Chulyoung Kim

Solvent-free enzymatic synthesis of alitame precursor using eutectic substrate mixtures.

N-benzyloxycarbonyl-L-aspartic acid ethyl ester-D-alanine amide, a derivative of alitame, was synthesized from a eutectic mixture of the substrates N-benzyloxycarbonyl-L-aspartic acid diethyl ester and D-alanine amide using alpha-chymotrypsin. The hydrophilic solvents DMSO and MEA were found to be the best adjuvants for formation of a eutectic substrate mixture. A low eutectic temperature of 27 degrees C was obtained for the substrate mixture containing 9% DMSO, 18% MEA, and 12% water. Under these conditions a conversion yield of 70.3% (mol/mol) was obtained at 37 degrees C. The optimum molar ratio of the acyl acceptor D-alanine amide and the acyl donor N-benzyloxycarbonyl-L-aspartic acid diethyl ester was 1:1.

Synthesis of kyotorphin precursor from eutectic mixtures catalysed by α-chymotrypsin

The kyotorphin precursor, N-carbobenzoxyl-l-tyrosine-l-arginine amide (N-CBZ-l-Tyr-l-ArgNH2), was synthesized from N-CBZ-l-tyrosine ethyl ester (N-CBZ-l-TyrOEt) and l-arginine amide (l-ArgNH2) by using α-chymotrypsin. Eutectic mixtures were formed by mixing the substrates in the presence of water and/or organic solvents as adjuvants. The eutectic temperature was obtained with a 0.45 l-ArgNH2 mole fraction. It was lowered to 23 °C by addition of 10% (v/w) water and 5% (v/w) dimethyl formamide, thus maintaining homogeneous liquid states at the reaction temperature of 30 °C. After 9 h the solutions became solidified and no further reaction took place. Approximately 90% (mol/mol) conversion was achieved from the substrate mixtures with substrate contents responsible for more than 80% (w/w) of the total mixture.

An Economic Rationale for Dismissing Low-Quality Experts in Trial

The history of the admissibility standard for expert testimony in American courtrooms reveals that the standard has gradually increased to a high level since a series of important decisions by the Supreme Court. Whether such a stringent standard for expert testimony is beneficial or detrimental to the American justice system is still under fierce debate, but there has been scant economic analysis of this issue. This paper attempts to fill the gap by presenting a game-theoretic argument showing that a stringent admissibility standard operates to increase the judicial decisions accuracy under certain situations. More precisely, when the judge faces uncertainty regarding an experts quality, the admissibility standard may provide the judge with information about the quality of expert testimony, thereby increasing the accuracy of the judicial decision by mitigating the judges inference problem. I show the ways in which this effect dominates at trial and discuss related issues.

Minimum Asset and Liability Insurance Requirements on Judgment-Proof Individuals When Harm Is Endogenous

Minimum asset requirements are an increasingly common form of regulation intended to motivate better decision making by individuals who participate in potentially harmful activities. Shavell (2005) studied the optimality of this type of regulation within a framework in which an individual can influence the probability of an accident but not the magnitude of the resultant harm. We reinvestigate Shavells model for the opposite accident scenario, in which an individual can influence the magnitude of harm but not the probability of an accident, and find policy implications different than Shavells. In particular, we show that in certain situations it could be optimal to completely ban judgment-proof individuals from participating in a potentially harmful activity. We also examine the effect of liability insurance, and find that regulatory authorities should tighten standards relative to the pure asset requirement and that liability insurance increases social welfare.