scholarly journals Inhibitory Effect of Heat-Treated 3-(3^|^prime;,4^|^prime;-dihydroxyphenyl)-L-alanine (DOPA) on ^|^beta;-glucuronidase Activity

2013 ◽  
Vol 19 (6) ◽  
pp. 1115-1119
Author(s):  
Kei HASHIMOTO ◽  
Mika KINPARA ◽  
Yasushi UDA
1985 ◽  
Vol 48 (6) ◽  
pp. 494-498 ◽  
Author(s):  
B. EKSTRAND ◽  
W. M. A. MULLAN ◽  
A. WATERHOUSE

The antibacterial system, lactoperoxidase-H2O2-SCN− was affected by the presence of heated milk or skim milk reconstituted from powders having received severe heat treatment. This inhibitory effect was related to the increase in exposed sulfhydryl groups and to the redistribution of protein between micellar and whey phases. Chromatographic analyses of heat-treated milk showed that the inhibitory factor was associated with the casein micelle fraction. The inhibition, however, was overcome by addition of unheated skim milk.


1986 ◽  
Vol 53 (4) ◽  
pp. 601-613 ◽  
Author(s):  
Mary B. Grufferty ◽  
Patrick F. Fox

SummaryThe report that addition of KI03 (0·1 mm) to milk before ultra high temperature (UHT) treatment induces extensive proteolysis during subsequent storage at 37 °C was confirmed. None was produced by addition of H202 KMn04 or K2Cr207. The pH optimum for KI03-induced proteolysis was between 7·0 and 8·0 and the temperature optimum 37—45 °C. β-Casein was particularly susceptible and the proteolysis pattern was similar to that caused by indigenous alkaline milk proteinase (MPA, plasmin). Addition of plasmin to milk before UHT treatment (140 °C/10 s) caused slight proteolysis during subsequent storage but addition of 0·1 mm-KI03 and plasmin caused extensive proteolysis which was prevented by addition of soyabean trypsin inhibitor, indicating the probable involvement of plasmin in KI03-induced proteolysis in UHT-treated milk. Equally extensive proteolysis occurred in serum protein-free casein micelle systems (SPFCM), with or without KI03, during storage at 37 °C following UHT treatment, indicating a role for whey proteins in KI03-induced proteolysis. Addition of β-lactoglobulin (β-lg) to a SPFCM system inhibited proteolysis, but extensive proteolysis occurred in a SPFCM system containing both β-lg and KI03. MPA-free Na caseinate (prepared by heating at 140 °C for 7 min) underwent extensive proteolysis when treated with plasmin before UHT treatment; proteolysis was inhibited by addition of °-lg to this system and KI03 reversed the inhibitory effect of β-lg. Plasmin proteolysis of isolated αs1-casein was inhibited by denatured β-lg (90 °C/30 min) at a level of 4 mg/ml but not by native β-lg. When denatured in the presence of KI03, β-lg had a lower free SH content than the control and was less inhibitory for plasmin in proteolysis of isolated αsl-casein. The results show that denatured β-lg inhibits plasmin proteolysis of caseins in UHT milk and that inhibition is prevented by KI03. This inhibition may occur via thiol–disulphide interchange, which is prevented if the SH group of ²-lg is oxidized by KI03, thus permitting the stimulatory effect of KI03 on proteolysis in UHT-treated milk.


2020 ◽  
Vol 11 (1) ◽  
pp. 7921-7931

In neonatal jaundice, β-glucuronidase converts conjugated bilirubin into the unconjugated form and increases its level in the blood. Many natural compounds have been identified as β-glucuronidase inhibitors. The aim of this study was to evaluate the effect of hydro-methanolic extracts of 100 plants on β-glucuronidase. The β-glucuronidase activity was measured by a spectrophotometric method using Phenolphthalein glucuronide and 4-nitrophenyl β-D-glucuronide. Kinetic study of the enzyme was performed in the presence and absence of the plant extract. It was revealed that from hydro-methanolic (70%) extracts, Rosa damascena and Ipomoea tricolor showed more than 85% inhibitory effect on β-glucuronidase. Rosa damascena showed competitive inhibition, and Ipomoea tricolor showed non-competitive inhibition. The Km and Vmax values for β-glucuronidase were 23.32 mM and 0.814 mM min-1, respectively. When using 4-nitrophenyl β-D-glucuronide, Stevia and Cerasus avium showed more than 65% inhibitory effect on β-glucuronidase. Both Stevia and Cerasus avium showed non-competitive inhibition. The Km and Vmax values for β-glucuronidase were 16.98 mM and 0.936 mM min-1, respectively. None of the plant extracts showed an activation effect on the enzyme. The data suggest that these plants might be good candidates for the treatment of neonatal jaundice and its related diseases.


2021 ◽  
Vol 27 (5) ◽  
pp. 797-806
Author(s):  
Makoto Kuji ◽  
Nanako Itoh ◽  
Yui Ohba ◽  
Kiyoshi Yamada ◽  
Kei Hashimoto

Author(s):  
Selda Bulca ◽  
Atakan Koç

The main purpose of this study was to investigate the possibilities of technological production of camel milk yoghurt. First of all, denaturation of antimicrobial substances in camel milk by heat treatment and their effects on pH decrease and on the viscosity were analysed. Although the pH decrease was present, the viscosity of camel milk didn’t change. In the study, two different heat treatments (20 min at 90°C and 20 min at 95°C) were applied to camel milk and pH and SH (Soxhelet Henkel) values were determined until pH reached 4.7 during fermentation. After culture addition the pH drop was at 90°C for 20 minutes heat-treated camel milk slower than the camel milk heated at 95°C for 20 minutes. Similarly, the increase in SH in the cultured milk treated at 90°C for 20 minutes was slower than the increase in SH in the cultured milk treated at 95°C for 20 minutes. In the next study, viscosity and pH changes in yoghurt produced from cow and camel milk were compared. For this purpose, both milks were heat treated at 80°C for 20 minutes. After 180 minutes in cow’s milk, the viscosity was 9891 mPa.s, and after 210 minutes it reached 25237 mPa.s. In contrast, the viscosity in cultured camel milk was determined as 1210 mPa.s after 90 minutes, while the viscosity remained around 1216 mPa.s after 380 minutes. In the next study, for the production of yogurt from cow milk and camel milk were performed. Both milks were heat treated at 80°C for 20 minutes and changes in viscosity and drop of pH during fermentation were analysed. After the 180 minutes of fermentation in cow’s milk the viscosity came to 9891 mPa.s, after 210 minutes it was 25237 mPa.s. In contrast, after 90 minutes in the cultured camel milk, the viscosity was 1210 mPa.s, while after 380 minutes the viscosity reached to 1216 mPa.s. E. coli, L. bulgaricus and Listeria innocua were used to determine the antimicrobial effect of raw camel milk, cow milk, heat treated camel and cow milk camel colostrum. While camel milk and colostrum had inhibitory effect on E. coli, L. bulgaricus, Listeria innocua was not inhibited


This paper considers the inhibition effect of Aloe Vera on the selected aluminium alloys in 10 % sulfuric acid and 3 % sodium chloride solutions at room temperature, using methods of potentiodynamic polarisation and cyclic voltammetry. The study involved as-cast and heat-treated 2xxx alloys, with the scanning speed of 1mV/s for linear polarisation and 50 mV/s for cyclic voltammetry. The various constant potential was applied for each tested alloy. Polarisation results indicate that the transpassivation occurs in an acid medium in case of each alloy. The obtained results indicate that Aloe vera extract acts as a cathodic inhibitor.


1982 ◽  
Vol 45 (14) ◽  
pp. 1310-1313 ◽  
Author(s):  
YUH-MEI CHUNG ◽  
J. S. LEE

Microorganisms isolated from seafood showed various degrees of sensitivity toward potassium sorbate (PS). At pH 7.0, PS concentration of 0.53% completely inhibited growth of Moraxella sp., while 2.73% was needed to inhibit Arthrobacter sp. Pseudomonas I sp., which was relatively resistant to PS (inhibitory concentration = 1.62%), was not affected by 0.3% PS after freeze-thaw treatment (−78°C for 8 min and 20°C for 20 min), but showed a delay in onset of logarithmic growth for up to 20 h after heating at 50°C for 5 min. The inhibitory effect of PS on sub-lethally injured Pseudomonas I was greater in basal medium (Minimum Broth, Davis) than in a rich medium (tryptone-peptone-extract, TPE). Alteromonas putrefaciens, which was sensitive to PS (inhibitory concentration = 0.74%), was also sensitive to freeze-thaw and mild heat. The lag period for quick-frozen cells was extended by 14 h in the presence of 0.05% PS. Heating at 45°C for 10 sec was sufficient to cause complete inhibition of growth by 0.05% PS in MBD, and 8 h delay in the onset of logarithmic growth in TPE. Selective and inhibitory effects of PS, therefore, could be further enhanced in frozen or heat-treated seafood.


2013 ◽  
Vol 77 (11) ◽  
pp. 2325-2327 ◽  
Author(s):  
Yuko WATANABE ◽  
Ryoko MUROI ◽  
Haruna TSUCHIYA ◽  
Yasushi UDA ◽  
Kei HASHIMOTO

Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).


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