• Applied Biological Chemistry
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• v.30 no.4
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• pp.305-310
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• 1987

The enzymatic properties of ${\beta}-amylase$ from soybean and sweet potato were compared. The sweet potato enzyme consists of four identical subsunits whereas soybean enzyme has no subunit $structure^{12,\;15)}$. In the denatured state, both enzymes exhibited the same molecular weight on SDS-gel electrophoresis and on gel-filtration analysis. The spectra of circular dichroism revealed that both enzyme have almost same secondary structure but the environment of aromatic side chains are different. The chemical cleavage of soybean and sweet potato ${\beta}-amylases$ at cysteine residues and methionine residues demonstrated the homology of amino acid sequence between the enzymes. The similarity between soybean and sweet potato ${\beta}-amylase$ was also revealed by immunological method. The antibody for soybean enzyme inhibited the activity of sweet potato enzyme but it did not inhibit the activity of wheat, barley and Japanese-raddish ${\beta}-amylases$.

• The Korean Journal of Food And Nutrition
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• v.9 no.3
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• pp.247-252
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• 1996

$\beta$-Amylase was purified from sweet potato by acetone fractlonatlon, Sephadex A-50 ion exchange chromatography and Sepgadex G-200 gel chromatographyl The higher enzyme concentration was, the higher heat stability of enzyme became. After 1 hour 30 minute. At 6$0^{\circ}C$ in pH 5, enzyme under concentration of 30$\mu$l/ml lost its activity completely and over the concentration of 100$\mu$g/ml remained 25% of activity. The enzyme was stabilized at range of pH 4~10 and pH stability was increased by glycerol. Five moles of NaCl inhibited completely of the enzyme activity. SDS of 0.05% inhibited the enzyme completely after 12 hours at 37$^{\circ}C$ in pH5. One mole guanidine-HCl and 8M urea inhibited the entire enzyme after 13 hours at 37$^{\circ}C$ in pH 5.

• The Korean Journal of Food And Nutrition
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• v.9 no.3
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• pp.253-258
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• 1996

Stabilities of sweets potato f-amylase on various reagents were studied. The enzyme was stabilized by bovine serum albumin, Triton X-100 and 2-mercaptoethanol of 0.04%. Among them, bovine serum albumin was the most effective. And enzyme stability was increased by using the deairated solution. The enzyme activity was remained 0% in the absence of glycerol, 25% in the presence of 20% glycerol and 50% in the presence of 40% glycerol at 37$^{\circ}C$, for 15 hours in pH 11. SDS inhibited the enzyme, and 2-mercaptoethanol and dithiothreitol stabilized it.

• The Korean Journal of Food And Nutrition
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• v.11 no.5
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• pp.561-564
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• 1998

The stabilizatio of amaylolytic enzyme such as $\beta$-amylase of barley, $\beta$-amylase of wheat, $\beta$-amylase of sweet potato, $\alpha$-amylase of Bacillus licheniformis, $\alpha$-amylase of Aspergillus sp. and $\alpha$-glucosidase of Aspergillus awamori was attained by modification with periodate-oxidized soluble starch. The pH stability of modified enzyme was increased at pH 9 for $\beta$-amylase of sweet potato, pH 3~5 and 8~11 for $\beta$-amylase of barley, pH 2~3 and 7~12 for $\beta$-amylase of wheat and pH 6 for $\alpha$-glucosidase of Aspergillus awamori. Thermal stability increased 17.6% for $\alpha$-amylase of Aspergillus sp. at 6$0^{\circ}C$ for 10min, 30% for $\alpha$-amylase of Bacillus licheniformis at 10$0^{\circ}C$ for 5min and 4.5% for $\alpha$-amylase of sweet potato at 6$0^{\circ}C$ for 10min compared with those of native enzymes.

• Korean journal of food and cookery science
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• v.14 no.2
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• pp.182-187
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• 1998

The changes in weight, reducing sugar content, sugar composition and enzyme activities (${\beta}$-amylase and invertase) of sweet potato were studied with three kinds of cooking methods, microwave oven, gas oven, and steaming. The weights of sweet potato cooked by microwave oven and gas oven were decreased with increasing cooking time, whereas that of steaming was increased with cooking time. Reducing sugar content of sweet potato cooked by microwave oven was increased till 40 seconds, but decreased thereafter. In the cooking methods using gas oven and steaming, reducing sugar content were increased with cooking time. And reducing sugar content were 334.60 mg/g and 381.29 mg/g, respectively at 100$^{\circ}C$ of cold point in sweet potato cooked by gas oven and steaming. Raw sweet potato consisted of fructose (1.56 mg/g), glucose (1.79 mg/g), sucrose (5.58 mg/g), and maltose (2.22 mg/g). The contents of fructose, glucose, and sucrose were decreased during cooking process. But maltose content was increased with cooking time. Especially, maltose contents were 24.81 mg/g and 28.10 mg/g at 100$^{\circ}C$ of cold point in sweet potato cooked by gas oven and steaming. The activities of ${\beta}$-amylase and invertase were decreased with cooking time. Microwave oven-cooked sweet potato did not show on invertase activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.943-947
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• 1995

The sweet potato drinks were prepared with the reaction of sweet potato and complex enzyme(${\beta}-amylase,\;{\alpha}-amylase$, protease). The reducing sugar and soluble solid of sweet potato drinks were the highest on reaction of sweet potato : water(1 : 1) and complex enzyme(pH 4.5). In the color of the sweet potato drinks, hunter value(L, a, b) were the lowest on reaciton of sweet potato : water(1 : 1) and complex enzyme, and were the highest on reaciton of sweet potato : water(1 : 3) and complex enzyme(pH 4.5). In the sensory test of the sweet potato drinks, the sensory score(color, taste, flavor, texture) were the best on reaction of sweet potato : water(1 : 1) and complex enzyme(pH 4.5). These results demonstrated that the sweet potato drink was good to drink when sweet potato : water(1 : 1) were treated with complex enzyme at pH 4.5, $60^{\circ}C$ for 5 hrs.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.62-67
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• 1999

Periodate-oxidized soluble starch and maltohexaose, maltotetraose, maltose, and glyceraldehyde reacted with sweet potato ${\beta}-amylase$, wheat ${\beta}-amylase$, aldolase, bovine serum albumin, catalase, carboxypeptidase, ferritin and pronase. Electrophoretical mobility of modified proteins was different from that of native proteins, and modified proteins were stained with periodic acid-Schiff while native proteins did not stain. This results means that oxidized sugars attached on proteins. This bond is based on the Schiffs base between CHO group of oxidized sugar and ${\varepsilon}-NH_2$ group of lysine of protein. There is no changed UV absorption spectrum of sweet potato ${\beta}-amylase$ modified with oxidized soluble starch, in comparison with native enzyme.

• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.159-164
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• 1998

pH stability of sweet potato $\beta$-amylase modified with IO4-oxidized soluble starch was increased at pH 3, 5~9 and 11. And optimum pH was 3 and 5 for modification. Thermal stability of the enzyme modified with IO4-oxidized soluble starch was increased at 6$0^{\circ}C$ for 15 min. pH stability of barley $\beta$-amylase modified with IO4-oxidized soluble starch was increased at 3~4 and 8~11, and more increased at pH 3 and 8~11 in the presence of $\alpha$-cyclodextrin.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.431-436
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• 1986

The action of crude amylolytic enzymes extracted from Wonki and Chunmi sweet potatoes, ${\alpha}-amylase$, and ${\beta}-amylase$ on the sweet potato starches from Wonki (dry type) and Chunmi (moist type) were studied. The activity of crude amylolytic enzyme extracted from Wonki was higher than that extracted from Chunmi. The content of reducing sugar released from the reaction between crude amylolytic enzyme and Chunmi starch preheated at $70^{\circ}C$ was higher, but that preheated at $95^{\circ}C$ was lower than that from Wonki starch preheated at the same temperature. The activites of ${\alpha}-amylase$ and ${\beta}-amylase$ on the Wonki starch were higher than those of the Chunmi starch at the same conditions. Iodine affinity of amylolytic enzyme-treated starch was decreased and enzyme treated starch granule shape was found with porous structure having inner layers. X-ray diffraction patterns of amylolytic enzyme-treated starches were the Ca type like the intact starches and relative crystallinity was decreased.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.482-487
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• 1999

Periodate-oxidized soluble starch and maltohexaose reacted with ${\alpha}-NH_2$ group of free amino acids and ${\varepsilon}-NH_2$ group of peptidyl lysine. The result shows that periodate-oxidized soluble starch and maltooligosaccharides reacted with protein and formed Schiff base between CHO group of oxidized sugar and ${\varepsilon}-NH_2$ group of surface lysine of protein molecule. Carbon and hydrogen composition of sweet potato ${\beta}-amylase$ modified with oxidized soluble starch increased and it's nitrogen composition decreased. Carbohydrate contents of sweet potato ${\beta}-amylase$ modified with oxidized soluble starch were 13.2% (pentamer), 13.4% (monomer), and with oxidized maltohexaose were 9.7% (pentamer), 9.3% (monomer) by $phenol-H_2SO_4$ method. Alpha-amino group of N-terminal, and ${\varepsilon}-NH_2$ group of lysine, of sweet potato ${\beta}-amylase$ were reacted with oxidized soluble starch by dinitrophenylation were 70% (pentamer), 73% (monomer) and 33% (pentamer), 26% (monomer), respectively, in comparison with native enzyme.