Please wait, while we are loading the content...
Please wait, while we are loading the content...
| Content Provider | PubMed Central |
|---|---|
| Author | Petruska, J. Goodman, M. F. Boosalis, M. S. Sowers, L. C. Cheong, C. Tinoco, I. |
| Abstract | The relation between DNA polymerase fidelity and base pairing stability is investigated by using DNA primer-template duplexes that contain a common 9-base template sequence but have either correct (A.T) or incorrect (G.T, C.T, T.T) base pairs at the primer 3' terminus. Thermal melting and enzyme kinetic measurements are compared for each kind of terminus. Analysis of melting temperatures finds that differences between the free energy changes upon dissociation (delta delta Go) are only 0.2, 0.3, and 0.4 kcal.mol-1 (1 cal = 4.18 J) for terminal A.T compared to G.T, C.T, and T.T mispairs, respectively, at 37 degrees C. We show that enthalpy changes are directly correlated with entropy changes for normal and abnormal base pairs in DNA in aqueous solution and that delta delta Go values are small because of near cancellation of corresponding enthalpy and entropy components. The kinetics of elongating primer termini are measured with purified Drosophila DNA polymerase alpha. The matched A.T terminus is found to be extended approximately 200 times faster than a G.T mismatch and 1400 and 2500 times faster than C.T and T.T mismatches, respectively. Enzymatic discrimination against elongating mismatched termini is based mainly on Km rather than Vmax differences. From Km at 37 degrees C, we find delta delta Go values of 2.6-3.7 kcal.mol-1, about an order of magnitude greater than indicated by melting data. A similar measurement of nucleotide insertion kinetics has previously found rates of forming A.T base pairs to be 500 times greater than G.T mispairs and 20,000 times greater than C.T and T.T mispairs. Here also, Km differences are mainly responsible for discrimination and indicate even larger delta delta Go values (4.3-4.9 kcal.mol-1). Thus, free energy differences between correct and incorrect base pairs in the active site cleft of polymerase appear to be greater than 10 times as large as in aqueous medium. We explore the idea that a binding cleft that snugly fits correct base pairs and excludes water at the active site may amplify base-pair free energy differences by reducing entropy differences and increasing enthalpy differences sufficiently to account for nucleotide insertion and extension fidelity. |
| Starting Page | 6252 |
| File Format | |
| ISSN | 10916490 |
| e-ISSN | 10916490 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Issue Number | 17 |
| Volume Number | 85 |
| Language | English |
| Publisher Date | 1988-09-01 |
| Access Restriction | Open |
| Subject Keyword | Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Multidisciplinary |
National Digital Library of India (NDLI) is a virtual repository of learning resources which is not just a repository with search/browse facilities but provides a host of services for the learner community. It is sponsored and mentored by Ministry of Education, Government of India, through its National Mission on Education through Information and Communication Technology (NMEICT). Filtered and federated searching is employed to facilitate focused searching so that learners can find the right resource with least effort and in minimum time. NDLI provides user group-specific services such as Examination Preparatory for School and College students and job aspirants. Services for Researchers and general learners are also provided. NDLI is designed to hold content of any language and provides interface support for 10 most widely used Indian languages. It is built to provide support for all academic levels including researchers and life-long learners, all disciplines, all popular forms of access devices and differently-abled learners. It is designed to enable people to learn and prepare from best practices from all over the world and to facilitate researchers to perform inter-linked exploration from multiple sources. It is developed, operated and maintained from Indian Institute of Technology Kharagpur.
Learn more about this project from here.
NDLI is a conglomeration of freely available or institutionally contributed or donated or publisher managed contents. Almost all these contents are hosted and accessed from respective sources. The responsibility for authenticity, relevance, completeness, accuracy, reliability and suitability of these contents rests with the respective organization and NDLI has no responsibility or liability for these. Every effort is made to keep the NDLI portal up and running smoothly unless there are some unavoidable technical issues.
Ministry of Education, through its National Mission on Education through Information and Communication Technology (NMEICT), has sponsored and funded the National Digital Library of India (NDLI) project.
| Sl. | Authority | Responsibilities | Communication Details |
|---|---|---|---|
| 1 | Ministry of Education (GoI), Department of Higher Education |
Sanctioning Authority | https://www.education.gov.in/ict-initiatives |
| 2 | Indian Institute of Technology Kharagpur | Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project | https://www.iitkgp.ac.in |
| 3 | National Digital Library of India Office, Indian Institute of Technology Kharagpur | The administrative and infrastructural headquarters of the project | Dr. B. Sutradhar bsutra@ndl.gov.in |
| 4 | Project PI / Joint PI | Principal Investigator and Joint Principal Investigators of the project |
Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon |
| 5 | Website/Portal (Helpdesk) | Queries regarding NDLI and its services | support@ndl.gov.in |
| 6 | Contents and Copyright Issues | Queries related to content curation and copyright issues | content@ndl.gov.in |
| 7 | National Digital Library of India Club (NDLI Club) | Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach | clubsupport@ndl.gov.in |
| 8 | Digital Preservation Centre (DPC) | Assistance with digitizing and archiving copyright-free printed books | dpc@ndl.gov.in |
| 9 | IDR Setup or Support | Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops | idr@ndl.gov.in |
|
Loading...
|