Dongwon Yoo

Sensing behaviour of semconducting metal oxides for the detection of organophosphorus compounds

Abstract Sensing behaviours of doped SnO 2 and ZnO elements have been investigated for the detection of organophosphorus compounds. Among the elements examined, SnO 2 − or ZnO-based elements doped with basic oxides such as CaO and MgO exhibit a promising sensing property to DMMP (dimethyl methylphosphonate). Reasonable sensitivity can be obtained at concentrations of DMMP down to 44 ppb. The test gas was oxidized upon exposure to the oxides. It has been suggested that the basic oxide additives are effective in aiding dissociative adsorption of DMMP on the oxide surface, thus facilitating the oxidation reaction of the test gas.

Lipase catalyzed reaction of L-ascorbic acid with cinnamic acid esters and substituted cinnamic acids

To perform the lipase-catalyzed synthesis of L-ascorbic acid derivatives from plant-based compounds such as cinnamic and ferulic acid under mild reaction conditions, the activities of immobilized Candida ntarctica lipase with different cinnamic acid esters and substituted cinnamic acids were compared. As a result, immobilized C. ntarctica lipase was found to prefer vinyl cinnamic acid to other esters such as allyl-, ethyl-, and isobutyl cinnamic acids as well as substituted cinnamic acids such as p-coumaric acid, caffeic acid, ferulic acid, and sinapic acid. Based on these results, large-scale synthesis of 6-O-cinnamyl-L-ascorbic acid ester was performed using immobilized C. ntarctica lipase in dry organic solvent, resulting in 68% yield (493 mg) as confirmed by 13C-NMR.

A new flow path design for multidimensional protein identification technology using nano-liquid chromatography electrospray ionization mass spectrometry

Multidimensional protein identification technology (MudPIT) is one of the most versatile methods for separating and identifying highly complex peptides or proteins. However, there are still inherent problems resulting from salt in eluent systems and instrumentation with MudPIT. We designed a novel and simple flow path using two-valve system and successfully performed a fully automated peptide analysis using MudPIT coupled with nano-liquid chromatography electrospray ionization mass spectrometry (nLC-ESI-MS). It enables to generate a remarkably stable nanospray during the MudPIT analysis and realize the fully automated MudPIT system. This column arrangement could be easily installed to avoid laborious loading steps and unstable ionization from discontinuous flow. Consequently, the new flow path design for MudPIT system guarantees the detection of more peptides and higher protein coverage in proteome analysis.

CCDC 968616: Experimental Crystal Structure Determination

Related Article: Byeongil Lee, Moonyong Shin, Youngran Seo, Myeong Hak Kim, Hye Ryoung Lee, Jin Seok Kim, Kyu-hyun Chung, Dongwon Yoo, Young Gyu Kim|2018|Tetrahedron|74|130|doi:10.1016/j.tet.2017.11.046

Synthesis of Monomers for Polyamide-type TPEs from Oleic Acid

We have developed the synthetic processes for the monomers of polyamide-type TPEs (thermoplastic elastomers, TPAEs) obtained from vegetable oil. TPAEs have several superior physical properties to those of thermoplastic elastomers (TPEs). From the common starting material, oleic acid, which is commonly found in various vegetable oils, we have synthesized three ω-amino acid monomers (C9, C10 and C11 ω-amino acid) and three α, ω-dicarboxylic acids(C9, C10 and C11 α, ω-dicarboxylic acid) for TPAEs in good yields.

Selective derivatization of nucleotide diphosphate (NDP)-4-keto sugars for electrospray ionization-mass spectrometry (ESI-MS).

Nucleotide diphosphate (NDP) sugars are widely present in antibiotics and glycoconjugates, such as protein- and lipid-linked oligosaccharides, where they act as substrates for glycosyltransferase in eukaryotes and prokaryotes. Among NDP sugars, NDP-4-keto sugars are key intermediates in the synthesis of structurally diverse NDP sugars with different functional groups. However, the structural identification of the NDP-4-keto sugars via mass spectrometry (electrospray ionization-mass spectrometry (ESI-MS)) continues to be a challenge because of the carbonyl group in these sugars interferes with ionization process. In this study, we evaluated various hydroxylamine compounds for the derivatization of NDP-4-keto sugars, so that the detection of the sugars by ESI-MS is more efficient. As a result, O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine was found to be the most effective tagging molecule for the detection of NDP-4-keto sugars without being interfered by original MS. This method can be used for identifying NDP-4-keto sugars such as thymidine diphosphate (TDP)-, adenosine diphosphate (ADP)-, uridine diphosphate (UDP)-, and cytosine diphosphate (CDP)-4-keto sugars as well as new NDP-4-keto-dehydratases.