• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1291-1294
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• 2002

Various racemic N-protected ${\alpha}-amino$ acids such as N-t-BOC-(tert-butoxycarbonyl), N-CBZ-(benzyloxycarbonyl) and N-FMOC-(9-fluorenylmethyloxycarbonyl) ${\alpha}-amino$ acids were resolved as their anilide and 3,5-dimethylanilde derivatives on an HPLC chira l stationary phase (CSP) developed by modifying a commercial (S)-leucine CSP. The chromatographic resolution results were compared to those on the commercial (S)-leucine CSP. The resolutions were greater on the modified CSP than those on the commercial CSP with only one exception, the resolution of N-t-BOC-phenylglycine anilide. In addition, the chromatographic resolution behaviors were quite consistent except for the resolution of N-protected phenylglycine derivatives, the (S)-enantiomers being retained longer. Based on the chromatographic resolution behaviors and with the aid of CPK molecular model studies, we proposed a chiral recognition mechanism for the resolution of N-protected ${\alpha}-amino$ acid derivatives. However, for the resolution of N-protected phenylglycine derivatives, a second chiral recognition mechanism, which competes in the opposite sense with the first chiral recognition mechanism, was proposed. The two competing chiral recognition mechanisms were successfully used in the rationalization of the chromatographic behaviors for the resolution of N-protected phenylglycine derivatives.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.419-428
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• 2010

Here we describe a fast and rapid technique for preparation of amino acid hydrazide as well as peptide hydrazide derivatives using diisopropylcarbodiimide (DIC)/1-hydroxybenzotriazoles (HOXt) (X = A or B) under microwave irradiation employing a multimode reactor (Synthos 3000 Aton Paar, GmbH, 1400 W maximum magnetron). A comparison between conventional and microwave irradiation was described. The microwave methodology is rapid, convenient, proceeds under mild conditions. Diisopropylcarbodiimide (DIC)/7-aza-1-hydroxybenzotriazole (HOAt) always gave much better yield (95 - 98%) and purity than diisopropylcarbodiimide (DIC)/1-hydroxybenzotriazole (HOBt).

• Korean Journal of Microbiology
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• v.5 no.2
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• pp.79-85
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• 1967

Kim, Jong Hyup., (Div. of Biology, Atomic Energy Research Institute,Korea.;) Studies on the Cellulor Metabolism in Microorganisms as influenced by Gamma-irradiation(III): On the Changes of Free Amino acid Pool and content of Protein in Yeast clls irradiated by .gamma.-ray. 1. The strain of Saccharomyces cerevisiae had been cultured synchronously in aerobic condition and irradiatel by gamma-ray from the source of cobalt-60. Drying in vacuum oven at $90^{\circ}C$ C over 12 hours, then changes of protein content (Kjeldahl) and free amino acid pool have been assayed with use of spectrophotometer. Results obtained were compared with those of unirradiated normal cells. 2. It is proved that amount of protein content in the irradiated cells increases to seven percent more than those of normal cells in the same weight of dried samples. It seems like carbohydrate breakown had been stimulated by irradiation and that relative contents of protein shows higher values than those of normal in the same weight of samples. 3. The amount of free amino acid pool in the irradiated cells shows less value about ten percent than those of normal cells, and rate of decreasing is also weak than those of standard reagent solution of amino acid. We may assume that free amino acid pool would be protected against radiation damage in living cells and more stable than in vitro. 4. The component of free amino acid pool have been assayed on second dimensional paper chromatogram, and the identified amino acids are as follows; aspartic acid, serine, glutamic acid, cystine, lysine, glycine, threonine, histidine, arginine, tyrosine, phenylalanine, valine and leucine. 5. Distributional presence of free amino acids are identical to that of normal cells except arginine, it is cosumable that radiation effect is univerlsal to all amino acid. However it is obvious that there are differences in radiolabilities of amino acids in irradiated cells.

• BMB Reports
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• v.31 no.3
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• pp.258-263
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• 1998

Acetolactate synthase (ALS) is the common enzyme in the biosynthetic pathways leading to leucine, valine, and isoleucine. Tobacco ALS was expressed in E. coli and purified to homogeneity. The recombinant tobacco ALS was inactivated by thiol-specific reagents, N-ethylmaleimide (NEM) and 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB). Inactivation of the ALS by NEM followed pseudo-first order kinetics and was first order with respect to the modifier. The substrate pyruvate protected the enzyme against the inactivation by NEM and DTNB. Extrapolation to complete inactivation of the enzyme by DTNB showed modification of approximately 2 out of 4 total cysteinyl residues (or 2 cysteinyl and 1 cysteinyl residues), with approximately 1 residue protected by pyruvate. The tobacco ALS was also inactivated by the tryptophanspecific reagent, N-bromosuccinimide (NBS), and was similarly protected by pyruvate. The kinetics of the inactivation was first-order with respect to NBS. The present data suggest that cysteinyl and tryptophanyl residues play a key role in the catalytic function of the enzyme.

• Journal of Animal Science and Technology
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• v.52 no.6
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• pp.499-504
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• 2010

This study was conducted to determine the effects of ruminally protected amino acid-enriched fatty acids (RPAAFA) on body weight gain, feed intake and carcass characteristics of fattening Hanwoo cows. Twenty eight Hanwoo cows, $6.0{\pm}1.7$ years old and weighing an average of $463.2{\pm}77.6\;kg$, were used for 4 months. Animals were fed a basal diet supplemented with RPAAFA at 0 g (control) and 100 g (treatment), respectively. Average daily gain, dry matter intake and feed conversion ratio were not different among the control and treatment. The supplementation of RPAAFA did not affect carcass weight and rib eye areas. Quality grade score ($1^{++}$, $1^+$ and 1) for treatment was higher in RPAAFA supplemented group compared with the control, whereas no differences appeared in meat color, fat color, texture and maturity. Thus present results indicate that supplementation of RPAAFA may be recommended for producing high quality beef from fattening Hanwoo cows.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.669-679
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• 2021

This study was conducted to evaluate the effects of rumen-protected amino acid (RPAA) prototypes, which were chemically synthesized, on in vitro rumen fermentation and protection rate outcomes. Several RPAA prototypes were incubated with timothy hay and concentrate. Treatments consisted of 1) control (CON; no RPAA prototype supplement), and prototypes of 2) 0.5% RP-methionine (RPMet), 3) 0.5% RP-tryptophan (RPTrp), 4) 0.5% RP-valine (RPVal), 5) 0.5% RP-phenylalanine (RPPhe), 6) 0.5% RP-leucine (RPLeu), 7) 0.5% RP-histidine (RPHis), 8) 20% RPMet, and 9) 20% RPTrp (w·w^-1 feed). The inoculum (50 mL) prepared with rumen fluid and McDougall's buffer (1 : 4) was dispensed in individual serum bottles and was anaerobically incubated for 0, 6, and 24 h at 39℃ in triplicate. The dry matter degradability did not differ among the groups, except for the 20% RPMet and the 20% RPTrp treatments at 6 and 24 h. The total volatile fatty acid concentration in the 20% RPMet was higher (p < 0.05) than the rest of the groups at 6 h, and 20% RPMet showed the highest molar proportion of acetate, whereas the lowest proportion of propionate was found at 6 h (p < 0.05). The protection rate of the RPAA prototypes ranged from 29.85 to 109.21%. at 24 h. In conclusion, the chemically synthesized RPAA prototypes studied here had no detrimental effects on rumen fermentation parameters. Further studies using animal models are needed for more accurate evaluations of the effectiveness of RPAA.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.957-967
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• 2016

The present study was conducted to investigate effect of dietary protected amino acid on milk yield and composition in dairy cow using meta-analysis. Total 21 research papers were employed in analysis, and mixed model was used for the analysis of effects. Effect of protected methionine (PM) and combination of protected methionine and lysine (PML) were investigated under two different levels of dietary crude protein (CP, <18% and >18%). For performance of dairy cow, milk yield, milk composition including milk fat and protein content and yield and 4% FCM (fat corrected milk) production were used for analysis. In case of milk yield, a trend of increment was found at PM supplementation at low CP (P=0.055). However, the effect of PM at high CP was detected as not significant (P>0.05). In case of milk protein, inclusion of PM at low CP showed significant decrement (P<0.05). However, there was no significant effect of MP on milk protein at high CP (P>0.05). Supplementation of MP at high CP level showed significant increment of milk fat (P<0.05). MP supplementation represented significant increment of 4% FCM production (P<0.05) regardless of dietary CP levels. Effects of PML on milk yield and composition at both of low and high dietary CP were not significant in this study. However, it seem to be that there was a possible positive effect of MPL application at high dietary CP on performance of dairy cow.

• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.376-379
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• 1991

Pyrazolone group containing resin was tested as an acyl carrier in solid phase peptide synthesis. Several kinds of dipeptide derivatives were prepared by aminolysis reactions of Boc-amino acid-pyrazolone resin active ester with various carboxyl protected amino acid derivatives. It was found that the rates of aminolysis reactions were largely dependent on the bulkiness of the amino acid side chains, the carboxyl protecting groups, and the swelling property of the resin. All the dipeptide derivatives were obtained in high yield in 20-30 minutes, and the pyrazolone resin could be reused repeatedly in peptide synthesis without any change of its reactivity.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.12
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• pp.1705-1711
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• 2014

The objective of this study was to evaluate the effect of ruminally protected amino acids (RPAAs) and ruminally protected fat (RPF) supplementation on ruminal fermentation characteristics (in vitro) and milk yield and milk composition (in vivo). Fourteen mid-lactating Holstein dairy cows (mean weight $653{\pm}62.59kg$) were divided into two groups according to mean milk yield and number of days of postpartum. The cows were then fed a basal diet during adaptation (2 wk) and experimental diets during the treatment period (6 wk). Dietary treatments were i) a basal diet (control) and ii) basal diet containing 50 g of RPAAs (lysine and methionine, 3:1 ratio) and 50 g of RPF. In rumen fermentation trail (in vitro), RPAAs and RPF supplementation had no influence on the ruminal pH, dry matter digestibility, total volatile fatty acid production and ammonia-N concentration. In feeding trial (in vivo), milk yield (p<0.001), 4% fat corrected milk (p<0.05), milk fat (p<0.05), milk protein (p<0.001), and milk urea nitrogen (p<0.05) were greater in cows fed RPAAs and RPF than the corresponding values in the control group. With an index against as 0%, the rates of decrease in milk yield and milk protein were lower in RPAAs and RPF treated diet than those of basal diet group (p<0.05). In conclusion, diet supplemented with RPAAs and RPF can improve milk yield and milk composition without negatively affecting ruminal functions in Holstein dairy cows at mid-lactating.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.309-313
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• 1996

This experiment was carried out to investigate the effect of rumen-protected lysine (RPLys) on growth rate, feed efficiency and plasma amino acid concentrations in sheep. RPLys was supplemented at the level of 0% ($T_1$), 0.2% ($T_2$) and 0.4% ($T_3$) of total DMI with 24 sheep in a 56 day feeding trial. The results are summarized as follows: 1. live weight gain of sheep in groups $T_1$, $T_2$ and $T_3$ was 219, 216 and 244 g/d, and was significantly (p < 0.05) higher for $T_3$ through the entire experiment. 2. Feed intake was not affected by RPLys supplementation. 3. The group fed $T_3$ had a significantly (p < 0.05) better feed efficiency than the groups fed $T_1$ and $T_3$. The response of $T_3$ was higher in growing period II of feeding low protein basal diet than in period I. 4. Plasma lysine concentrations tended to be higher with supplementing RPLys, but there were no differences between $T_2$ and $T_3$. 5. Supplementing RPLys in the diets increased plasma concentrations of arginine, asparagines, threonine, serine, valine and leucine compared with sheep receiving no RPLys. In contrast, plasma histidine was lower in sheep fed the supplementing RPLys than fed the diet $T_1$ with significant (p < 0.05) difference.