Quantitation and characterization of glutathionyl haemoglobin as an oxidative stress marker in chronic renal failure by mass spectrometry.

Objectives: Glutathionyl haemoglobin (GS-Hb) belonging to the class of glutathionylated proteins has been investigated as a possible marker of oxidative stress in different chronic diseases. The purpose of this study was to examine whether glutathionyl haemoglobin can serve as an oxidative stress marker in non-diabetic chronic renal failure patients on different renal replacement therapies (RRT) through its quantitation, and characterization of the specific binding site of glutathione in haemoglobin molecule by mass spectrometric analysis.

Design And Methods: The study group consisted of non-diabetic chronic renal failure patients on renal replacement therapy (RRT): hemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and renal allograft transplant (Txp) patients.

Sequencing of T-superfamily conotoxins from Conus virgo: pyroglutamic acid identification and disulfide arrangement by MALDI mass spectrometry.

De novo mass spectrometric sequencing of two Conus peptides, Vi1359 and Vi1361, from the vermivorous cone snail Conus virgo, found off the southern Indian coast, is presented. The peptides, whose masses differ only by 2 Da, possess two disulfide bonds and an amidated C-terminus. Simple chemical modifications and enzymatic cleavage coupled with matrix assisted laser desorption ionization (MALDI) mass spectrometric analysis aided in establishing the sequences of Vi1359, ZCCITIPECCRI-NH(2), and Vi1361, ZCCPTMPECCRI-NH(2), which differ only at residues 4 and 6 (Z = pyroglutamic acid).

Solvation dynamics of a protein in the pre molten globule state.

The nature of solvent molecules around proteins in native and different non-native states is crucial for understanding the protein folding problem. We have characterized two compact denatured states of glutaminyl-tRNA synthetase (GlnRS) under equilibrium conditions in the presence of a naturally occurring osmolyte, l-glutamate. The solvation dynamics of the compact denatured states and the fully unfolded state has been studied using a covalently attached probe, acrylodan, near the active site.

Synthetic studies on amphidinolide B1.

[structure: see text]. The syntheses of three fragments, 2, 3, and 4, of amphidinolide B1 have been accomplished. The 1,3-isomerization of allylic alcohol 10 was accomplished via rhenium oxo catalysis and has been applied successfully in the synthesis.

Stereoselective assembly of a 1,3-diene via coupling between an allenic acetate and a (B)-alkylborane: synthetic studies on amphidinolide B1.

The preparation of three fragments for the total synthesis of amphidinolide B1 has been described. The C16 stereochemistry was set by asymmetric allylic alkylation. C21 and C25 stereogenic centers were set by an enantioselective/diastereoselective double allylation reaction.

Developing microcolin A analogs as biological probes.

Three microcolin A and B analogs have been synthesized. Their biological activity profiles were evaluated against several cell lines, revealing the existence of a structural determinant whose role in mediating the antiproliferative effect of the microcolins has heretofore gone unrecognized. While previously described as potent immunosuppressive natural products, we found that these microcolin analogs possessed no selective cytotoxicity when comparing immune cell versus nonimmune cell proliferation.

Chemical genetic control of protein levels: selective in vivo targeted degradation.

Genetic loss of function analysis is a powerful method for the study of protein function. However, some cell biological questions are difficult to address using traditional genetic strategies often due to the lack of appropriate genetic model systems. Here, we present a general strategy for the design and syntheses of molecules capable of inducing the degradation of selected proteins in vivo via the ubiquitin-proteasome pathway.

Stereocontrol in organic synthesis using silicon-containing compounds. Studies directed towards the synthesis of ebelactone A.

Several approaches to the synthesis of ebelactone A 2 are described, culminating in the synthesis of the benzenesulfonate of 2-epi-ebelactone A 161. All the approaches were based on three fragments A, B and C, originally defined in general terms in, but eventually used as the aldehyde 72, the allenylsilane 3 and the aldehyde 139, respectively. They were joined, first B with C, and then B+C with A.

Solvation change and ion release during aminoacylation by aminoacyl-tRNA synthetases.

Discrimination between cognate and non-cognate tRNAs by aminoacyl-tRNA synthetases occurs at several steps of the aminoacylation pathway. We have measured changes of solvation and counter-ion distribution at various steps of the aminoacylation pathway of glutamyl- and glutaminyl-tRNA synthetases. The decrease in the association constant with increasing KCl concentration is relatively small for cognate tRNA binding when compared to known DNA-protein interactions.

Glutamate counteracts the denaturing effect of urea through its effect on the denatured state.

The urea induced equilibrium denaturation behavior of glutaminyl-tRNA synthetase from Escherichia coli (GlnRS) in 0.25 m potassium l-glutamate, a naturally occurring osmolyte in E. coli, has been studied.

Stereocontrolled total synthesis of (-)-ebelactone A.

[structure: see text] The highly stereocontrolled hydroboration of an alkene, a subsequent Suzuki-Miyaura cross-coupling reaction, a silylcupration on a nonterminal acetylene, and an iododesilylation were the key steps in a convergent total synthesis of (-)-ebelactone A.