Yuping Feng

Studies on cleavage of DNA by N-phosphoryl branched peptides

It was found that Nalpha,Nepsilon-di[N-(O,O-diisopropyl)phosphoryl-L-leucy]-L-lysyl-methyl ester (1) and Nalpha,Nepsilon-di[N-(O,O-diisopropyl)phosphoryl-L-phenylalanyl]-L-lysyl-methyl ester (2) could cleave supercoiled DNA such as PUC19 efficiently in 40 mM Britton-Robinson buffer. The cleavage activities for both were investigated by agarose gel electrophoresis. The T4 ligase experiments implied that the cleavage of DNA occurs via a hydrolytic path. The results showed that the cleavage reaction of DNA is dependent on the value of pH and ionic strength in the solution. DNA cleavage is more efficient by N-phosphoryl branched peptide 2 than by N-phosphoryl branched peptide 1. The experiments also show that hydrolysis of DNA by N-phosphoryl branched peptide 1 was accelerated in the presence of Mg2+ or Zn2+ ions. The interactions of DNA with N-phosphoryl branched peptides were also characterized by melting temperature measurements and circular dichroism (CD) techniques. On the basis of experimental data, the possible mechanism of interactions between DNA with N-phosphoryl branched peptides was discussed.

31P-13C, 31P-1H SPIN-SPIN COUPLING AND STRUCTURAL ASSIGNMENT AND CONFORMATIONAL ANALYSIS OF EPIMERIC THYMIDINE-3′-YL BENZOIN PHOSPHATES

Abstract A pair of epimeric thymidine-3′-yl benzoin phosphates 3 were produced from the ester exchange reaction of oxyphosphorane 1 with thymidine 2. Their structures were identified by using the 1H, 13C and 31P NMR spectra. The chemical bonds between the ribose 3′-C and a-C atoms to the phosphoryl group were confirmed by 31P-′13C and 31P-1H spin-spin coupling. The stereosensitive three-bond coupling constants 3JP-c and 3JP-H in each diastereomer of 3 have been measured, and used for an estimation of trans and gauche conformational analysis. The relative estimated dihedral angle of P-O-C-H was discussed.

A facile approach for the synthesis of α-halogenated alkylidenediphosphonates by reaction of alkyllithium with chlorophosphate and halogen reagent

Alkyllithium reacts with chlorophosphate to generate the α -lithio- alkylidenediphosphonate, which further reacts with halogen reagents to afford corresponding α -halogenated alkylidenediphosphonates.

Hydrolysis of DNA by N-Phosphoryl Branched Peptide

A N-phosphoryl branched peptide (DIPP-Leu) 2 -Lys-OCH 3 was found to efficiently cleave double-strand DNA such as PUC19 and Lambda DNA at pH 8.5 in 100 mM Tris-HCl buffer. The T4 ligase experiment implied that the DNA cleavage occurs via a hydrolytic path.

13C Nuclear Magnetic Resonance Studies of the Conformations of Serine‐3′‐ and 5′‐Thymidine Monophosphate Conjugates

The differences in the backbone conformation between O‐thymidine‐3′‐(1) and 5′‐yl O‐alkyl N‐phosphoryl serine methyl esters (2) have been investigated by solution 13C NMR spectroscopy. The stereo‐sensitive vicinal 31P–13C coupling constants were measured and used in the conformational analysis for the P–O5′–C5′, P–O3′–C3′, and P–N–Cα bonds. Three‐dimensional structural characteristics of dephosphorylation reactions of Compounds are also discussed.

STUDIES ON THE CONFORMATIONS OF O-URIDINE-5′-YL O-ALKYL N-PHOSPHORYL SERINE METHYL ESTERS BY NUCLEAR MAGNETIC RESONANCE (NMR) AND CIRCULAR DICHROISM (CD)

Abstract The conformations of O-uridine-5′-yl O-alkyl N-phosphoryl serine methyl esters (1) and (2) have been investigated by nuclear magnetic resonance (NMR) and circular dichroism (CD) techniques, Nuclear Overhauser effect (NOE) measurements and CD studies revealed that the glycosyl bonds in both compounds favor the syn orientation. The stereosensitive 31P-13C coupling constants were also measured and used for the analysis of the trans and gauche conformations. The three-dimensional structural characteristics of compounds (1) and (2) were discussed.