• Journal of Microbiology and Biotechnology
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• 제16권7호
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• pp.1111-1119
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• 2006

Beauvericins and enniatins are cyclohexadepsipeptides exhibiting various biological activities on animal systems, including humans. Fusarium oxysporum FB1501 (KFCC 11363P) that produces four different cyclohexadepsipeptides was isolated from soil in Korea and the structures of the four cyclohexadepsipeptides elucidated by HPLC, MS, IR, and NMR analyses. The molecular weights for compounds 1,2,3, and 4 were determined to be 654.5, 784.5, 668.6, and 682.5, respectively, on the basis of ESI-MS measurements. The IR spectra for all the compounds exhibited absorptions for ester $(1,733-1,743\;cm^{-1})$ and amide $(1,649-1,655\;cm^{-1})$ bonds that were very similar to those for beauvericin and enniatins with ester and amide absorptions. The results of the NMR analysis $(^{1}H,\;^{13}C,\;135-DEPT,\;COSY,\;HMQC,\;and\;HMBC;\;in\;COCl_{3})$ revealed that compounds 1,3, and 4 consisted of $_{L}-N-methyl\;valine$ (N-MeVal), $_{D}-{\alpha}-hydroxyisovaleic\;acid$ (Hiv), and 2-hydroxy-3-methylpentanoic acid (Hmp) residues (compound 1: three N-MeVal residues, two Hiv residues, and one Hmp residue; compound 3: three N-MeVal residues, one Hiv, and two Hmp residues; compound 4: three N-MeVal residues and three Hmp residues). Therefore, the compounds were identified as enniatin H (compound 1), enniatin I (compound 3), and enniatin MK1688 (compound 4). Compound 2 was analyzed as beauvericin according to 1D and 2D NMR analyses. This study is the first report related to the co-production of beauvericin with other unusual enniatins, such as enniatin H, enniatin I, and enniatin MK1688, by Fusarium oxysporum.

• 한국식품위생안전성학회지
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• 제37권5호
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• pp.347-355
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• 2022

본 연구에서는 국내산 생강(n = 43)과 생강가루(n = 31)를 대상으로 beauvericin (BEA)과 enniatins (ENNs)의 오염 실태를 조사하였다. 생강 시료 중 62.79%가 BEA에 오염되었으며, 최대 오염농도는 640.07 ㎍/kg으로 오염률과 오염농도가 조사 대상 독소 중 가장 높았다. 생강에서 ENNs의 오염률은 최대 11.63% (ENB, ENB1)이었으며, 최대 오염농도는 91.02 ㎍/kg (ENA)였다. 생강가루에서는 ENB의 오염률이 70.97%로 가장 높았으나, 오염농도는 BEA이 최대 1, 344.18 ㎍/kg으로 조사 대상 독소 중 가장 높았다. 생강가루의 ENA, ENA1, ENB, ENB1의 오염률은 29.03%, 22.58%, 70.97%, 35.48%였으며, 최대 오염농도는 220.45 ㎍/kg, 156.61 ㎍/kg, 413.99 ㎍/kg, 70.29 ㎍/kg로 ENB의 오염률과 오염농도가 높았다. BEA과 ENNs은 생강보다 생강가루에서 오염농도가 높았다. 생강과 생강가루에서 BEA과 ENNs의 중복 오염률은 각각 16.28%와 64.52%로 생강에 비해 생강가루에서 독소의 중복오염률이 높았다. 본 연구는 한국산 생강과 생강가루의 BEA과 ENNs의 발생 및 이들의 중복 오염을 처음으로 보고하는 것이다.

• 한국식품위생안전성학회지
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• 제23권1호
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• pp.73-79
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• 2008

Beauvericin과 enniatin H, I, 그리고 MK1688의 생산에 미치는 온도와 수분함량의 효과를 조사하였다. 쌀을 기질로 할 경우 $25^{\circ}C$, 40% 수분함량에서 조사된 모든 독소들이 최대로 생산되었으며, $15^{\circ}C$의 온도에서 접종 2주 후 $50\;{\mu}g/g$이하의 생성량을 나타내었다. 수분함량 10%에서도 접종 후 6주차에 모든 독소들의 검출이 확인되었으며, 이는 이 독소들이 0.75정도의 낮은 수분활성도에서도 생성될 수 있음을 나타낸다. 한편, 국내에서 생산된 곡류들(65종)에 대하여 Fusarium 독소인 beauvericin의 오염을 분석하였다. 국내에서 수확된 65종의 곡류시료 중 6종의 시료에서 beauvericin오염이 확인되었다. 쌀과 현미에서는 beauvericin이 검출되지 않았으며, 2004년산 옥수수 3종, 2004년과 2005산 보리 시료 각 1종, 그리고 2005년 재배된 밀 1종에서 beauvericin이 검출되었다. 가장 높은 오염도를 보인 것은 옥수수 시료이며, 이 시료에서 $0.23\;{\mu}g/g$의 beauvericin이 검출되었다. 국내에서는 beauvericin에 대한 곡류 오염 조사가 이 연구에서 처음으로 이루어졌으며, 국내산 곡류에서도 beauvercin이 검출됨에 따라 지속적으로 오염도를 조사할 필요가 있다.

• BMB Reports
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• 제33권3호
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• pp.228-233
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• 2000

The steady-state investigation of the mechanism of Dhydroxyisovalerate dehydrogenase was performed in order to understand this type of kinetic patterns. The initial velocity was measured with various amounts of both substrates, NADPH and 2-ketoisovalerate. Double reciprocal plots gave patterns that conversed on or near the abscissa. Binding studies indicated that NADPH bound first to the enzyme. The product $NADP^+$ was found to be a competitive inhibitor with respect to NADPH at a constant concentration of 2-ketoisovalerate. However, it showed noncompetitive inhibition against 2-ketoisovalerate at a fixed amount of NADPH. Another product, D-hydroxyisovalerate, was a non-competitive inhibitor versus NADPH and 2-ketoisovalerate at constant levels of 2-ketoisovalerate and NADPH, respectively. These results were comparable with an ordered bi-bi mechanism, in which NADPH bound first to the enzyme, followed by the binding of 2- ketoisovalerate. $NADP^+$ is the last product to be released. The ordered reaction manner of D-hydroxyisovalerate dehydrogenase from 2-ketoisovalerate to D-hydroxyisovalerate allows the accurate regulation of valine metabolism and it may lead to the regulation of total biosynthesis of enniatins in the Fusarium species.

• BMB Reports
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• 제29권6호
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• pp.493-499
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• 1996

The biochemical properties of purified D-hydruxyisovalerate dehydrogenase from Fusarium sambucinum was elucidated. D-Hydroxyisovalerate dehydrogenase produced solely D-hydroxyisovalerate from 2-ketoisovalerate. The isoelectric point of the purified enzyme was 7.0. The enzyme was highly specific with 2-ketoisovalerate ($K_{m}=0.188$ mM, $V_{max}=8.814$ mmol/min mg) and 2-keto-3-methyl-n-valerate ($K_{m}=0.4$ mM, $V_{max}=1.851$ mmol/min mg) for the reductive reaction. This was also seen by comparing D-hydroxyisovalerate ($K_{m}=1.667$ mM, $V_{max}=0.407$ mmol/min mg) and D-hydroxy-3-methyl-n-valerate ($K_{m}=6.7$ mM, $V_{max}=0.648$ mmol/min mg) for the oxidative reaction. Thiol blocking reagents, such as iodoacetamide, N-ethylmaleimide and p-chloromecuribenzoate inhibited about 80% of enzyme activity at 0.02 mM, 50 mM and 50 mM, respectively. The enzyme activity was also inhibited by the addition of 0.1 mM of various metal ions, such as $Fe^{2+}$ (67%), $Cu^{2+}$ (88%), $Zn^{2+}$ t (76%) and $Mg^{2+}$ (9%). The enzyme was stable over three months in 50 mM potassium phosphate buffer (pH 5~7) at $-80^{\circ}C$. However the purified enzyme lost 30% of its activity in the same buffer after 24 h at $4^{\circ}C$. The studies about thermal inactivation of D-hydroxyisovalerate dehydrogenase exhibit 209.2 kJ/M of activation enthalpy and 0.35 kJ/mol K of activation entropy.