amino acids. Herein, we report the >30-fold improvement of prodrug activator nitroreductase activity with an UAA over that of the native active site and a >2.3-fold improvement over the best possible natural amino acid. Because immense structural and electrostatic diversity at a single location can be sampled very quickly, UAAs can be implemented to improve enzyme active sites and tune a site to multiple substrates.
Synthesis, Activation, and Cytotoxicity of Aldophosphamide Analogues
Borch, Richard F.,Valente, Ronald R.
, p. 3052 - 3058 (2007/10/02)
A series of perhydrooxazine analogues of aldophosphamide has been prepared, and their 31P NMR kinetics and in vitro cytotoxicity have been evaluated.These compounds were developed on the basis of the idea that ring opening and tautomerization to an enamine intermediate might provide a mechanistic alternative to the β-elimination reaction for release of phosphoramide mustard.The 4,4,6-trimethyltetrahydro-1,3-oxazine moiety was selected on the basis of its rapid rate of iminium ion generation and relatively slow rate of hydrolysis.These analogues underwent phosphorodiamidate release by three distinct mechanisms: hydrolysis to aldophosphamide and subsequent β-elimination; cyclization to produce the 4-hydroxycyclophosphamides, which release phosphorodiamidate by ring opening and elimination; and tautomerization to the enamine with rapid expulsion of phosphorodiamidate.Kinetic studies demonstrated that hydrolysis to the aldehyde contributed minimally to the overall activation process and that the enamine pathway represented the major route of activation.For those analogues that could undergo cyclization this pathway competed effectively with enamine release, and these analogues were essentially equivalent to their 4-hydroxycyclophosphamide counterparts in cytotoxicity.A series of tetra-N-substituted phosphorodiamidates that cannot undergo cyclization was prepared to explore the effects of cyclization on the cytotoxicity of these analogues.The tetrakis(chloroethyl)phosphorodiamidates were highly potent in vitro against both cyclophosphamide-sensitive and -resistant L1210 and P388 cell lines, and one of these analogues had significant antitumor activity against L1210 leukemia in vivo.These results demonstrate that the enamine mechanism provides a viable pathway for delivery of phosphorodiamidates and that this approach can be used to deliver phosphorodiamidates that are non-cross-resistant in cyclophosphamide-resistant cell lines.
