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101.
Nigel T. Faithfull 《Journal of the science of food and agriculture》1984,35(8):819-826
The origins and development of in-vitro techniques for the determination of the apparent digestibility of ruminant feedstuffs are critically reviewed. Special attention is given to the effect of the pH used for the pepsin digestion stage, its optimum value, and its solubilising effect upon various mineral compounds and protein- and mineral-tannin complexes formed in the ruminant digestive system. New experimental evidence is presented concerning the latter effect. Comparisons are made with the Tilley and Terry method in widespread use at the present time. 相似文献
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103.
Panagiotis G. Doukas Dimitra P. Vageli Clarence T. Sasaki Benjamin L. Judson 《International journal of molecular sciences》2021,22(8)
Pepsin refluxate is considered a risk factor for laryngopharyngeal carcinogenesis. Non-acidic pepsin was previously linked to an inflammatory and tumorigenic effect on laryngopharyngeal cells in vitro. Yet there is no clear evidence of the pepsin-effect on a specific oncogenic pathway and the importance of pH in this process. We hypothesized that less acidic pepsin triggers the activation of a specific oncogenic factor and related-signalling pathway. To explore the pepsin-effect in vitro, we performed intermittent exposure of 15 min, once per day, for a 5-day period, of human hypopharyngeal primary cells (HCs) to pepsin (1 mg/mL), at a weakly acidic pH of 5.0, a slightly acidic pH of 6.0, and a neutral pH of 7.0. We have documented that the extracellular environment at pH 6.0, and particularly pH 7.0, vs. pH 5.0, promotes the pepsin-effect on HCs, causing increased internalized pepsin and cell viability, a pronounced activation of EGFR accompanied by NF-κB and STAT3 activation, and a significant upregulation of EGFR, AKT1, mTOR, IL1β, TNF-α, RELA(p65), BCL-2, IL6 and STAT3. We herein provide new evidence of the pepsin-effect on oncogenic EGFR activation and its related-signaling pathway at neutral and slightly acidic pH in HCs, opening a window to further explore the prevention and therapeutic approach of laryngopharyngeal reflux disease. 相似文献
104.
Sitthipong Nalinanon Soottawat Benjakul Hideki Kishimura 《Journal of the science of food and agriculture》2010,90(9):1492-1500
BACKGROUND: Due to the low extraction efficiency of collagen from fish skin by the typical acid solubilization process, pepsin has been widely used to aid further extraction of collagen from the residue. The aim of this study was to characterize collagen from the skin of arabesque greenling extracted with the aid of albacore tuna pepsin, in comparison with collagen obtained from the acid solubilization process. RESULTS: Acid‐solubilized collagen (ASC) from the skin of arabesque greenling was extracted with acetic acid. Pepsin‐solubilized collagen (PSC) was further extracted from the skin residue with the aid of pepsin from albacore tuna. The yields of ASC and PSC were 303 and 140 g kg?1 (dry weight), respectively. Both collagens contained α‐ and β‐chains as their major components and were characterized as type I collagen. Both collagens contained glycine as a major amino acid and had imino acid content of 157–159 residues per 1000 residues. The degradation induced by lysyl endopeptidase and V8‐protease was more pronounced in PSC compared with ASC. Maximal transition temperatures of both collagens were in the range of 15.4–15.7 °C. Fourier transform infrared spectra revealed some differences in molecular order between ASC and PSC. Nevertheless, the triple‐helical structure of PSC was still predominant. Based on ζ‐potential, pI of ASC and PSC was estimated to be 6.31 and 6.38, respectively. CONCLUSION: Isolation of collagens from the skin of arabesque greenling could be achieved by acid or albacore tuna pepsin solubilization. However, there was a slight difference in properties between ASC and PSC. Copyright © 2010 Society of Chemical Industry 相似文献
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106.
氨基树脂固定胃蛋白酶的方法及性质研究 总被引:1,自引:0,他引:1
采用氨基树脂作为载体,戊二醛作为交联剂,对胃蛋白酶的固定化进行了研究,并对固定化条件和固定化胃蛋白酶的部分酶学性质进行了分析。确定固定条件为:戊二醛浓度为5%,载体处理温度为室温(25℃),处理时间为5h,m(胃蛋白酶):m(氨基树脂)为1:25,pH为3.0,固定时间为12h。此条件下固定化的胃蛋白酶活力为30U/g,酶的活力回收率为60%。与非固定化相比最适水解温度由50℃升高到60℃,最适pH值由2.0升高到4.0,游离酶米氏常数3.08g/L,固定化酶米氏常数1.2g/L,固定化胃蛋白酶的储存半衰期约为25天。对珠蛋白的操作半衰期为9天。 相似文献
107.
Phanat Kittiphattanabawon Soottawat Benjakul Sittichoke Sinthusamran Hideki Kishimura 《International Journal of Food Science & Technology》2015,50(9):1972-1978
Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the skin of clown featherback (Chitala ornata) were isolated and characterised. Yields of ASC and PSC were 27.64 and 44.63% (dry weight basis) with total collagen recovery of 82.08%. Both collagens contained glycine as the major amino acid with relatively high content of proline, hydroxyproline and glutamic acid/glutamine. Nevertheless, they had the low content of cysteine, histidine and tryrosine. The collagen was characterised as type I, comprising (α1)2α2‐heterotrimer. Pepsin‐aided process did not affect triple‐helical structure of PSC as determined by FTIR spectra. Thermal transition temperature of ASC (36.28 °C) was slightly higher than that of PSC (35.23 °C). However, no differences in isoelectric point (5.54–5.68) between ASC and PSC were observed. Therefore, collagen from the skin of clown featherback could be successfully extracted for further applications. 相似文献
108.
Acid‐soluble and pepsin‐soluble collagens from grass carp (Ctenopharyngodon idella) skin: a comparative study on physicochemical properties 下载免费PDF全文
In this study, acid‐soluble (ASC) and pepsin‐soluble (PSC) collagens with triple helical structures were successfully extracted from the skin of grass carp (Ctenopharyngodon idella) by two different extraction approaches. SDS‐PAGE pattern revealed that ASC and PSC are type I collagens with typical α1, α2 and β‐chains. In addition, the intensity of χ‐chain (trimer) in ASC was higher than that of PSC, representing the presence of the high proportion of intra‐ and intermolecular cross‐links of extracted collagens with large molecular weight using the acid method. Differential scanning calorimetry (DSC) results demonstrate that Td (69.04 °C) of ASC was higher than Td (62.20 °C) of PSC. Both ASC and PSC had the highest solubility at acidic pHs or at a low concentration of NaCl (<2%, w/v). The results of FTIR suggested the ASC and PSC maintained in the helical secondary structure at high degree. 相似文献
109.
目的研究止疡冲剂对大鼠实验性胃溃疡的作用。方法应用大鼠应激型胃溃疡模型、大鼠醋酸灼烧型胃溃疡模型和大鼠幽门结扎型胃溃疡模型,以溃疡指数和溃疡面积为指标,观察止疡冲剂灌胃(ig)给药对胃溃疡的抑制作用;以幽门结扎法收集胃液,观察对胃液分泌的影响。结果止疡冲剂(100,200,400mg·kg-1,ig)能明显降低胃溃疡模型大鼠胃黏膜的溃疡指数,缩小溃疡面积,抑制胃酸分泌,增加胃液pH,减少胃液分泌和降低胃蛋白酶活性。结论止疡冲剂对大鼠实验性胃溃疡具有明显的保护作用。 相似文献
110.