Abstract
The mechanism of type IB topoisomerase-mediated DNA relaxation was studied by modification of vaccinia topoisomerase I at the active site tyrosine (position 274) with several tyrosine analogues. These analogues had varied steric, electronic, and stereochemical features to permit assessment of those structural elements required to support topoisomerase function. Eleven tyrosine analogues were successfully incorporated into the active site of vaccinia topoisomerase I. It was found that only tyrosine analogues having the phenolic -OH group in the normal position relative to the protein backbone were active. Modifications that replaced the nucleophilic tyrosine OH (pKa ≈ = 10.0) group with NH2 (pKa 4.6), SH (pKa ≈ 7.0), or I groups or that changed the orientation of the nucleophilic OH group essentially eliminated topoisomerase I function. For the active analogues, the electronic effects and H-bonding characteristics of substituents in the meta-position of the aromatic ring may be important in modulating topoisomerase I function. The pH profile for the functional analogues revealed a small shift toward lower pH when compared with wild-type topoisomerase I.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3321-3331 |
| Number of pages | 11 |
| Journal | Journal of the American Chemical Society |
| Volume | 127 |
| Issue number | 10 |
| DOIs | |
| State | Published - Mar 16 2005 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Chemistry(all)
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Analogues of vaccinia virus DNA topoisomerase I modified at the active site tyrosine. / Gao, Rong; Zhang, Yi; Choudhury, Ambar K.; Dedkova, Larisa; Hecht, Sidney.
In: Journal of the American Chemical Society, Vol. 127, No. 10, 16.03.2005, p. 3321-3331.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Analogues of vaccinia virus DNA topoisomerase I modified at the active site tyrosine
AU - Gao, Rong
AU - Zhang, Yi
AU - Choudhury, Ambar K.
AU - Dedkova, Larisa
AU - Hecht, Sidney
PY - 2005/3/16
Y1 - 2005/3/16
N2 - The mechanism of type IB topoisomerase-mediated DNA relaxation was studied by modification of vaccinia topoisomerase I at the active site tyrosine (position 274) with several tyrosine analogues. These analogues had varied steric, electronic, and stereochemical features to permit assessment of those structural elements required to support topoisomerase function. Eleven tyrosine analogues were successfully incorporated into the active site of vaccinia topoisomerase I. It was found that only tyrosine analogues having the phenolic -OH group in the normal position relative to the protein backbone were active. Modifications that replaced the nucleophilic tyrosine OH (pKa ≈ = 10.0) group with NH2 (pKa 4.6), SH (pKa ≈ 7.0), or I groups or that changed the orientation of the nucleophilic OH group essentially eliminated topoisomerase I function. For the active analogues, the electronic effects and H-bonding characteristics of substituents in the meta-position of the aromatic ring may be important in modulating topoisomerase I function. The pH profile for the functional analogues revealed a small shift toward lower pH when compared with wild-type topoisomerase I.
AB - The mechanism of type IB topoisomerase-mediated DNA relaxation was studied by modification of vaccinia topoisomerase I at the active site tyrosine (position 274) with several tyrosine analogues. These analogues had varied steric, electronic, and stereochemical features to permit assessment of those structural elements required to support topoisomerase function. Eleven tyrosine analogues were successfully incorporated into the active site of vaccinia topoisomerase I. It was found that only tyrosine analogues having the phenolic -OH group in the normal position relative to the protein backbone were active. Modifications that replaced the nucleophilic tyrosine OH (pKa ≈ = 10.0) group with NH2 (pKa 4.6), SH (pKa ≈ 7.0), or I groups or that changed the orientation of the nucleophilic OH group essentially eliminated topoisomerase I function. For the active analogues, the electronic effects and H-bonding characteristics of substituents in the meta-position of the aromatic ring may be important in modulating topoisomerase I function. The pH profile for the functional analogues revealed a small shift toward lower pH when compared with wild-type topoisomerase I.
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UR - http://www.scopus.com/inward/citedby.url?scp=14944354815&partnerID=8YFLogxK
U2 - 10.1021/ja044182z
DO - 10.1021/ja044182z
M3 - Article
C2 - 15755148
AN - SCOPUS:14944354815
VL - 127
SP - 3321
EP - 3331
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 10
ER -