• YAKHAK HOEJI
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• v.43 no.6
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• pp.743-750
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• 1999

Human and bovine dopamine transporters (DAT) demonstrate discrete functional differences in the dopamine (DA) transport and cocaine binding. The functional analyses on the chimeras of human and bovine DAT have revealed that the region from the $133^{rd}{\;}to{\;}186^{th}$ residue(encompassing the $3^{rd}$ trans-membrane domain (TM) is responsible for the substrate transport and cocaine binding. The present studies have been done to find out the specific amino acid(s) which is essential for the binding of cocaine to DAT by interchanging the amino acids in that region between human and bovine DAT. When isoleucine, the $152^{nd}$ residue of chimera B3 (bovine DAT sequence) was transformed back to valine, the human DAT residue at the identical position, the cocaine binding was remarkably recovered to 98% of the human DAT values. In addition, the cocaine binding of the human DAT was decreased by 57% by substituting isoleucine for valine at position 152. When isoleucine at position 152 of the chimera B3 was converted to the other amino acids to provide an possible molecular basis for the functional role of the $152^{nd}$ residue, only the conversion to alanine among acids tested significantly the cocaine by 34%, but these effect were not as much as those by the conversion to valine. In conclusion, valine at position 152 is a crucial amino acid for the interaction of cocaine to the DAT.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.06a
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• pp.21-38
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• 1999

Herbicide is an essential agricultural chemical in the modern agriculture. Due to its bioactivity, however, risk of herbicide use against non-target organisms should be seriously considered. Among the unfavorable aspects given by herbicide, the residue is the most important because herbicide residue in soil and agricultural product is closely related to human safety. The residue in soil and crop is dependent on conditions of soil, weather, herbicide use and crop cultivation, etc. In general, the residue in soil or agricultural product in Korea is known to be not serious at this moment, except for some problems like carry-over effect on succeeding crops. To secure safety of herbicide use for the health, soil ecology and other environment, researches on herbicide residue including monitoring survey should be done more frequently and extensively. Safety guide for herbicide usage should be kept by farmers and development of long toxic herbicide should be accelerated.

• BMB Reports
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• v.36 no.4
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• pp.409-416
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• 2003

The isoform 1 of cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) from Paenibacillus sp. A11 was purified by a preparative gel electrophoresis. The importance of histidine, tryptophan, tyrosine, and carboxylic amino acids for isoform 1 activity is suggested by the modification of the isoform 1 with various group-specific reagents. Activity loss, when incubated with diethylpyrocarbonate (DEP), a histidine modifying reagent, could be protected by adding 25 mM methyl-$\beta$-cyclodextrin substrate prior to the modification. Inactivation kinetics of isoform 1 with DEP resulted in second-order rate constants ($k_{inactivation}$) of $29.5\;M^{-1}s^{-1}$. The specificity of the DEP-modified reaction for the histidine residue was shown by the correlation between the loss of isoform activity and the increase in the absorbance at 246 nm of N-carbethoxyhistidine. The number of histidines that were modified by DEP in the absence and presence of a protective substrate was estimated from the increase in the absorbance using a specific extinction coefficient of N-carbethoxyhistidine of $3,200\;M^{-1}cm^{-1}$. It was discovered that methyl-$\beta$-CD protected per mole of isoform 1, two histidine residues from the modification by DEP. To localize essential histidines, the native, the DEP-modified, and the protected forms of isoform 1 were digested by trypsin. The resulting peptides were separated by HPLC. The peptides of interest were those with $R_t$ 11.34 and 40.93 min. The molecular masses of the two peptides were 5,732 and 2,540 daltons, respectively. When the data from the peptide analysis were checked with the sequence of CGTase, then His-140 and His-327 were identified as essential histidines in the active site of isoform 1.

• BMB Reports
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• v.50 no.7
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• pp.373-378
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• 2017

The Jun activation-domain binding protein 1 (Jab1) induces p53 nuclear export and cytoplasmic degradation, but the underlying mechanism is poorly understood. Here, we show that phosphorylation at the threonine 155 residue is essential for Jab1-mediated p53 nuclear export. Jab1 stimulated phosphorylation of p53 at T155 was inhibited by curcumin, an inhibitor of COP9 signalosome (CSN)-associated kinases. The T155E mutant, which mimics phosphorylated p53, exhibited spontaneous cytoplasmic localization in the absence of Jab1. This process was prevented by leptinomycin B (LMB), but not by curcumin. The substitution of threonine 155 for valine (T155V) abrogated Jab1-mediated p53 nuclear export, indicating that phosphorylation at this site is essential for Jab1-mediated regulation of p53. Although T155E can be localized in the cytoplasm in the absence of Mdm2, the translocation of T155E was significantly enhanced by ectopic Hdm2 expression. Our data suggests that Jab1-mediated phosphorylation of p53 at Thr155 residue mediates nuclear export of p53.

• BMB Reports
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• v.32 no.3
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• pp.254-258
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• 1999

The NADPH-dependent succinic semialdehyde reductase is one of the key enzymes in the brain GABA shunt, and it catalyzes the formation of the neuromodulator $\gamma$-hydroxybutyrate from succinic semi aldehyde. This enzyme was inactivated by diethylpyrocarbonate (DEP) with the second-order rate constant of $1.1{\times}10^3\;M^{-1}min^{-1}$ at pH 7.0, $25^{\circ}C$, showing a concomitant increase in absorbance at 242 nm due to the formation of N-carbethoxyhistidyl derivatives. Complete inactivation of succinic semialdehyde reductase required the modification of five histidyl residues per molecule of enzyme. However, only one residue was calculated to be essential for enzyme activity by a statistical analysis of the residual enzyme activity. The inactivation of the enzyme by DEP was prevented by preincubation of the enzyme with the coenzyme NADPH but not with the substrate succinic semialdehyde. These results suggest that an essential histidyl residue involved in the catalytic activity is located at or near the coenzyme binding site of the brain succinic semialdehyde reductase.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.277-284
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• 1999

To confirm the food quality of conventionally processed fish extracts, protein quality of boiled crucian carp(Carassius carassius) and bastard halibut(Paralichthys olivaceus) extracts and their residues were evaluated. For the both fish extracts, some of the essential amino acids were lowered significantly but two times more proline and glycine were detected in extracts than those in raw fish meats. Boiling(100oC, 5 hours) caused 1.8(crucian carp)~2.4(bastard halibut) times more total free amino acid contents in fish extracts as compared to those in original fish meats. Taurine, glutamic acid, proline, lysine, and ammonia were the predominant free amino acids released in fish extracts. In vitro digestibility of boiled fish extracts were lower at a level of 4~6% than those of raw fish meats. Fish extraction residue had a higher in vitro digestibility and had a 60% lower level of TI than that of original fish meats. 18(bastard halibut)~ 24%(crucian carp) of available lysine was reduced in boiled fish extracts but a remarkable variation was not noted between extracts and residues. PERs and NPRs of fish extracts were significantly lower than those of casein, while those values of extraction residue were slightly higher as compared to those of control(ANRC casein). In vivo apparent digestibility exhibited a similar trend to in vitro digestibility. Hematological properties in serum of rat fed with fish extracts and residue were not changed significantly but the serum cholesterol concentration were reduced in rats fed fish extraction residue comparing with those of control. These results suggest that body weight loss due to fish extracts may not affect physiological changes.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.282-286
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• 1990

To extract insoluble proteins of soymilk residue by microorganism the soymilk residue was treated with crude enzyme solution from Bacillus subtilis IAM 1071 natto. Optimum conditions of pH, temperature, and digestion time were determined, and amino acid composition of the extract was obtained at $45^{\circ}C$. Under optimum conditions, the extractability with natto reached to 65% in 15hrs. The contents of essential amino acids of extract were high and specially, S-containing amino acids including methonine and cysteine and Lysine content were high.

• Journal of Microbiology
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• v.39 no.3
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• pp.149-153
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• 2001

The electron transfer reaction is one of the most essential processes of life. Not only does it provide the means of transforming solar and chemical energy into a utilizable form for all living organisms, it also extends into a range of metabolic processes that support the life of a cell. Thus, it is of great interest to understand the physical basis of the rates and reduction potentials of these reactions. To identify the major determinants of reduction potentials in redox proteins, we have chosen the simplest electron transfer protein, rubredoxin, a small (52-54 residue) iron-sulfur protein family, widely distributed in bacteria and archaea. Rubredoxins can be grouped into two classes based on the correlation of their reduction potentials with the identity of residue 44; those with Ala44 (ex: Pyrococcus furiosus) have reduction potentials that are ∼50 mV higher than those with Va144 (ex: Clostridium pasteurianum). Based on the crystal structures of rubredoxins from C. pasteurianum and P. furiosus, we propose the identity of residue 44 alone determines the reduction potential by the orientation of the electric dipole moment of the peptide bond between 43 and 44. Based on 1.5 $\AA$ resolution crystal structures and molecular dynamics simulations of oxidized and reduced rubredoxins from C. pasteurianum, the structural rearrangements upon reduction suggest specific mechanisms by which electron transfer reactions of rubredoxin should be facilitated.

• BMB Reports
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• v.29 no.4
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• pp.321-326
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• 1996

Spinach glycolate oxidase was subjected to a series of chemical modifications aimed at identifying amino acid residues essential for catalytic activity. The oxidase was reversibly inactivated by treatment with pyridoxal 5'-phosphate (PLP). The inactivation by PLP was accompanied by the appearance of an absorption peak of around 430 nm, which was shifted to 325 nm upon reduction with $NaBH_4$. After reduction, the PLP-treated oxidase showed a fluorescence spectrum with a maximum of around 395 nm by exciting at 325 nm. The substrate-competitive inhibitors oxalate and oxaloacetate provided protection against inactivation of the oxidase by PLP. These results suggest that PLP inactivates the enzyme by fonning a Schiff base with lysyl residue(s) at an active site of the oxidase. The enzyme was also inactivated by tryptophan-specific reagent N-bromosuccinimide (NBS). However, competitive inhibitors oxalate and oxaloacetate could not protect the oxidase significantly against inactivation of the enzyme by NBS. The results implicate that the inactivation of the oxidase by NBS is not directly related to modification of the tryptophanyl residue at an active site of the enzyme. Treatments of the oxidase with cysteine-specific reagents iodoacetate, silver nitrate, and 5,5'-dithiobis-2-nitrobenzoic acid did not affect significantly the activity of the enzyme.

• Journal of Biosystems Engineering
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• v.33 no.2
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• pp.136-141
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• 2008

Fecal contaminations on poultry carcasses, not easily discemable by human eyes, are potential harbor sites of pathogenic Escherichia Coli (E. coli O157:H7). Development of sensitive detection methods for fecal contamination is essential to ensure safe production of poultry products. Fluorescence has been shown to be very sensitive in detecting fecal and other biological substances that can harbor pathogens. In this study, fluorescence excitation-emission spectra of poultry fecal matter were compared with spectra for poultry skin and meat. Results indicated that the combinations of fluorescence intensities at the wavelength of 520 nm, 579 nm, 625 nm, and 635 nm with 411 nm excitation showed above 97% accuracy for differentiation of the contaminants from poultry tissues. Excitation and emission bands determined could be used for constructing a real-time fluorescence imaging device for detection of harmful residues on poultry carcasses.