Abstract:
:The kinetics of refolding of Escherichia coli dihydrofolate reductase (EC 1.5.1.3) have been examined upon dilution of unfolded enzyme in 4.5 M urea to 1.29 M urea in 0.02 M phosphate buffer (pH 7.2) at 10 degrees C. Changes in the intrinsic protein fluorescence on refolding are characterized by four phases. Based on changes in the amplitudes of these phases, as a consequence of quenching of the intrinsic fluorescence by ligands, it is possible to determine the step at which a ligand binds during the refolding process. The results show that either NADP or NADPH binds to the last species formed in a sequence involving three intermediates between the unfolded and native states. Dihydrofolate, on the other hand, binds during the formation of the second observed intermediate. When refolding is performed in the presence of methotrexate, an analogue of dihydrofolate, and NADPH, NADPH binds, as determined from changes in NADPH fluorescence, to the third observed intermediate rather than the last (fourth) species formed. Measurements of the recovery of enzymatic activity during refolding suggest that dihydrofolate also induces NADPH binding prior to the final observed folding phase. These results define more closely the formation of structural domains during the folding of dihydrofolate reductase.
journal_name
Proc Natl Acad Sci U S Aauthors
Frieden Cdoi
10.1073/pnas.87.12.4413subject
Has Abstractpub_date
1990-06-01 00:00:00pages
4413-6issue
12eissn
0027-8424issn
1091-6490journal_volume
87pub_type
杂志文章abstract::Tracheal antimicrobial peptide (TAP) is a member of the beta-defensin family of antibiotic peptides found in the tracheal mucosa of the cow. TAP gene expression in the bovine airway is inducible by lipopolysaccharide and inflammatory mediators, suggesting that it functions to protect the upper airway from infection. L...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.93.24.14118
更新日期:1996-11-26 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1998-10-27 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1983-05-01 00:00:00
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更新日期:2005-04-19 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1985-09-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1994-04-12 00:00:00
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更新日期:2010-06-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1977-02-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1993-03-15 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1991-09-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1991-02-15 00:00:00