Please wait, while we are loading the content...
Please wait, while we are loading the content...
| Content Provider | PubMed Central |
|---|---|
| Author | Gráf, L. Jancsó, A. Szilágyi, L. Hegyi, G. Pintér, K. Náray-szabó, G. Hepp, J. Medzihradszky, K. Rutter, W. J. |
| Abstract | The aspartic residue (Asp-189) at the base of the substrate-binding pocket of trypsin was replaced by serine (present in a similar position in chymotrypsin) through site-directed mutagenesis. The wild-type (with Asp-189 in the mature trypsin sequence) and mutant (Ser-189) trypsinogens were expressed in Escherichia coli, purified to homogeneity, activated by enterokinase, and tested with a series of fluorogenic tetrapeptide substrates with the general formula succinyl-Ala-Ala-Pro-Xaa-AMC, where AMC is 7-amino-4-methyl-coumarin and Xaa is Lys, Arg, Tyr, Phe, Leu, or Trp. As compared to [Asp189]trypsin, the activity of [Ser189]trypsin on lysyl and arginyl substrates decreased by about 5 orders of magnitude while its Km values increased only 2- to 6-fold. In contrast, [Ser189]trypsin was 10-50 times more active on the less preferred, chymotrypsin-type substrates (tyrosyl, phenylalanyl, leucyl, and tryptophanyl). The activity of [Ser189]trypsin on lysyl substrate was about 100-fold greater at pH 10.5 than at pH 7.0, indicating that the unprotonated lysine is preferred. Assuming the reaction mechanisms of the wild-type and mutant enzymes to be the same, we calculated the changes in the transition-state energies for various enzyme-substrate pairs to reflect electrostatic and hydrogen-bond interactions. The relative binding energies (E) in the transition state are as follows: EII greater than EPP greater than EPA greater than EIP approximately equal to EIA, where I = ionic, P = nonionic but polar, and A = apolar residues in the binding pocket. These side-chain interactions become prominent during the transition of the Michaelis complex to the tetrahedral transition-state complex. |
| Starting Page | 4961 |
| File Format | |
| ISSN | 10916490 |
| e-ISSN | 10916490 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Issue Number | 14 |
| Volume Number | 85 |
| Language | English |
| Publisher Date | 1988-07-01 |
| 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...
|