• Title/Summary/Keyword: modified protein

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The Physicochemical Properties of Modified Soybean Protein Isolate by Dimethylglutarylation (Dimethylglutarylation에 의한 변형대두단백질의 물리화학적 특성)

  • Choi, One-Kyun;Jung, Chul-Won
    • Journal of the Korean Society of Food Culture
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    • v.14 no.5
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    • pp.467-476
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    • 1999
  • We studied to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Soybean protein isolate was acylated rapidly up to 80% modification and more of 80% modification was proceed slowly. Electrophoretic analysis showed that more changes in modified protein. Also, modification of soybean protein produced more ionizable tyrosines and exposed more hydrophobic groups, while modified protein exhibited a loss of reactive sulfhydryl groups. Spectrophoretic studies demonstrated that the shift was occurred at the UV 278nm and fluorescence 333nm, respectively, and the intensity decreased as the degree of modification was increased.

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Free Radicals during the Oxidation and Reduction of Methylglyoxal-Modified Protein

  • Lee, Cheolju;Kang, Sa-Ouk
    • Proceedings of the Korean Biophysical Society Conference
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    • 1997.07a
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    • pp.36-36
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    • 1997
  • Protein glycation was studied with bovine serum albumin (BSA) as a model protein and methylglyoxal, a 3-carbon ${\alpha}$-ketoaldehyde. Methylglyoxal reacted with BSA, forming a radical as observed in the reaction of methylglyoxal wtih L-alanine or N-acetyl-L-lysine.(omitted)

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Effect of Proteins Modified by Enzymically Oxidized Caffeic Acid on the Concentration of Serum Cholesterol of Rats (효소적 갈변 단백질이 흰쥐 혈청콜레스테롤 농도에 미치는 영향)

  • Cho, Young-Su
    • Applied Biological Chemistry
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    • v.37 no.5
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    • pp.379-384
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    • 1994
  • Casein or soybean protein was subjected to the reaction with caffeic acid-tyrosinase system at $30{\sim}35^{\circ}C$ pH 6.8 with aeration for 5 hr. The effects of the modified proteins on male Wistar rats were studied by pair-feeding of a cholesterol-free diet for 2 weeks. Significant decrease in protein digestibility for the rats fed with the modified proteins was observed. The feeding of modified protein from casein caused an enlargement of caecum. The concentration of serum cholesterol and triglyceride in the rats fed with modified proteins were mostly unchanged against the rats fed with untreated proteins. These results suggest that the decrease in protein digestibility induced by enzymic browning-reaction did not cause the decrease in concentration of serum cholesterol.

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Development of new food protein through chemical modification of rice bran proteins

  • Bae, Dongho;Jang, In Sook
    • Journal of Applied Biological Chemistry
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    • v.42 no.4
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    • pp.180-185
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    • 1999
  • Protein concentrate was produced and succinylated from rice bran to assess and improve its functional properties for the purpose of expanding the uses of rice bran proteins. The most effective solvent for the extraction of rice bran proteins was 20% aqueous ethanol at pH 9. The protein content of rice bran protein concentrate produced was 70.0% and the total protein yield was 64.3%. The extent of succinylation of free amino groups in the modified products was 72.8%. Though the modified protein products showed good functional properties including solubility, emulsion properties, and oil absorption capacity, it did not form gel. Succinylation improved solubility and emulsion and gelling properties. These improvements in functionality will enhance the value of rice bran proteins, thus enabling them to be more competitive with other food proteins.

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Effects of proteins modified by enzymically oxidized caffic acid on yhe concentration of serum cholestrol of rats, part II (효소적 갈변 반응에 의하여 생성된 갈변 물질이 휜쥐 혈청콜레스테롤 농도에 미치는 영향)

  • 조영수;정순재
    • Journal of Life Science
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    • v.5 no.2
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    • pp.57-62
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    • 1995
  • Casein or soybean protein was subjected to there action with caffeic acidtyrosinase system at 30-35$\circ$C, pH 6.8 with aeration for 5hr. The resulting brown proteins were washed with acetone until the washings were on longer colored. However, modified protein still retained a light brown. The effects of the modified proteins and brown compounds on male Wistar strain rats were studied by pair-feeding of a cholesterol-free diet for 14days. Significant decrease in protein digestibility for the rats fed with the modified proteins were observed. Weight gain and protein digestibility were not influenced by feeding brown compounds, but the feeding of brown compound from casein caused an enlargement of caecum. The concentrations of serum cholesterol and triglyceride in the rats fed with modified proteins and brown compounds were mostly unchanged against the rats fed with untreated proteins. These results suggest that the decrease in protein digestibility induced by enzymic browning-reaction did not cause the decrease in concentration of serum cholesterol.

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Effects of proteins modified by enzymically oxidized caffic acid on yhe concentration of serum cholestrol of rats, part II (효소적 갈변 반응에 의하여 생성된 갈변 물질이 휜쥐 혈청콜레스테롤 농도에 미치는 영향)

  • Jo, Young-Su;Jeong, Soon-Jae
    • Journal of Life Science
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    • v.5 no.2
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    • pp.1-1
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    • 1995
  • Casein or soybean protein was subjected to there action with caffeic acidtyrosinase system at 30-35$\circ$C, pH 6.8 with aeration for 5hr. The resulting brown proteins were washed with acetone until the washings were on longer colored. However, modified protein still retained a light brown. The effects of the modified proteins and brown compounds on male Wistar strain rats were studied by pair-feeding of a cholesterol-free diet for 14days. Significant decrease in protein digestibility for the rats fed with the modified proteins were observed. Weight gain and protein digestibility were not influenced by feeding brown compounds, but the feeding of brown compound from casein caused an enlargement of caecum. The concentrations of serum cholesterol and triglyceride in the rats fed with modified proteins and brown compounds were mostly unchanged against the rats fed with untreated proteins. These results suggest that the decrease in protein digestibility induced by enzymic browning-reaction did not cause the decrease in concentration of serum cholesterol.

Rapid Preparation of Truncated Transaminases using a PCR-based Cell-free Protein Synthesis System (PCR 기반의 무세포 단백질 발현 시스템을 이용한 절단 트랜스아미나제의 고속생산)

  • Kwon, Yong-Chan;Park, Kyung-Moon;Kim, Dong-Myung
    • KSBB Journal
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    • v.21 no.4
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    • pp.302-305
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    • 2006
  • In this work, we attempted the application of cell-free protein synthesis technology for the rapid generation of truncated enzymes. Truncated DNAs of a transaminase were PCR-amplified and directly expressed in cell-free protein synthesis reactions. Variants of the transaminase were rapidly prepared and analyzed for their enzymatic activity. Described method that combines the PCR and cell-free protein synthesis technologies will offer a versatile platform for the rapid generation of optimally modified protein species.

Studies on the Preparation of Food Proteins from Castor Bean Protein (피마자 단백질의 식품화를 위한 연구)

  • Yoon, Joo-Ok
    • Korean Journal of Food Science and Technology
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    • v.12 no.4
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    • pp.263-271
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    • 1980
  • Detoxified and deallergenized castor bean protein isolate was prepared from defatted castor bean pomace for use in animal feedstuffs and human foods. Succinylation and acetylation of the ${\varepsilon}-amino$ groups of the protein improved markedly the water solubility of the protein at $pH\;7{\sim}8$. The results of the amino acid analysis of the protein isolate revealed that the sulfur-containing amino acids and L-lysine were limiting amino acids and that succinylation and acetylation caused some little loss of the amino acid content. The L-methionine enriched plastein was synthesized from the protein isolate or the acylated protein isolates and DL-methionine ethyl ester by one step process with papain. By this method the extent of incorporation of L-methionine was about 50%. Pepsin hydrolyzed both unmodified and modified protein isolates at the same rate (about 92%). Tryptic hydrolysis, however, was less for the succinylated protein isolates (about 42%) and less for the acetylated protein isolates (about 26%). The protein efficiency ratio of L-methionine enriched protein isolate (about 2.5 weight %) was 90% that of reference casein. The protein efficiency ratio values of succinylated (88%) and acetylated (84%) protein isolate were 55 and 69% of reference casein, respectively.

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Cloning and Functional Studies of Pro-Apoptotic MCL-1ES BH3M (세포사멸을 유도하는 새로운 단백질인 MCL-1ES BH3M의 클로닝 및 기능연구)

  • Kim, Jae-Hong;Park, Mira;Ha, Hye-Jeong;Lee, Kangseok;Bae, Jeehyeon
    • Development and Reproduction
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    • v.12 no.3
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    • pp.297-303
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    • 2008
  • BCL-2 family members are essential protein for the regulation of cell death and survival consisting both antiapoptotic and pro-apoptotic proteins. In the present study, we designed and cloned a new apoptotic molecule MCL-1ES BH3M coding a modified protein of MCL-1L. Compared to MCL-1L protein, MCL-1ES BH3M lacks the PEST motifs known to be involved in MCL-1L protein degradation and has seven mutated residues in BH3 domain critical for dimerization with BCL-2 family members. Overexpression of MCL-1ES BH3M induced death of different cells, and its cell killing effect was not blocked by forced expression of the pro-survival protein MCL-1L. Expression of MCL-1ES BH3M protein led to the activation of caspase 9 and caspase 3, suggesting apoptotic cell death, and confocal fluorescent microscopic analyses showed that MCL-1ES BH3M was partially localized in mitochondria. In conclusion, we reported a new apoptotic molecule and determined its cell death activity in cells.

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Enzymatic Modification of Soy Proteins: Effects of Functional Properties of Soy Isolate upon Proteolytic Hydrolysis (대두단백질(大豆蛋白質)의 효소적(酵素的) 변형(變形) : 분리대두단백질(分離大豆蛋白質)의 기능성(機能性)에 미치는 단백질가수분해(蛋白質加水分解)의 영향(影響))

  • Kang, Yeung-Joo
    • Korean Journal of Food Science and Technology
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    • v.16 no.2
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    • pp.211-217
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    • 1984
  • To study affinity of proteolytic enzymes to soy proteins, the physicochemical and functional properties of enzymatically modified protein products, kinetic parameters and degree of hydrolysis were measured using trypsin, alcalase (serine type protease) and pronase. Bacterial alcalase and pronase showed much greater affinity to soy protein than animal intestinal trypsin. This effect was very significant when unheated soy isolate was used as a substrate. Specific activities of these enzymes decreased with the increment of substrate concentration (over 2.0%, w/v) when heat denatured soy protein was used as a substrate. However, the decrease in specific activity was negligible at substrate concentrations lower than 2.0%. Polyacrylamide gel electrophoretic results showed that the pattern of 2S protein band changed distinctly in alcalase hydrolysis as compared with those of trypsin and pronase. Protein solubilities of alcalase and pronase hydrolyzates increased by 25-30%, at their pI (pH 5.0) over the control. Virtually no change was observed in solubility by trypsin hydrolysis. Heat coagulability and calcium-tolerance of the protein increased by enzymatic hydrolysis. No clear tendency, however, was observed for emulsion properties, foam expansion and the amount of free -SH groups. The enzyme treatment considerably decreased foam stability.

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