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최석정,양철학 ( Suk Jung Choi,Chul Hak Yang ) 생화학분자생물학회 1990 BMB Reports Vol.23 No.4
A spectrophotometric assay method for hydrogenase was studied. The sample solution was flushed with nitrogen or hydrogen to remove oxygen, and the reaction started. At the end of the reaction, 2`,3`,5`-tiphenyl tetrazolium chloride was reduced with reduced methyl viologen, and the concentration was determined by monitoring the absorbance at 600 nm. The absorbance increased linearly with increasing amount of enzyme in both cases of uptake and evolution assay. Alternatively, the concentration of reduced MV can be measured directly with autofill or microflow device which avoids a contact of the solution with air. This method also showed good results.
최석정,양철학 ( Suk Jung Choi,Chul Hak Yang ) 생화학분자생물학회 1990 BMB Reports Vol.23 No.3
A set of hydrogenase-defective E. coli mutant strains have been isolated. Among them, three mutants, E. coli HD24, 43, and 50, were complemented with pHY1 previously reported (Oh et al., 1987). Another mutant strain, HD6, was transformed with E. coli chromosomal DNA library and a plasmid, pHY3, was isolated which restored hydrogenase activity in this strain. This plasmid was proved to contain two genes essential for hydrogenase activity by the complementation test of various mutants with each fragment of the insert. The two genes are contained in 2.1 kb Sall fragment of pHY3-insert. It seems that this fragment also has its own promoter. When it was expressed under the control of tac promoter, it gave two polypeptides of molecular masses, 31 and 43 kDa with a cellular content of about 10 percent. However, their increase did not correlated with the increase of hydrogenase activity. That is, they are essential components for hydrogenase activity but not sufficient.
Cloning and Overexpression of Escherichia Coli Hydrogenase Operon
최석정,양철학,Choi, Suk-Jung,Yang, Chul-Hak Korean Society for Biochemistry and Molecular Biol 1990 한국생화학회지 Vol.23 No.3
A set of hydrogenase-defective E. coli mutant strains have been isolated. Among them, three mutants, E. coli HD24, 43, and 50, were complemented with pHY1 previously reported (Oh et al., 1987). Another mutant strain, HD6, was transformed with E. coli chromosomal DNA library and a plasmid, pHY3, was isolated which restored hydrogenase activity in this strain. This plasmid was proved to contain two genes essential for hydrogenase activity by the complementation test of various mutants with each fragment of the insert. The two genes are contained in 2.1 kb SalI fragment of pHY3-insert. It seems that this fragment also has its own promoter. When it was expressed under the control of tac promoter, it gave two polypeptides of molecular masses, 31 and 43 kDa with a cellular content of about 10 percent. However, their increase did not correlated with the increase of hydrogenase activity. That is, they are essential components for hydrogenase activity but not sufficient. 수소발생효소의 활성이 결핍된 일련의 대장균 돌연변이체를 얻었다. 그 중에, HD24, 43 그리고 50의 세 돌연변이체는 전에 보고되었던 plasmid, pHY1에 의해 보완되었다. 다른 돌연변이체인 HD6를 대장균 염색체 DNA library로 형질변환 시킨 후, 이 돌연변이체의 수소발생효소 활성을 회복시키는 plasmid, pHY3를 얻었다. 이 plasmid는, 그 insert의 각 fragment를 이용한 보완실험에 의해, 수소 발생효소에 필수적인 두 개의 유전자를 갖고 있는 것으로 밝혀졌다. 그 두 유전자는 2.1 kb인 SalI-fragment에 포함되어 있었다. 또한 이 조각은 그 자체의 promoter를 갖고 있는 것으로 생각되며, tac promoter의 조절하에 형질발현 시켰을 때, 그 분자량이 각각 31과 43 kDa인 두 폴리펩티드를 만들었고, 그 세포내 함량은 대략 10퍼센트 정도였다. 그러나, 그 두 폴리펩티드의 양의 증가로 인해 수소발생효소 활성이 증가하지는 않는 것으로 보아, 그들은 효소활성에 필수적이기는 하나, 충분하지는 않은 것으로 생각된다.
Identification of a Deoxyribonuclease I Inhibitor from a Phage-Peptide Library
최석정,Jeffery J. Sperinde,Francis C. Szoka Jr. 한국분자세포생물학회 2005 Molecules and cells Vol.19 No.1
Deoxyribonuclease I (DNase I) is a divalent cation de-pendent endonuclease and thought to be a significant barrier to effective gene delivery. The only known DNase I-specific inhibitor is monomeric actin which acts by forming a 1:1 complex with DNase I. Its use, however, is restricted because of tendency to polymer-ize under certain conditions. We screened two random phage peptide libraries of complexity 108 and 109 for DNase I binders as candidates for DNase I inhibitors. A number of DNase I-binding peptide sequences were identified. When these peptides were expressed as fu-sion proteins with Escherichia coli maltose binding protein, they inhibited the actin-DNase I interaction (IC50 = 0.10.7 M) and DNA degradation by DNase I (IC50 = 0.88 M). Plasmid protection activity in the presence of DNase I was also observed with the fusion proteins. These peptides have the potential to be a use-ful adjuvant for gene therapy using naked DNA