• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.217-221
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• 2002

dTDP-D-glucose 4,6-dehydratase (TDPDH) catalyzes the conversion of dTDP-D-glucose to dTDP-4-keto-6-deoxy-D-glucose, and requires $NAD^＋$ as a coenzyme for its catalytic activity. The dTDP-D-glucose 4,6-dehydratase from Streptomyces antibioticus $Tu{\ddot}99$ tightly binds $NAD^＋$ [19]. In order to determine the role of lysine-148 in the $NAD^＋$ binding, the lysine of the dTDP-D-glucose 4,6-dehydratase from Streptomyces antibioticus $Tu{\ddot}99$ was mutated to various amino acids by site-directed mutagenesis. The catalytic activity of the four mutated enzymes of TDPDH did not recover after addition of $NAD^＋$ . However, the activity of K159A, the mutated enzyme of UDP-D-glucose 4-epimerase (UDPE), recovered after the addition of $NAD^＋$ [15]. Although dTDP-glucose 4,6-dehydratase, and UDP-galactose (glucose) 4-epimerase are members of the short-chain dehydrogenase/reductase SDR family and the lysine-148 of TDPDH was highly conserved as in UDPE (Lys-159), the function of the lysine-148 of TDPDH was different from that of UDPE. The mutated enzymes showed that the lysine-148 of the dTDP-D-glucose 4,6-dehydratase played no role in the $NAD^＋$ binding. Accordingly, it is suggested that the lysine-148 of the dTDP-D-glucose 4,6-dehydratase is involved in the folding of TDPDH.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.1045-1051
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• 1997

Three kinds of model melanoidins adjusted to have the same brown color intensity were made from glucose-glycine, glucose-lysine, xylose-arginine and their antioxidative properties were determined. The antioxidative activities of these model melanoidins in linoleic acid emulsion system were determined by ferric thiocyanate method, conjugated diene contents, peroxide value and electron donating ability by DPPH. Xylose-arginine melanoidin showed the strongest antioxidative activity and electron donating ability. The antioxidative effect of melanoidin could be reliably predicted by determining peroxide value and DPPH method. Each melanoidin was separated on Sephadex G-50 column, and brown color intensity, reducing power, ninhydrin positive reaction and antioxidative activity of each fraction were determined. The antioxidative activities of melanoidin fractions showed strong correlation with their brown color intensity and especially to their reducing power. In spite of same brown color intensity, there is no big differences between these model melanoidins, thus xylose-arginine showing strongest antioxidative activity followed by glucose-lysine and glucose-glycine melanoidin. Xylose-arginine melanoidin also showed the strongest electron donating activity and broad range of reducing power when fractionated on Sephadex G-50, which was different tendency from the other model melanoidin.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.10-15
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• 1996

To determine the quality of heated protein, in vitro method, invluding lysine, lysionalanine, and fructose-lysine as well as homoarginine by guanidination of lysine, was assessed using heated casein with of without glucose. In vivo methods such as PER, digestibility and BV were also tried on homoarginine, lysinoalanine, fructoselysine, and lysine. The nonreactive lysine for huanidination was hardly digestive, while the non heat damaged lysine side chanis in the protein were accessible for guanidination as well as for the digestion. A linear correlation(${\gamma}$=0.80) was obstained between PER and digestibility of the analysed lysine. Digestibility of homoarginine was higher that of true protein. However, in the guanidinated heated casein with glucose, digestibility of homoarginine was significantly reduced. It is suggested that the homoarginine method may mislead to over- or underestimation of the damaged protein quality.

• The Korean Journal of Zoology
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• v.11 no.3
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• pp.75-82
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• 1968

The effects of x-irradiation on the utilization of glucose, succinate, citrate and $\\alpha$-ketoglutarate, on the response of the cell metabolism to $NaN_3$ and DNP, and on the uptake of lysine in the presence or absence of the metabolitesor the inhibitors were studied using HeLa cells and the results are summarized as follows: 1. 200r of x-irradiation had no immediate effect on the oxygen consumption of cells. 2. The oxygen consumption was greatly stimulated by succinate, $\\alpha$-ketoglutarate and citraed and in decreasing order and x-irradiation caused no remarkable change in this order. 3. The respiratory response of the cell to the metabolic inhibitors seems to be altered by x-irradiation. 4. The initial rate of the uptake of lysine was markedly retarded and the accumulation of lysine in the cell was decreased by irradiation. 5. Glucose increased the lysine uptake whereas succinate had no effect and citrate and $\\alpha$-ketoglutarate reduced the absorption. X-irradiation did not alter this tendency. 6. The inhibitory effects of $NaN_3$ and DNP on the lysine uptake were quite different from those seen in the oxygen consumption.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.853-859
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• 2017

This study was conducted in an effort to investigate the effect of Maillard reaction products (MRPs) on enzymatic browning of burdock and their anti-oxidant activity. The MRPs were prepared by heating glucose and amino acids at $90^{\circ}C$, which served to produce a strong inhibitory effect on burdock polyphenol oxidase. As the reaction time of the solution containing glucose and amino acid increased at $90^{\circ}C$, the production of MRPs increased and intensity of the brown color deepened. When MRPs were prepared by heating at $90^{\circ}C$ for five hours, the absorbance of MRPs from glucose and lysine was 6.44, while those of glucose and glycine was 1.95. The MRPs synthesized from the glucose and lysine also reduced the pH of MRPs from 5.60 to 4.51, but those from glucose and glycine decreased slightly from 5.57 to 5.33. The Michealis-Menten constant value ($K_m$) of burdock PPO with pyrocatechol as a substrate was 16.0 mM, and MRPs were a non-competitive inhibitor against burdock PPO. The anti-oxidant activity of MRPs was measured by evaluating its radical scavenging activities of DPPH radicals, ABTS radicals and reducing power. The color intensity of MRPs produced by lysine and glucose were deeper than that produced by glucose and glycine. It was also found that MRPs produced from glucose and lysine exhibited stronger anti-oxidant properties than those produced by glucose and glycine.

• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1368-1376
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• 2014

This article focuses on the effects of glycine betaine on preventing caramelization, and increasing DCW and $\small{L}$-lysine production. The additional glycine betaine not only decreased the browning intensity (decreased 4 times), and the concentrations of 5-hydroxymethylfurfural (decreased 7.8 times) and furfural (decreased 12 times), but also increased the availability of glucose (increased 17.5%) for $\small{L}$-lysine production. The DCW and $\small{L}$-lysine production were increased by adding no more than 20 mM glycine betaine, whereas the DCW and $\small{L}$-lysine production were decreased with the reduction of pH values, although pH had a better response to prevent caramelization than did glycine betaine. For $\small{L}$-lysine production, the highest increase (40%) was observed on the media with 20 mM glycine betaine. The crucial enzymes in glycolysis and $\small{L}$-lysine biosynthesis pathway were investigated. The results indicated that additional glycine betaine increases the activity of enzymes in glycolysis, in contrast to the effect of pH. All the results indicated that glycine betaine can be used to prevent caramelization and increase the $\small{L}$-lysine production. By applying this strategy, glucose would not be have to be separated from the culture media during autoclaving so that factories can save production costs and shorten the fermentation period.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1297-1304
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• 2007

We conducted a series of investigations in order to elucidate role of nutritional status in regulating GLUT expression and energy metabolism in porcine muscle. Firstly, the role of mild undernutrition in regulating muscle GLUT gene expression and function was studied in growing pigs (3 wk of age) on a high (H) or low (L) food intake (H = 2L) at $35^{\circ}C$ or $26^{\circ}C$. Low food intake selectively upregulates GLUT1 and GLUT4 gene expression; mRNA levels were elevated in longissimus dorsi (L. dorsi) and rhomboideus muscles but not in diaphragm or cardiac muscles. Our next step was to determine whether dietary lysine, a major primary limiting amino acid in diets for pigs, affects muscle GLUT4 expression. Pigs of 6 wk of age were pair-fed a control or low lysine (LL) diet. The control diet contained optimal amounts of all essential amino acids, including 1.15% lysine. The LL diet was similar but contained only 0.70% lysine. GLUT4 mRNA expression was upregulated by the LL diet in L. dorsi and rhomboideus muscles, whereas that in cardiac muscle was unaffected. GLUT4 protein abundance was also higher in rhomboideus muscle of animals on the LL diet. We conducted another investigation in order to elucidate effects of the LL diet on post-GLUT4 glucose metabolism. Activity of hexokinase was unaffected by dietary lysine levels while that of citrate synthase was higher both in L. dorsi and rhomboideus muscles of pigs fed on the LL diet. Glucose 6-phosphate content was higher in L. dorsi msucle in the LL group. Glycogen content was higher both in L. dorsi and rhomboideus muscles in the LL group. Further, we determined the effects of dietary lysine levels on accumulation of intramuscular fat (IMF) in L. dorsi muscle of finishing pigs. A low lysine diet (lysine content was 0.40%) meeting approximately 70% of the requirement of lysine was given to finishing pigs for two months. IMF contents in L. dorsi of the pigs given the low lysine diet were twice higher than those of the pigs fed on a control diet (lysine content was 0.65%). Finally, we proved that a well known effect of breadcrumbs feeding to enhance IMF of finishing pigs could be attributed to shortage of amino acids in diets including breadcrumbs.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1440-1446
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• 1999

Fourty-two commercial vinegars were analyzed for their non-volatile organic acids, free sugars. amino acids, and volatile compounds. A study was made to characterize commercial vinegars chemically into three kinds of vinegars such as spirit, cider, and brown rice vinegars. Sixteen chemical components were significantly effective for the chemical characterization of commercial vinegars by stepwise discriminant analysis. Those were malic, succinic and lactic acids from the non-volatile organic acids; fructose and glucose from the free sugars; lysine, serine, leucine, valine and alanine from the amino acids; 1-hexanol, acetaldehyde, 3-methyl-1-butanol, 2-methylpropanoic acid, isopropyl butanoate and ethanol from the volatile compounds. Six components including malic acid, lysine, succinic acid, glucose, lactic acid and 1-hexanol were the most significant contributors to the differentiation of commercial vinegars into spirit, cider, and brown rice vinegars. In particular, cider vinegars could be characterized to be abundant in amounts of malic acid and 1-hexanol, whereas brown rice vinegars in amounts of lysine and lactic acid compared to spirit vinegars.

• Food Science of Animal Resources
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• v.29 no.4
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• pp.487-493
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• 2009

This study was conducted to investigate the effect of various combinations of sugars, amino acids, and fatty acids (oleic/linoleic aicds) on volatile compounds of low-fat sausages (LFSs) to have similar characteristics to those with regular-fat counterparts (RFC). The addition of glucose or fructose alone in LFC increased the concentrations of myristicine, pentadecanal and octadecanal, as compared to RFC. In addition, LFSs containing lysine alone had higher concentration of myristicine, as compared to those with RFC. Without the addition of both oleic and linoleic acids, LFS containing glucose in combination with various amino acids, such as alanine, aspartic acid, cysteine, and lysine, had higher concentration of myristicine, as compared to RFC. Furthermore, myristicine content (ppm) of LFSs was different from those of RFC, regardless of the concentration of lysine in combined with glucose or fructose. LFSs containing oleic and linoleic acids with the combination of glucose/glycine or glucose/alanine had the most similar volatile compounds to those of RFC. These results indicated that volatile compounds isolated from smoked LFSs containing sodium caseinate as a fat replacer and the multiple combinations of sugar, amino acids, and fatty acids had the most similar volatile compounds to those of RFC.

• Journal of Nutrition and Health
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• v.21 no.4
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• pp.197-212
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• 1988

To study the effect of preventing the browning reaction between casein and glucose by protecting the reactants using corn starch with coating material, rats were fed for 30 days nonbrowning diet, nonprotected browning diet, browning diet protected only casein, browning diet protected both casein and glucose and browning diet supplement sucrose simultaneously with protecting both casein and glucose. The amounts of fructosyl-lysine excreted through urine were greater than those through feces regardless of diets and the both side of the excreted amounts of fructosly-lysine through urine or feces were greater for rats fed browning diets regardless protecting compared to rats fed the nonbrowning diet. Through urine, the excreted amounts of fructosyl-lysine were decreased for rats fed the browning diet supplemented sucrose simultaneously with protecting both casein and glucose than those for rats fed the nonprotected browning diet and through feces, were decreased for rats fed protected browning diets regardless of protecting method than the nonprotected browning diet. The excreted amounts of all individual essential free amino acids through feces were increased for rats fed browning diets irrespective of protecting compared to the nonbrowning diet, but through urine, were increased or similar level for rate fed the nonbrowning diet compared to browning diets except histidine. The excreted amount of free lysine through feces were decreased for rats fed protected browning diets than nonprotected browning diet. Fructosyl-lysine contents of serum, liver and small intestinal digesta were increased for rats fed browning diets regardless of protecting by starch compared to nonbrowning diet but, of serum and small intestinal digesta were decreased for rats fed protected browning diets than the nonprotected browning diet.