• 미생물학회지
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• 제41권2호
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• pp.135-139
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• 2005

Monascus purpureue KCCM 60016으로부터 색소생성 이 우수한 변이주 P-57이 생성한 홍국색소의 항산화 활성을 조사하였다. 홍국색소는 chloroform에 아주 잘 추출되며, 특히 hexane에서는 황색색소가 특이적으로 높게 추출되었다. DPPH radical소거 효과는 hexane분획, chloroform 분획, ethyl acetate분획, butanol 분획, water 분획의 순으로 높게 나타났다. Xanthine oxidase저해효과는 hexane분획, chloroform분획, ethyl acetate 분획의 순으로 높게 나타났으며, hexane 분획물의 경우 5 ppm에서 $41.2\%$, 50 ppm에서 $82.4\%$로 높은 저해율을 보였으며, 저해기작은 비경쟁적 저해였다.

• BMB Reports
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• 제34권1호
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• pp.51-58
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• 2001

Attempts using in vitro and in vivo selection procedures have been made to search for hammerhead ribozymes that have higher activities than the wild-type ribozyme and also to determine whether other sequences might be possible in the catalytic core of the hammerhead ribozyme. Active sequences selected in the past conformed broadly to the consensus core sequence except at A9, and no sequences were associated with higher activity than that of the hammerhead with the consensus core, an indication that the consensus sequence derived from viruses and virusoids is probably the optimal sequence [Vaish et al. (1997) Biochemistry 36, 6495-6501]. Recently, during construction of ribozyme expression vectors, we isolated a mutant hammerhead ribozyme, with an insertion of G between A9 and G10.1, that appeared to show significant activity [Kawasaki et al. (1996) Nucleic Acids Res. 24, 3010-3016; Kawasaki et al. (1998) Nature 393, 284-289]. We, therefore, characterized kinetic properties of the G-inserted mutant ribozymes in terms of the NUX rule. We demonstrate that the NUX rule is basically applicable to the G-inserted ribozymes and, more importantly, one type of G-inserted ribozyme was very active with $k_{cat}$, value of $6.4\;min^{-1}$ in 50 mM Tris-HCl (pH 8.0) and 10 mM $MgCl_2$ at $37^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2549-2552
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• 2011

In this study, the kinetic properties of wild-type and C117D mutant H. influenzae MurA (Hi MurA), which catalyzes the first reaction in the biosynthetic pathway of the cell wall, were characterized. Purified recombinant Hi MurA was active at pH values ranging from pH 5.5 to pH 10, and its $K_m$ (UNAG), $K_m$ (PEP), and $k_{cat}$ values were measured to be 31 ${\mu}M$, 24 ${\mu}M$, and 210 $min^{-1}$, respectively. Hi MurA activity was effectively inhibited by fosfomycin with an $IC_{50}$ value of 60 ${\mu}M$. Hi MurA contains a cysteine residue (C117) at the loop region near the PEP binding, whereas MurA from fosfomycin resistant Mycobaterium tuberculosis or Chlamydia trachomatis contain an aspartate residue instead of the cysteine at the corresponding site. Aspartate substitution of Cys117 in Hi MurA shifted its optimum pH from 7.8 to 6.0. In addition, the $K_m$ values for UNAG and PEP were increased to 160 ${\mu}M$ and 150 ${\mu}M$, respectively, and the $k_{cat}$ value was significantly reduced to 41 $min^{-1}$. Furthermore, the C117D mutant form of Hi MurA was not inhibited by 1 mM fosfomycin. These results indicate that the Cys117 of Hi MurA is the binding site of fosfomycin and plays an important role in the fast turnover of the catalytic reaction.

• 한국미생물·생명공학회지
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• 제11권3호
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• pp.217-222
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• 1983

본 실험에서 G. fujkuroi I-892를 우수 균주로 선정한 후 자외선과 NTC를 처리하여, 지베렐린 생산성이 30%이상 증가된 변이주 G. fujkuroi G-471을 분리하였다. (178.6mg/$\ell$) 이 변이주에 적당한 최적 배지조성과 발효조건을 조사한 결과 saccharose 10%, ammoniun tartarate 50mM malt extract 1.0% KH$_2$PO$_4$, 0.5% MgSO$_4$0.5%, FeSO$_4$0.0002%,, 미량원소 0.002%(v/v)으로 나타났으며, 초기pH5.0. 통기량 1vvm 교반속도 400rpm의 발효조건에서 253mg/$\ell$가 생산되어 기존의 배양조건에서 보다 30%정도 생산성이 증가되었다. 발효액의 초기pH는 지베렐린 생산에 상당한 영향을 미쳤으며, 초기pH를 4.0으로 조절한 경우가 가장 좋은 생산성을 나타냈다.

• 농업과학연구
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• 제12권2호
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• pp.324-332
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• 1985

각종(各種) 시료(試料)로부터 1,573주(株)의 균주(菌株)를 분리(分離)하고 그 중에서 endo-polygalacturonase (Endo-PG) 활성이 강한 Aspergillus niger B-15를 선발하였다. 이어서 선정균주(選定菌株)에 자외선을 연차적(連次的)으로 조사(照射)하여 변이주(變異株) U-46을 얻었으며 친주(親株)와 변이주(變異株)의 균학적성질(菌學的性質)을 조사(調査)하고 변이주(變異株)의 효소생산조건(酵素生産條件)과 반응조건(反應條件)을 검토(檢討)하여 아래와 같은 결과를 얻었다. 1. 변이주(變異株) U-46은 친주(親株)보다 분생자두(分生子頭)의 크기가 작아지고 분생자병(分生子柄)의 길이가 짧아졌다. 2. 밀기울배지에서의 배양(培養)에 있어서 Endo-PG생산(生産)을 위한 최적조건(最適條件)은 친주(親株) B-15의 경우 밀기울에 대한 첨수량(添水量) 40%, 배양온도(培養溫度) $30{\sim}35^{\circ}C$였으나 변이주(變異株) U-46의 경우는 밀기울에 대한 첨수량(添水量) 60~70%, 배양온도(培養溫度) $35^{\circ}C$였다. 배양일수는 어느 것이나 2~3일간이 적당하였다. 3. 친주(親株)와 변이주(變異株)를 각각의 최적조건(最適條件)에서 배양(培養)할 경우 친주(親株) B-15의 Endo-PG에 비하여 변이주 U-46의 효소활성은 약 20배 높았다. 4. 밀기울배지(밀기울에 대한 첨수량(添水量) 60%)에 $35^{\circ}C$, 3일간 배양할 경우 변이주 U-46 은 친주(親株)에 비하여 Endo-PG 활성이 약 47배(倍)로, Exo-PG 활성은 약 18배로 증가되었으며 cellulase, ${\alpha}$-amylase 및 glucoamylase 활성도 증가되었다. 5. 밀기울에 $(NH_4)_2SO_4$을 1.2~1.5% 첨가(添加)한 배지에서 변이주(變異株) U-46의 Endo-PG 활성(活性)은 약 20% 증가되었다. 6. 변이주(變異株) U-46의 조효소액(粗酵素液)의 Endo-PG 반응(反應) 최적조건은 pH 4.0~4.5, $50^{\circ}C$이었다.

• 대한본초학회지
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• 제37권5호
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• pp.9-16
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• 2022

Objectives : The purpose of this study is to report that applying the genetic discrimination method to Pinelliae Tuber is suitable as a countermeasure for the limitations of morphological identification announced publicly in the Ministry of Food and Drug Safety(MFDS). Methods : Randomly selected fifty samples in Pinelliae Tuber imported from China were used for morphological and genetic identification. The morphological identification was applied method announced publicly by the MFDS. The traits of morphological identification were classified as Pinellia ternata, P. tripartita, Pinellia pedatisecta, and Typhonium flagelliforme, according to the formation of tuberous root and tuber morphology. The genetic identifications were conducted by Sequence Characterized Amplified Region(SCAR) marker and DNA barcoding analysis for cross-validation, respectively. SCAR marker was verified according to the presence or absence of amplicon through PCR amplification using species-specific primers. DNA barcoding analysis used sequence information of the matK region. Results : As a result of the morphological identification, 27 out of 50 samples were identified as original species 'P. ternata' of genuine 'Pinelliae Tuber', and 23 were identified as adulterant species 'P. pedatisecta'. Unlike this, the genetic identification was identified as the original species 'P. ternata' in all 50 samples in the SCAR marker and matK regional sequence analysis. Conclusions : Pinelliae Tuber of morphological mutant that can not be classified by morphological identification is imported from China. The SCAR marker would be used as accurate and efficient assays for species identification of the morphological mutant.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.452-460
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• 2016

Acid stress can affect the viability of probiotics, especially Bifidobacterium. This study aimed to improve the acid tolerance of Bifidobacterium longum BBMN68 using adaptive evolution. The stress response, and genomic differences of the parental strain and the variant strain were compared by acid stress. The highest acid-resistant mutant strain (BBMN68m) was isolated from more than 100 asexual lines, which were adaptive to the acid stress for 10^th, 20^th, 30^th, 40^th, and 50^th repeats, respectively. The variant strain showed a significant increase in acid tolerance under conditions of pH 2.5 for 2 h (from 7.92 to 4.44 log CFU/ml) compared with the wild-type strain (WT, from 7.87 to 0 log CFU/ml). The surface of the variant strain was also smoother. Comparative whole-genome analysis showed that the galactosyl transferase D gene (cpsD, bbmn68_1012), a key gene involved in exopolysaccharide (EPS) synthesis, was altered by two nucleotides in the mutant, causing alteration in amino acids, pI (from 8.94 to 9.19), and predicted protein structure. Meanwhile, cpsD expression and EPS production were also reduced in the variant strain (p < 0.05) compared with WT, and the exogenous WT-EPS in the variant strain reduced its acid-resistant ability. These results suggested EPS was related to acid responses of BBMN68.

• Journal of Microbiology
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• 제44권1호
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• pp.50-53
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• 2006

Cys-29 and Cys-251 of Streptomyces albus valine dehydrogenase(ValDH) were highly conserved in the corresponding region of $NAD(P)^+$-dependent amino acid dehydroganase sequences. To ascertain the functional role of these cysteine residues in S. albus ValDH, site-directed mutagenesis was performed to change each of the two residues to serine. Kinetic analyses of the enzymes mutated at Cys-29 and Cys-251 revealed that these residues are involved in catalysis. We also constructed mutant ValDH by substituting valine for leucine at 305 by site-directed mutagenesis. This residue was chosen, because it has been proposed to be important for substrate discrimination by phenylalanine dehydrogenase (PheDH) and leucine dehydrogenase (LeuDH). Kinetic analysis of the V305L mutant enzyme revealed that it is involved in the substrate binding site. However it displayed less activity than the wild type enzyme toward all aliphatic and aromatic amino acids tested.

• 한국미생물·생명공학회지
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• 제19권1호
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• pp.1-7
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• 1991

A bacterial strain No.71, which produced alkaline protease, was isolated from soil and identified to the genus Bacillus. With the successive mutation, a mutant strain No. M-71, having high alkaline protease productivity, was obtanined from the parental strain No 71. Alkaline protease productivity of mutant strain No. M-71 was about 50 times as much as that of the parental strain No.71. The enzyme preparations showed strong activities toward casein, the optimum pH being 11.0 and the optimum temperature about $55^{\circ}C$.

• BMB Reports
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• 제50권7호
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• pp.373-378
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• 2017

The Jun activation-domain binding protein 1 (Jab1) induces p53 nuclear export and cytoplasmic degradation, but the underlying mechanism is poorly understood. Here, we show that phosphorylation at the threonine 155 residue is essential for Jab1-mediated p53 nuclear export. Jab1 stimulated phosphorylation of p53 at T155 was inhibited by curcumin, an inhibitor of COP9 signalosome (CSN)-associated kinases. The T155E mutant, which mimics phosphorylated p53, exhibited spontaneous cytoplasmic localization in the absence of Jab1. This process was prevented by leptinomycin B (LMB), but not by curcumin. The substitution of threonine 155 for valine (T155V) abrogated Jab1-mediated p53 nuclear export, indicating that phosphorylation at this site is essential for Jab1-mediated regulation of p53. Although T155E can be localized in the cytoplasm in the absence of Mdm2, the translocation of T155E was significantly enhanced by ectopic Hdm2 expression. Our data suggests that Jab1-mediated phosphorylation of p53 at Thr155 residue mediates nuclear export of p53.