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利用重组色氨酸合成酶催化合成5-羟基色氨酸,考察了pH、反应温度、底物摩尔比和底物浓度对色氨酸合成酶酶活的影响。最佳转化条件为:反应温度为35 篊,pH为9,5-羟基吲哚与工业角蛋白水解氨基酸液中L-丝氨酸的适宜底物摩尔比为1.1: 1,底物工业角蛋白水解氨基酸液中L-丝氨酸最适合浓度为200 mmol/L,反应达到平衡时间为18 h,底物L-丝氨酸摩尔转化率达到86%。 相似文献
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为资源化利用动物血液,以血粉为原料制备氨基酸水溶肥。通过单因素实验研究液料比、原料预处理温度、蛋白酶种类及组合酶比例等因素对血粉蛋白酶解效果的影响;通过正交实验考察温度、酶制剂添加量、p H和时间对血粉蛋白酶解效果的影响。结果表明:血粉的最佳酶解工艺为液料体积质量比6 mL/g、温度55℃、组合酶添加量3.0%(组合酶中蛋白酶B与风味蛋白酶质量比为2∶1)、p H 8.0、时间12 h;在该工艺条件下,血粉蛋白水解度为67.26%,酶解液中19种游离氨基酸质量分数为6.39%,分子量在1 046 Da以下的多肽占比达到99.59%。通过对血粉酶解工艺的优化,提高了血粉蛋白的水解度,增加酶解液中氨基酸含量,为蛋白酶酶解血液制备氨基酸水溶肥的过程控制及规模应用提供理论指导。 相似文献
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均匀设计优选双酶法分步水解甲鱼蛋白质最佳条件 总被引:2,自引:0,他引:2
采用木瓜蛋白酶、胰蛋白酶2种酶分步水解技术,对甲鱼蛋白质进行水解.利用均匀设计法研究上述2种酶分步水解甲鱼蛋白质的最佳工艺条件为:原料∶水=1∶3.5,木瓜蛋白酶用量18.0 g·kg-1,温度50 ℃,pH值6.9,水解时间5.5 h;而胰蛋白酶用量28.0 g·kg-1,温度50 ℃,pH 7.5,水解时间4 h.所得水解液的氨基氮含量为7906.5 mg·kg-1,水解液游离氨基酸的含量为626.7 mg·(100 mL)-1,其中必需氨基酸的含量为211.35 mg·(100 mL)-1. 相似文献
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For the purpose of obtaining two protein hydrolysates from peptiona (Arca zebra), to be used as nutritional ingredients in accepted food items destined for human consumption, the enzymes bromelain and papain were studied. The effect of adding each of these proteases, on the rate of hydrolysis and conversion extent of insoluble pepitona protein to soluble nitrogen, were examined. Distilled water was added to the raw material to give a 2:1 ratio of solvent to pepitona, and mixed to produce a slurry at a pH of 6.4-6.5, with a total nitrogen value of 0.97% (w/v). Optimum conditions of hydrolysis were found to be two hours at 40 degrees C for both enzymes, at a pH of 7 and 0.3 g enzyme/100 g pepitona for papain, and a 0.2 g enzyme/100 g pepitona at pH 6.4 normally found in pepitona in the case of bromelain. 相似文献
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Sesame (Sesamum indicum, L.) is one of the most important oilseed crops in Venezuela. However, the low solubility of the flour made of commercial meals does not allow its use in the preparation of fluid foods. To solve this situation, the alternative of solubilizing the sesame proteins by an enzymatic method, using commercial proteases, was studied. Hydrolysis was carried out with two types of bacterial proteases: neutrasa 0.5L, and alcalase 0.6L. Basically, the process consisted of milling and sieving the sesame cake (60 mesh), concentrating the proteins by solubilizing them at a pH of 9.5, and then precipitating at a pH of 4.5. Proteins were hydrolyzed by an enzymatic method, and the hydrolysates freeze-dried and spray-dried. Optimal conditions of hydrolysis using neutrase 0.5L at a pH of 7 were: 6% substrate concentration, 3% enzyme:substrate ratio, temperature 50 degrees +/- 1 degree C, and hydrolysis degree of 8%. When alcalase 0.6L was used at a pH of 8, optimal conditions were: 8% substrate concentration, 2.3% enzyme:substrate ratio, temperature 58 degrees +/- 1 degree C, and hydrolysis degree of 10%. The enzyme affinity (Km) was best at temperatures near the optimal temperature for the hydrolysates. Dried hydrolysates had protein values which ranged between 66.3% and 66.9% and a nitrogen solubility in water, of approximately 85%. Hydrolysis yields referred to the concentrate dried mass were 42% for the atomized hydrolysate, and 56% for the freeze-dried one. In conclusion, the enzymatic hydrolysis process improved the nitrogen solubility in water of the sesame proteins. 相似文献
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W. L. Levadoux M. L. Kalmokoff M. D. Pickard J. W. D. GrootWassink 《Journal of the American Oil Chemists' Society》1987,64(1):139-144
Frost-damaged or prematurely harvested canola seed (rapeseed) may yield oil with a high chlorophyll content (50–60 μg/ml).
Enzymatic hydrolysis of chlorophyll, added to buffer/surfactant, buffer/acetone or buffer/acetone/canola oil, to produce water-soluble
chlorophyllide (green pigment) was studied using a crude chlorophyllase preparation (acetone-dried chloroplasts) from 15 to
20-day-old sugar beet seedlings. In buffer/surfactant, the optimum pH for enzyme activity was temperature dependent. At 30
C and 0.24% Triton X-100 (or 30% acetone), chlorophyllase showed maximum activity toward a crude chlorophyll preparation over
the range of pH 8–10. At 60 C, the activity was more than twofold higher, with a sharp maximum at ∼pH 8. Mg2+ enhanced the activity with an optimal concentration of 50 mM. At pH 7.5, 50 C and in the presence of only 6% acetone, the
enzyme showed high affinity for chlorophyll (Km=15μM or 13.5 μg/ml), suggesting that the natural chlorophyll concentrations
found in green canola oils might facilitate high enzymatic efficiencies. The crude enzyme was stable in buffer/acetone at
pH 7.5 and 50 C for at least two hr.
With acetone concentrations as low as 6%, maximum enzyme activities in buffer and buffer/canola oil required intensive mixing
(homogenization) of the various substrate, enzyme and liquid phases. In general, the rate and extent of chlorophyll hydrolysis
were greater in buffer than in buffer/oil. In both reaction systems, chlorophyll hydrolysis slowed down with time due to accumulation
of phytol, which proved to be a competitive inhibitor (Ki=11 μM or 3.3 μg/ml). The other hydrolysis product, chlorophyllide, did not affect enzymatic activity.
Crude canola oil used in the reconstitution of green oil did not support enzymatic chlorophyll hydrolysis without prior degumming
and desoaping. The optimum buffer/oil ratio of the reaction mixtures was above 2/1 (v/v). 相似文献
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Raheleh Ghanbari Mohammad Zarei Afshin Ebrahimpour Azizah Abdul-Hamid Amin Ismail Nazamid Saari 《International journal of molecular sciences》2015,16(12):28870-28885
In recent years, food protein-derived hydrolysates have received considerable attention because of their numerous health benefits. Amongst the hydrolysates, those with anti-hypertensive and anti-oxidative activities are receiving special attention as both activities can play significant roles in preventing cardiovascular diseases. The present study investigated the angiotensin-I converting enzyme (ACE) inhibitory and anti-oxidative activities of Actinopyga lecanora (A. lecanora) hydrolysates, which had been prepared by alcalase, papain, bromelain, flavourzyme, pepsin, and trypsin under their optimum conditions. The alcalase hydrolysate showed the highest ACE inhibitory activity (69.8%) after 8 h of hydrolysis while the highest anti-oxidative activities measured by 2,2-diphenyl 1-1-picrylhydrazyl radical scavenging (DPPH) (56.00%) and ferrous ion-chelating (FIC) (59.00%) methods were exhibited after 24 h and 8 h of hydrolysis, respectively. The ACE-inhibitory and anti-oxidative activities displayed dose-dependent trends, and increased with increasing protein hydrolysate concentrations. Moreover, strong positive correlations between angiotensin-I converting enzyme (ACE) inhibitory and anti-oxidative activities were also observed. This study indicates that A. lecanora hydrolysate can be exploited as a source of functional food owing to its anti-oxidant as well as anti-hypertension functions. 相似文献
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Process parameters on enzymatic hydrolysis and molecular weight (MW) distribution of whey protein hydrolysates were investigated. Whey protein hydrolysates were first gained by the alkaline protease alcalase for 7 h at temperature (50 °C), pH (8.0) and E/S (3%). The diversification of the hydrolysis degree and dissociative amino acid content was investigated during the whey hydrolysis. The dissociative amino acid content was 56.09 μmol/mL with the hydrolysis degree of 20.04%. The results of Sephadex G25 washing and high performance liquid chromatography–electrospray ionization–mass spectrometry (HPLC–ESI–MS) indicated the molecular weight distribution of whey protein hydrolysates ranged from 300 to 1400 Da, and most of whey peptide was under 1000 Da. 相似文献
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钒铅锌矿含有多种有价金属,V品位高,具有较高的经济价值。本工作采用硫酸浸出法从该矿中提取钒锌,对浸出过程热力学进行分析,通过条件实验研究硫酸浓度、液固比、浸出时间、搅拌速率、浸出温度等条件对钒、铅、锌等主要有价金属浸出率的影响。结果表明,在较高pH值及较高温度下,浸出液中V会出现水解,含V的水解产物留在浸出渣中影响V浸出率。得到最优浸出条件为:硫酸浓度200 g/L,液固比3:1,浸出时间30 min,搅拌速率200 r/min,浸出温度为30℃。最优条件下V浸出率可达97.90%,Zn浸出率为97.11%,Fe浸出率<1%,Pb浸出率<0.01%。动力学分析结果表明,浸出过程的反应速率受扩散过程控制。酸浸过程使V和Zn进入浸出液,Pb和Fe留在浸出渣中,所得浸出液可使用离子交换或萃取法分离V和Zn。浸出渣中含钒0.41wt%、锌0.61wt%、铁15.50wt%、铅47.70wt%,主要成分为PbSO4和FeO(OH),可返回火法炼铅系统。 相似文献
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In Vitro Acetylcholinesterase-Inhibitory Properties of Enzymatic Hemp Seed Protein Hydrolysates 下载免费PDF全文
The aim of this work was to characterize the structural and functional properties of hemp seed protein‐derived acetylcholinesterase (AChE)‐inhibitory enzymatic hydrolysates. Hemp seed protein isolate hydrolysis was performed using six different proteases (pepsin, papain, thermoase, flavourzyme, alcalase and pepsin + pancreatin) at different concentrations (1–4 %). The degree of hydrolysis was directly related to the amount of protease used but had no relationship with AChE‐inhibitory activity. Amino acid composition results showed that the hemp seed protein hydrolysates (HPHs) had high levels of negatively charged amino acids (39.62–40.18 %) as well as arginine. The 1 % pepsin HPH was the most active AChE inhibitor with ~6 µg/mL IC50 value when compared to 8–11.6 µg/mL for the other HPHs. Mass spectrometry analysis showed that most of the peptides in all the hydrolysates were less than 1000 Da in size. However, the pepsin HPHs contained larger‐sized peptides (244–1009 Da) than the papain HPHs (246–758 Da), which in turn was larger than the alcalase HPH (246–607 Da). The higher AChE‐inhibitory effects of the pepsin HPHs may be due to increased synergistic effects from a wider peptide size range when compared to the papain and alcalase HPHs that had narrower ranges. The narrow peptide size range in the alcalase HPH confirms the higher efficiency of this protease in releasing small‐sized peptides from food proteins. 相似文献
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Mónica Marcos María Teresa García‐Cubero Gerardo González‐Benito Mónica Coca Silvia Bolado Susana Lucas 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(2):237-246
BACKGROUND: The enzymatic hydrolysis of steam‐exploded wheat straw using commercial enzyme complexes has been studied. A cellulase enzyme complex (Accellerase 1500), along with specific xylanase complements (Accellerase‐XC and Accellerase‐XY) provided by Genencor, have been used to enhance glucose and xylose recovery. A systematic study with response surface methodology (RSM) was used to check the effect of the operating conditions: pH (4–5), temperature (50–60 °C) and enzyme/substrate ratio (0.1–0.5 mL gcellulose?1) on the enzymatic hydrolysis with Acellerase 1500 to maximize the sugar yield. Xylanases were used as complements to increase the release of xylose. RESULT: Statistical results from ANOVA analysis demonstrated that the enzymatic hydrolysis was clearly improved by temperature and enzyme/substrate ratio. The optimum conditions for higher glucose and xylose releases were obtained with the higher enzyme dosage ratio (0.5 mL g?1cellulose), 50 °C and pH 4. CONCLUSION: Model validation at optimum operating conditions showed good agreement between the experimental results and the predicted responses for a confidence level of 95%. The use of the xylanase complements, Accellerase‐XY (accessory xylanase enzyme complex) and Accellerase‐XC (accessory xylanase/cellulase enzyme complex), increases the conversion of hemicellulose. Accellerase‐XC supplementation was more effective, obtaining an increase in yields of glucose and xylose of 11.8% and 23.6%, respectively, using a dosage of 0.125 mL g?1cellulose. © 2012 Society of Chemical Industry 相似文献