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1.
Yeon‐Sook Kim Yeon‐Joo Choi Kyung‐Min Lee Kyu‐Joong Ahn Heung‐Chul Kim Terry Klein Ju Jiang Allen Richards Kyung‐Hee Park Won‐Jong Jang 《Microbiology and immunology》2017,61(7):258-263
2.
A novel gene, sps2, detected in mouse embryo at the early stages of development has been identified as an analog of the E. coli selenophosphate synthetase gene. Unlike the E. coli enzyme, the presence of selenocysteine in the mouse enzyme is indicated by a TGA codon in the open reading frame of the cDNA. Using an N-FLAG monoclonal antibody, it was shown that the full length N-FLAG-sps2 gene product was expressed in COS-7 cells. To investigate the biological activity of the sps2 gene product in vivo, the mutated sps2 gene, which contains cysteine in the place of the TGA encoded selenocysteine in the wild type, was expressed in the E. coli selD deficient mutant, MB08. Like the E. coli wild type selD gene, the mutant sps2 gene complemented the selD mutation. However, replacement of Cys with either Ala, Ser, or Thr resulted in a loss of ability to complement the selD mutation. The SPS2-CYS protein expressed in E. coli was purified and its catalytic activity was determined. The Km value for ATP was 0.75 mM and Vmax was 9.23 nmole/min/mg protein. These results confirm that the mouse embryonic sps2 gene encodes an eukaryotic selenophosphate synthetase, and that availability of selenophosphate as a selenium donor compound is widespread. 相似文献
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G Y Song X G Zheng Y Kim Y J You D E Sok B Z Ahn 《Bioorganic & medicinal chemistry letters》1999,9(16):2407-2412
6-(1-Hydroxyalkyl)-5,8-dimethoxy-1,4-naphthoquinones, expressing a higher reactivity in conjugation with glutathione, showed a greater potency in the inhibition of DNA topoisomerase-I and the cytotoxicity against L1210 cells than 2-(1-hydroxyalkyl)-DMNQ derivatives, implying the participation of electrophilic arylation in the bioactivities. In further study 6-(1-Hydroxyalkyl)-5,8-dimethoxy-1,4-naphthoquinones with an alkyl group of shorter chain length (C2-C6) exerted a greater bioactivities than those with longer chain length(>C6). 相似文献
6.
Ha Na Seo Bo Young Jeon Hung Thuan Tran Dae Hee Ahn Doo Hyun Park 《Biotechnology and Bioprocess Engineering》2008,13(2):224-231
Saccharomyces sp. SK0704 (further defined as SK0704) isolated from long-term-ripening kimchi was identified by a biochemical method with
an API kit; its physiology was found to be very similar to that of S. cerevisiae ATCC 26603 (further defined as ATCC 26603), except in terms of starch utilization. SK0704 did not excrete extracellular glucoamylase,
but utilized starch as a sole carbon source under only aerobic conditions. Crude enzyme excreted from SK0704 catalyzed the
saccharification of starch to glucose, but ATCC 26603 did not. The PCR product obtained using the chromosomal DNA of SK0704
and the primers designed on the basis of the extracellular glucoamylase-coding gene of S. diastaticus was homologous with the intracellular sporulation-specific glucoamylase of S. cerevisiae. SDS-PAGE pattern of soluble protein extracted from yeast cells grown on glucose was greatly different from that on starch.
From these results, we proposed that the SK0704 may have a specific physiological function for starch catabolism such as membrane
transport system and intracellular sac-charification of starch. 相似文献
7.
Theoretical compensation after anterior cruciate ligament (ACL) tear could cause quadriceps weakness and hamstring activation, preventing anterior tibial subluxation and affecting the expected hamstring-to-quadriceps ratio. Although quadriceps weakness often occurs after ACL tears, it remains unclear whether hamstring strength and hamstring-to-quadriceps ratio increase in ACL deficient knees. This meta-analysis compared the isokinetic muscle strength of quadriceps and hamstring muscles, and the hamstring-to-quadriceps ratio, of the injured and injured limbs of patients with ACL tears. This meta-analysis included all studies comparing isokinetic thigh muscle strengths and hamstring-to-quadriceps ratio in the injured and uninjured legs of patients with ACL tear, without or before surgery. Thirteen studies were included in the meta-analysis. Quadriceps and hamstring strengths were 22.3 N∙m (95% CI: 15.2 to 29.3 N∙m; P<0.001) and 7.4 N∙m (95% CI: 4.3 to 10.5 N∙m; P<0.001) lower, respectively, on the injured than on the uninjured side. The mean hamstring-to-quadriceps ratio was 4% greater in ACL deficient than in uninjured limbs (95% CI: 1.7% to 6.3%; P<0.001). Conclusively, Decreases were observed in both the quadriceps and hamstring muscles of patients with ACL tear, with the decrease in quadriceps strength being 3-fold greater. These uneven reductions slightly increase the hamstring-to-quadriceps ratio in ACL deficient knees. 相似文献
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Jae-Il Ahn In-Keun Jang Young-Kwon Seo Hee-Hoon Yoon Yeon-Ho Shin Jae-Chan Kim Kye-Yong Song Eun-Kyung Yang Jung-Keug Park 《Biotechnology and Bioprocess Engineering》2008,13(3):279-287
Herein, we reconstructed a rabbit corneal epithelium on a lyophilized amniotic membrane (LAM) using a modified version of
two Teflon rings (the Ahn’s supporter). We compared the corneal epithelial cells we had differentiated in vitro using air-liquid interface (6 days, 12 days) and submerged (6 days, 12 days) cultures and followed a six-day tilting dynamic
air-liquid interface culture with a six-day tilting submerged culture. We characterized the reconstructed corneal epithelium
using digital photography, histological imaging, and transmission electron microscopy. The reconstructed corneal epithelium
created under air-liquid interface culture exhibited a healthier basal corneal epithelial layer than that created under submerged
culture. The reconstructed corneal epithelium on the LAM that was produced using the tilting dymanic culture exhibited a healthy
basal layer. We therefore proposed that tilting submerged culture not only supplied nutrients from the medium to the corneal
epithelial cells on the LAM, but it also removed the horny layer in the upper part of the reconstructed corneal epithelium,
presumably by mimicking the effects of blinking. This study demonstrated that corneal epithelium reconstruction on a LAM using
a tilting submerged culture after a tilting air-liquid interface culture may be useful not only for allogeneic or autologous
transplantation, but also for in vitro toxicological test kits. 相似文献
10.
Hyuk-Sung Kwon Eunyong Chung Junse Oh Chang-Ha Lee Ik-Sung Ahn 《Biotechnology and Bioprocess Engineering》2008,13(1):108-114
Manganese peroxidase (MnP) is a key enzyme involved in the lignolysis of white-rot fungi. The purpose of this study is to
investigate the effect of immobilization and culture conditions on MnP production in cultures of Phanerochaete chrysosporium grown on polyurethane foam. Higher concentrations of foam and lower levels of spore inoculums resulted in the formation of
scattered mycelial pellets, increased autolysis of chlamydospore-like cells (a reservoir of MnP), and a higher activity of
MnP. Even though MnP was a secondary metabolite, the addition of 5 times more glucose and diammonium tartrate, as carbon and
nitrogen sources, resulted in a 4 fold increase in the dry cell mass. However, MnP activity decreased under these conditions
to less than half, due to the formation of increasingly dense pellets and the inhibited lysis of chlamydospore-like cells. 相似文献