Determination of free and total homocysteine in human plasma by high-performance liquid chromatography with fluorescence detection.

Analysis of glutathione: implication in redox and detoxification.

Rapid high-performance liquid chromatographic assay for total homocysteine levels in human serum.

The diversity of application of the thiol drug NAC in both the experimental setting, as a tool for the study of the mechanisms and consequences of oxidative stress, and the clinical setting, as a therapeutic agent, clearly reflects the central role played by the redox chemistries of the group XVI elements, oxygen and sulfur, in biology. As our understanding of such redox processes increases, particularly their roles in specific pathophysiological processes, new avenues will open for the use of NAC in the clinical setting. As a drug, NAC represents perhaps the ideal xenobiotic, capable of directly entering endogenous biochemical processes as a result of its own metabolism. Thus, it is hoped that the experience gained with this unique agent will help in future efforts to design antioxidants and chemoprotective principles which are able to more accurately utilize endogenous biochemical processes for cell- or tissue-specific therapy.

N-acetylcysteine: pharmacological considerations and experimental and clinical applications.

A series of homologous L-amino acid, D-amino acid, and both parallel and anti-parallel (retro) sequence N-substituted glycine peptide and peptoid oligomers were prepared and incubated with a series of enzymes representative of the major classes of proteases. Each respective L-amino acid containing peptide sequence was readily cleaved by the appropriate enzyme, namely Ac-L-ala-L-leu-L-phe-L-ala-L-leu-L-arg-NH2 by chymotrypsin, Ac-L-ala-L-ala-L-ala-L-leu-L-phe-L-arg-NH2 by elastase, Ac-L-ala-L-phe-L-glu-L-leu-L-ala-L-ala-NH2 by papain, Z-L-ala-L-his-L-phe-L-phe-L-arg-L-leu-NH2 by pepsin, Ac-L-phe-L-ala-L-arg-L-ala-L-arg-L-asp-NH2 by trypsin, and Ac-L-ala-L-tyr-Lala-L-phe-OH for carboxypeptidase A. In contrast, equivalent D-amino acid containing and N-substituted glycine containing oligomers were cleaved minimally or not at all by the respective enzymes. The N-substituted glycine peptoids represent a new class of combinatorial diversity for lead discovery with improved pharmaceutical characteristics relative to L-amino acid containing peptides. © 1995 Wiley-Liss, Inc.

Comparison of the proteolytic susceptibilities of homologous L-amino acid, D-amino acid, and N-substituted glycine peptide and peptoid oligomers

A novel fluorogenic reagent for thiols : ammonium 7-fluorobenzo-2-oxa-1, 3-diazole-4-sulfonate

High-performance liquid chromatography and fluorometric detection of biologically important thiols, derivatized with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate (SBD-F)

Further studies on the reaction of amines and proteins with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole

Reaction of amines of biological importance with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole

A simple, sensitive and reliable method for the detection of cystine-containing peptides has been developed. A peptide bridged with a disulfide bond was reduced and cleaved with tributylphosphine, and then coupled with a thiol specific reagent, ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate, under alkaline conditions. After incubation at 60 degrees C for 1 h, the fluorescent derivative formed was measured with excitation at 385 nm and emission at 515 nm. The intensity of fluorescence labeled to the peptide was very stable and the peptide containing disulfide was quantitatively determined in the range of 100 pmol to 10 nmol, when oxidized glutathione was used as a standard. This method was very useful for specific detection of cystine-containing peptides in the column effluents on reverse phase high performance liquid chromatography.

Toshimasa Toyo'oka

Papers

A novel fluorogenic reagent for thiols : ammonium 7-fluorobenzo-2-oxa-1, 3-diazole-4-sulfonate

High-performance liquid chromatography and fluorometric detection of biologically important thiols, derivatized with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate (SBD-F)

Further studies on the reaction of amines and proteins with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole

Reaction of amines of biological importance with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole

Application of a Fluorogenic Reagent, Ammonium 7-Fluorobenzo-2-Oxa-1, 3-Diazole-4-Sulfonate for Detection of Cystine-Containing Peptides