• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.4
• /
• pp.687-694
• /
• 1996

Myrosinase was purified from Korean mustard seed(Brassica juncea) by a sequential process of DEAE-cellulose, concanavalin A-sepharose, and Superose 6 chromatography. The molecular weight of puri-fied myrosinase(II-2) determined by SDS-polyacrylamide electrophoresis was 67KD. About a 248-fold purification for myrosinase II-2 was obtained after Superose 6 chromatography. Optimum pH of the myrosinase was 7.0 and optimum temperature of the enzyme was $3^{\circ}C.$ The enzyme was stable at pH 7.0, and below $30^{\circ}C.$ Cu, Hg and Fe ion significantly inhibited the enzyme activity, but ascorbic acid enhanced, resulting in a maximum activity by 1mM ascorbic acid. Among tile ascorbic acid ana-logues, dehydroascorbic acid inhibited the enzyme activity, whereas others showed a little effect. Reducing agents such as 2-mercaptoethanol and dithiothreitol inhibited the enzyme activity, but the reducing agents with ascorbic acid was enhanced enzyme activity.

• Applied Biological Chemistry
• /
• v.36 no.2
• /
• pp.86-92
• /
• 1993

Myrosinase from radish was purified by DEAE Bio-Gel, Con-A, and Superose-6 column. The purified myrosinase(II) possessed 2 subunits, and their molecular as determined by SDS-polyacrylamide gel electrophoresis were 53 and 39 KD, respectively. The specific activity of purified enzyme was 37,500 units/mg. The enzyme was purified approximately 44-fold compared to the crude enzyme. Optimum pH of the myrosinase was $6.5{\sim}7.0$ in phosphate and Tris-HCl buffer solutions. Optimum temperature of the enzyme was $37{\sim}38^{\circ}C$. The enzyme was stable at pH 7.0, and less than $30^{\circ}C$. Cu or Hg ion significantly inhibited the enzyme activity, but ascorbic acid enhanced, resulting in a maximum activity by 1 mM ascorbic acid. Among the ascorbic acid analogues, dehydroascorbic acid did not affect, whereas others showed a little effect, but less than ascorbic acid itself. Individual 2-mercaptoethanol and dithiothreitol (reducing agents) did not enhance the enzyme activity. but 2-mercaptoethanol effect was enhanced when mixed with ascorbic acid.

• Journal of the Korean Society of Food Culture
• /
• v.9 no.2
• /
• pp.137-142
• /
• 1994

Myrosinase in leaf mustard was purified and characterized to furnish a grounding information for utilizing the pungent taste and the potential antimicrobial capability of Dolsan leaf mustard to enhance the taste and storage life of kimchi. When myrosinase was purified from leaf mustard through a series of DEAE Sephadex, chromatofocusing and Con A Sepharose column chromatography, specific activity of the enzyme increased 7107-fold compared with that of crude enzyme preparation, and 18.8% yield was obtained. The purified myrosinase showed the optimum pH of 5.9, isoelectric point of 4.6, molecular weight of 129 kD, Km of 0.206 mM, and Vmax of $2.039\;{\mu}M{\cdot}min^{-1}{\cdot}mg\;protein^{-1}$, respectively. The optimum concentration of L-ascorbic for the maximum activity of the enzyme was 0.6 mM, and the enzyme activity decreased at a higher concentration of L-ascorbic acid than 0.6 mM, showing almost no enzyme activity at a L-ascorbic acid concentration of higher than 2.0 mM. Myrosinase activity in leaf mustard kimchi immediately after the kimchi was formulated was shown to be about 70 nmol/min/mg protein which decreased rapidly after 3 days of storage at $20^{\circ}C$, showing that less than half and almost none of the enzyme activity was retained in 4 and 10 days of storage, respectively.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.4
• /
• pp.563-569
• /
• 1995

Myrosinase from Korean cabbage(Bogdoli) was purified and its enzymatic properties were investigated. Myrosinase from the Korean cabbage was purified by DEAE Bio-Gel Sepharose, Concanavalin-A, and Mono-Q column chromatography and exhibited a 55KD molecular weight with a single band on the gel of SDS-PAGE. The enzyme was purified about 21-fold compared to its crude enzyme and a specific activity of purified enzyme was 15, 120units/mg. Optimum pH of the myrosinase was 7.0 in both phosphate and Tris-HCl buffer solutions, the enzyme was stable at pH 6.5~7.0. Optimum temperature of enzyme was 37~38$^{\circ}C$. The enzyme activity was significantly inhibited by Cu2+ and Hg2+, but enhanced by ascorbic acid, resulting in a maximum activity at 1mM ascorbic acid. Among the ascorbic acid analogues, dehydro-ascorbic acid did not affect, whereas others showed a little effect on the enzyme activity, but less than ascorbic acid itself. Reducing agents such as 2-mercaptoethanol and dithiothreitol had no effect on the enzyme activity, but the enzyme activity was enhanced when 2-mercaptoethanol was mixed with ascorbic acid.

• The Korean Journal of Food And Nutrition
• /
• v.34 no.1
• /
• pp.26-35
• /
• 2021

Myrosinases (thioglucosidases) catalyze the hydrolysis of a class of compounds called glucosinolates, of which the aglycones show various biological functions. It is often necessary to minimize the loss of myrosinase activity during thermal processing of cruciferous vegetables. Myrosinase was isolated from a popular spice, white mustard (Sinapis alba), and its thermal inactivation kinetics was investigated. The enzyme was extracted from white mustard seeds and purified by a sequential processes of ammonium sulfate fractionation, Concanavalin A-Sepharose column chromatography, and gel permeation chromatography. At least three isozymes were revealed by Concanavalin A-Sepharose column chromatography. The purity of the major myrosinase was examined by native polyacrylamide gel electrophoresis and on-gel activity staining with methyl red. The molecular weight of the major enzyme was estimated to be 171 kDa. When the consecutive step model was used for the thermal inactivation of the major myrosinase, its inactivation energy was 44.388 kJ/mol for the early stage of destruction and 32.019 kJ/mol for the late stage of destruction. When the distinct two enzymes model was used, the inactivation energy was 77.772 kJ/mol for the labile enzyme and 95.145 kJ/mol for the stable enzyme. The thermal inactivation energies lie within energy range causing nutrient destruction on heating.

• Korean Journal of Food Science and Technology
• /
• v.21 no.1
• /
• pp.136-144
• /
• 1989

The purification of myrosinase from radish roots was performed using Concannavalin A-Sepharose affinity chromatography and gel permeation HPLC, which gave a 22-fold-purification(S.P.A.=39,000 units/mg) with 50% recovery, SDS-polyacrylamide gel electrophoresis showed a single major band, suggestive of a relatively pure myrosinase, and the M.W. of the enzyme determined on gel permeation HPLC was ca. 124K. The enzyme showed on optimum pH of 6.5 and was stable at pH 6 to 7 at room temperature, but unstable below pH 4. The enzyme possessed an optimum temperature of $37^{\circ}C$, and gave a Vmax value of $40\;{\mu}moles/mg{\cdot}min$ and a Km value of 0.12mM for sinigrin. The purified myrosinase was activated maximally by 0.6mM of ascorbic acid, but somewhat inhibited by more than 2 mM ascorbic acid. The activities of myrosinase present in the peelings and the peeled radish amounted to approximately 1,333 units/g and 140 units/g weight, respectively and the peelings contained much more myrosinase activity than the peeled radish.

• Korean journal of food and cookery science
• /
• v.5 no.1
• /
• pp.1-8
• /
• 1989

The study on the change of general properties of Kagdugi during dfermentation reveals that around the third day of fermentation, optimum for good flavor, the pH decreased to around or below 4 while the acidity increased gradually. The relative amount of thiocyanate in the radish Kimchi homogenate decreased to 73% after 1 day and after 3 days to 32% of control. And the content of indolylmethyl glucosinolate and total myrosinase activity in the tissue of radish Kimchi decreased gradually and on 3rd day to 25% and 4% of control, respectively. On the other hand the concentration of ascorbic acid in the radish Kimchi was found to vary around 1mM. Based on these results, the gradual decline of thiocyanate formation in the radish Kimchi homogenate is concluded to be caused by the gradual decomposition of indolylmethyl glucosinolate and the decline of myrosinase activity, which are directly affected by the change of pH during fermentation.

• Korean journal of food and cookery science
• /
• v.26 no.1
• /
• pp.104-109
• /
• 2010

Korean Chinese cabbage (Brassica campestris L. ssp. pekinensis) is one of the major cruciferous vegetables. Cruciferous vegetables contain a series of relatively unique secondary metabolites of amino acids called glucosinolates. Although glucosinolates do not appear to be bioactive, they are hydrolyzed by plant myrosinase when the cells in plants are damaged, and release biologically active compounds such as isothiocyanates, nitriles, and thiocyanates. The objective of this study was to determine the myrosinase activity and total glucosinolate levels of Korean Chinese cabbages by different salting times (0, 12, 18, and 24 h) and salt concentrations (6, 10, 14%). The total water content, salt content, and pH of brined cabbages decreased with increasing salting time. The myrosinase activity as determined by a glucose kit, decreased with increasing salting time and salt content. The total glucosinolates were purified using an anion exchange column and measured by UV-visible spectrophotometer. The fresh Korean Chinese cabbages contained $25.38{\pm}1.45\;{\mu}mol/g$ dry weight of glucosinolates. However, the total glucosinolates of brined cabbages decreased with increasing salting time and salt concentration. After 24 h of salting time, the total glucosinolates of brined cabbages rapidly decreased by $16.12{\pm}11.09$, $11.25{\pm}10.91$, $9.29{\pm}10.73\;{\mu}mol/g$ in 6%, 10%, and 14% salt solution, respectively. Overall, the total glucosinolate levels of Korean Chinese cabbages were found to vary inversely with salting time and salt concentration.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2020.12a
• /
• pp.78-78
• /
• 2020

Cruciferous plants such as broccoli and radish contain glucosinolate, which is a bioactive precursor that is most often used in Korean foods and is unique as a food ingredient. In addition, it contains various other phytochemicals and is promising as a health-oriented food material. In particular, Sulforaphane is a hydrolyzate of the glucosinolate, which has a more beneficial effect on the human body. Glucosinolate may be hydrolyzed by enzymes called myrosinase, which is voluntarily possessed by cruciferous plants. However, the ESP(Epithiospecifier protein) in broccoli sprouts could acts competitively with myrosinase, and convert to the less bioactive sulforaphane nitrile form. Therefore, we improved the yielding of sulforaphane in broccoli sprouts with a new method. We induce inactivation of the ESP protein by heat treatment. At this time, a myrosinase was introduced from the radish sprout because myrosinase in broccoli sprouts is also denatured by heat treatment. According to the results, we have confirmed by GC / MS that formation of sulforaphane increases more than 7 fold using set heating and mixing conditions.

• Korean Journal of Food Science and Technology
• /
• v.24 no.4
• /
• pp.361-366
• /
• 1992

Studies were carried out on the factors responsible for the change of pungency in 'Kagdugi'. During fermentation, the pH in 'Kagdugi' decreased to around to 4, while acidity increased continuously. In accordance with the decrease of pungency, the content of 4-methylthio-3-butenyl isothiocyanate (MTB-NCS) in the homogenate of 'Kagdugi' decreased gradually and on 3rd day, the optimum period for good flavor, below 5% of that in the homogenate of fresh radish. The decrease of MTB-NCS formation was accompanied by the gradual loss of 4-methylthio-3-butenyl glucosinolate (MTB-glucosinolate), which was found to disappear more rapidly than total glucosinolate. Also, the ascorbic acid-dependent myrosinase activity was observed to decline gradually with the fermentation time, although the ascorbic acid content varied above the concentration required for maximal enzyme activity. Thus, it was suggested that the decline of MTB-NCS may be related to the gradual losses of MTB-glucosinolate content and myrosinase activity which are both susceptible to the effect of acidic pH.