• 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.

• The Korean Journal of Food And Nutrition
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• v.18 no.1
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• pp.4-10
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• 2005

Periodate-oxidized soluble starch increased pH stability of Aspergillus awamori a-glucosidase. After incubation for two hours, the enzyme in the absence of oxidized soluble starch was stable in the range of pH 3-7 at 40℃, pH 3-6 at 50℃ and the enzyme in the presence of oxidized soluble starch was stable in the range of pH 3-9 at 40℃, pH 3-8 at 50℃. At 60℃, the enzyme was stable in pH 3-6 regardless of the presence or absence of IO₄-oxidized soluble starch, but when IO₄-oxidized soluble starch existed in pH 5-6, remained activity of the enzyme increased 20% more than when it didn't exist. The enzyme modified with IO₄-oxidized soluble starch remained 70% of activity in pH 9, but native enzyme didn't remain, showing the increase of stability due to modification. In thermal stability, modified enzyme remained 12% at 50℃ and 7% at 80℃. But native enzyme remained 8% at 50℃ and didn't remain at more than 70℃. The result of HPLC analysis revealed the subunit of the enzyme at under pH 2 or over pH 9 was separated or the enzyme was denatured and conjugated. Protein structure of native enzyme was denatured by acidic and basic pH but was stable in the presence of IO₄-oxidized soluble starch.

• 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.

• The Korean Journal of Food And Nutrition
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• v.12 no.3
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• pp.265-270
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• 1999

The stabilization of Aspergillus sp. $\alpha$-amylase was attained by modification with periodate-oxidized sol-uble starch. The pH stability of modified enzyme was increased at pH 3~4 and 9~11 in the presence of $\alpha$-cyclodextrin($\alpha$-CD) compared with that of native enzyme. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 30min the activity remained 20% for the enzyme modified at pH 9.7 in the presence of $\alpha$-CD and tested in the presence of $\alpha$-CD 10% for the enzyme modified at pH 9.7 in the presence of $\alpha$-CD 0% for the native enzyme. The native enzyme and modified enzyme showed one peak in HPLC. The substrate specificity of the modified enzyme was not changed in HPLC analysis of reaction product.

• The Korean Journal of Food And Nutrition
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• v.20 no.4
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• pp.349-355
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• 2007

Periodate-oxidized soluble starch was reacted with papain at pH 4.0, pH 7.0, and pH 9.7, and an oxidized soluble starch-papain conjugate was produced. When compared with native papain, the specific activity decreased to 60%, in both the modified papain reacted with 0.4% $NaBH_4$ and in the modified papain not reacted with $NaBH_4$. The specific activity decreased to 70% in the modified papains reacted with 1.5% $NaBH_4$ and 4.0% $NaBH_4$, respectively. The reduction by $NaBH_4$ did not have an effect in the thermal stability of either the modified or nonmodified papain. An activity of 54.7% remained in the papain modified at pH 4.0, which was incubated at $80^{\circ}C$ for 40 min. The papains modified at pH 7.0 and pH 9.7 and incubated for 40 min at two different temperatures, respectively, were stable to $60^{\circ}C$, and at $80^{\circ}C$ their activities at 56.3% and 44.1 %, respectively. The modified papain's thermal stability pattern was similar to that of native papain, with no increase in its statbility. In the range of pH $2.0{\sim}13.0$, the stability of the papain modified at pH 4.0 decreased greatly between pH $3.0{\sim}5.0$, but it was similar to the native papain at other pH values. The stability of the papain modified at pH 7.0 showed a similar pattern to the native papain at pH $2.0{\sim}6.0$, while its stability increased when moving into the alkali pH range. The papain modified at pH 9.7 also had increased stability, when moving into the alkali range. The results of Hammerstein milk casein, which was reacted with the papains modified at pH 4.0, pH 7.0, and pH 9.7, respectively, and analyzed by FPLC, showed different peaks according to the different modification pHs, and the greatest peak differences were observed with the modification at pH 9.7.

• The Korean Journal of Food And Nutrition
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• v.13 no.4
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• pp.342-347
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• 2000

The stabilization of barley $\beta$-amylase(Biozyme ML, Amano) was attained by modification with periodate-oxidized soluble starch. The specific activities of modified enzyme at pH 9.7 and pH 8.0 were 42% and 92%, respectively, compared with that of native enzyme. The pH stability of modified enzyme was increased at pH 2~5 and 7~12 in the presence of $\alpha$-cyclodextrin( $\alpha$ -CD) compared wish that of native enzyme. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 10min. the activity remained 8% for the enzyme modified at pH 8.0 in the presence of $\alpha$-CD, 4.5% for the native enzyme. The native enzyme and modified enzyme showed two peak in HPLC. The molecular weight of the modified enzyme was slightly increased in HPLC analysis.

• The Korean Journal of Food And Nutrition
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• v.14 no.3
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• pp.263-268
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• 2001

NaIO$_4$-산화 전분당을 Bacillus licheniformis의 $\alpha$-아밀라아제의 반응시켜서 시프염기 형성으로 당단백질로 변형시켜서 안정성을 확인하였다. 10$0^{\circ}C$에서의 열안정성은 10분 뒤에, pH 9.7에서 변형한 효소 비변형 효소의 순으로 높았다. 그러나 변형 및 안정성에 $\alpha$-cyclodextrin($\alpha$-CD)을 사용한 결과 큰 차이는 나지 않았다. pH 8.0에서 $\alpha$-CD 존재하에 변형한 효소는 pH 8~11dml 알칼리쪽에서 가장 높은 안정성을 나타냈으나, pH 5~7사이에는 다른 효소보다 낮았다. pH 9.7에서 변형하지 않은 효소는 pH 5부터 pH 13까지 서서히 증가하였고 pH 9.7에서 $\alpha$-CD존재 하의 효소는 pH 5부터 7까지 증가하다가 그 후 pH13까지 서서히 감소하였다. $\alpha$-CD존재하의 비변형 효소는 pH 7과 10에서 피크를나타낸 다음 pH12이후에는 급격히 낮아졌다. 변형한 효소는 HPLC 의 유출시간이 빨라wu서 변형하지 않은 효소보다 분자량이 큰 것으로 나타났다. 분자량 크기는 비변형 효소

• The Korean Journal of Food And Nutrition
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• v.13 no.4
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• pp.348-352
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• 2000

The stabilization of wheat $\beta$-amylase( Himaltosin GL, Hankyu-Bio) was attained by modification wish periodate-oxidized soluble starch. The specific activities of modified enzyme at pH 9.7 and pH 8.0 were 17% and 96%, respectively, compared with that of native enzyme. The pH stability of modified enzyme was increased at pH 2~5 and 6~12 in the presence of $\alpha$-cyclodextrin( $\alpha$-CD) compared with that of native enzyme, and optimum pH of the enzyme was changed from pH 5.0 to pH 7.0 by the modification. Thermal stability of the modified enzyme was increased. After treatment at 6$0^{\circ}C$ for 10min, the activity remained 8% for the enzyme modified at pH 8.0 in the presence of $\alpha$-CD and tested in the presence of $\alpha$-CD, 5% for the native enzyme. The native enzyme and modified enzyme showed one peak in HPLC. The molecular weight of the modified enzyme was slightly increased in HPLC analysis.