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V. Sasisekharan

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V. Sasisekharan
Born(1933-06-28)28 June 1933(age 91)
India
NationalityIndian
Alma mater
Known forConformation ofbiopolymers
Awards1978Shanti Swarup Bhatnagar Prize
1981 FICCI Award
1983INSAJ. C. Bose Medal
1985 Hari Om Ashram J. C. Bose Award
1987 Watumull Honor Summus Medal
1989Om Prakash Bhasin Award
Scientific career
Fields
Institutions

Viswanathan Sasisekharan(born 1933) is an Indian biophysicist known for his work on the structure and conformation ofbiopolymers.He introduced the use of torsion angles to describepolypeptideandproteinconformation, a central principle of the (φ, ψ) plot (later known as theRamachandran plot).[1][2][3]Additionally, he was the first to introduce alternative models of DNA structure that provided insights beyond the standarddouble helixmodel.[4][5][6]For his contributions to the biological sciences, he was awarded theShanti Swarup Bhatnagar Prize for Science and Technology,one of India’s highest science awards, in 1978.[7]

Education and career

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V. Sasisekharan was born on 28 June 1933 in the South Indian state ofTamil Nadu.He earned his Ph.D. from theUniversity of Madrasin 1959.[8]From 1959–1963, he was a lecturer at the University of Madras, and from 1963–1964, he was a visiting scientist at theNational Institutes of Health(NIDDK).[8]In 1964, he joined the University of Madras as a reader at the Centre of Advanced Study in Physics and served as a professor and administrative head of the Department of Physics from 1968–1970 and 1971–1972.[8]He was a visiting professor atPrinceton Universityat their Frick Chemical Laboratory from 1970–1971.[8]

In 1972, Sasisekharan moved to theIndian Institute of Science(IISc) Bangalore, where he served as the professor and chairman of theMolecular Biophysics Unit;chairman of the Division of Chemical and Biological Sciences; and dean of the Faculty of Science. He was a visiting professor at theUniversity of Chicago,and was an adjunct professor at the School of Pharmacy,University of California, San Francisco.[9]

Research

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As a graduate student, Sasisekharan studied the structure ofcollagenchains and developed methods to generate the coordinates of constituent atoms of peptides with a high degree of accuracy.[10]Using this approach and published crystal structures, he identified allowable non-bonded distances between atoms of consecutive amino acids.[1]For the first time, he used torsion angles to describe the conformation of polypeptide chains and determined the allowable regions for the two torsion angles (originally named φ and φ’, later as φ and ψ).[1]This formed the basis for the (φ, ψ) plot, which was expanded and later became known as theRamachandran plot.[2][11]While Sasisekharan calculated these allowable regions using only a few available proteincrystal structuresat the time, the (φ, ψ) plot has remained nearly unchanged for 60 years.[3]

Later in his career, part of Sasisekharan’s work focused on the structure of nucleic acids. He and his coworkers demonstrated that the available experimental results were compatible with both right- and left-handed double helical models for DNA. They also showed the enormous degree of conformational flexibility in the basic units of DNA and highlighted the concept of sequence specific conformation and DNA conformational polymorphism. In addition, they proposed a structure of DNA consisting of alternating left- and right-handed helical segments, known as the side-by-side (S-B-S) model, an alternative to the right-handed double helix model.[4][5][6]The S-B-S model offered greater structural flexibility that could facilitate the uncoiling of the double helix without topological rearrangement during replication or other processes.[4][5][6][12]

His son,Ram Sasisekharan,is a bioengineer[13][14]and a co-author of some of his publications.[15]

Awards and honors

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TheCouncil of Scientific and Industrial Researchawarded Sasisekharan theShanti Swarup Bhatnagar Prize(one of India’s highest science awards) in 1978 for his contributions to the fields of biopolymers and DNA structure analysis.[7]He received the FICCI Award of theFederation of Indian Chamber of Commerce and Industryin 1981, and theIndian National Science Academyawarded him the Jagadis Chandra Bose Medal in 1983.[16]In 1985, he held the ASTRA chair in Biological Sciences at theIndian Institute of Scienceand received the Jagdish Chandra Bose Award for Research in Life Sciences from theUniversity Grants Commission of India.[8]He was awarded the Honor Summus Medal of the Watunull Foundation in 1987 and was selected as a Fogarty Scholar-In-Residence at theNational Institutes of Healthin 1988. He received theOm Prakash Bhasin Awardin 1989.[17]Sasisekharan was elected fellow of theIndian Academy of Sciencesin 1969[18]and fellow of theIndian National Science Academyin 1980.[8]

See also

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References

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  1. ^abcSasisekharan, V (1962). Ramanathan, N (ed.).Stereochemical Criteria for Polypeptide and Protein Structures.New York: John Wiley. pp. 39–77.{{cite book}}:|work=ignored (help)
  2. ^abRamachandran, G. N.; Ramakrishnan, C.; Sasisekharan, V. (1963)."Stereochemistry of polypeptide chain configurations".Journal of Molecular Biology.7:95–99.doi:10.1016/s0022-2836(63)80023-6.ISSN0022-2836.PMID13990617.
  3. ^abHollingsworth, Scott A.; Karplus, P. Andrew (1 October 2010)."A fresh look at the Ramachandran plot and the occurrence of standard structures in proteins".BioMolecular Concepts.1(3–4): 271–283.doi:10.1515/bmc.2010.022.ISSN1868-503X.PMC3061398.PMID21436958.
  4. ^abcSasisekharan, V; Pattabiraman, N (1976)."Double stranded polynucleotides: two typical alternative conformations for nucleic acids"(PDF).Current Science.45:779–783. Archived fromthe original(PDF)on 13 December 2019.Retrieved21 June2020.
  5. ^abcSasisekharan, V.; Pattabiraman, N. (1978)."Structure of DNA predicted from stereochemistry of nucleoside derivatives".Nature.275(5676): 159–162.Bibcode:1978Natur.275..159S.doi:10.1038/275159a0.ISSN0028-0836.PMID692688.S2CID4145327.
  6. ^abcSasisekharan, V.; Pattabiraman, N.; Gupta, G. (1 September 1978)."Some implications of an alternative structure for DNA".Proceedings of the National Academy of Sciences.75(9): 4092–4096.Bibcode:1978PNAS...75.4092S.doi:10.1073/pnas.75.9.4092.ISSN0027-8424.PMC336057.PMID279899.
  7. ^ab"View Bhatnagar Awardees".Shanti Swarup Bhatnagar Prize. 2016.Retrieved19 September2016.
  8. ^abcdef"Indian Fellow - Sasisekharan".Indian National Science Academy. 2016.Retrieved23 September2016.
  9. ^University of California, San Francisco. School of Pharmacy (1979).UCSF School of Pharmacy Bulletin.The University. pp. 4–.
  10. ^Sasisekharan, V (1959). "Structure of collagen and related compounds".PhD Thesis, University of Madras.
  11. ^Ramachandran, G.N.; Sasisekharan, V. (1968),"Conformation of Polypeptides and Proteins",Advances in Protein Chemistry,23,Elsevier: 283–437,doi:10.1016/s0065-3233(08)60402-7,ISBN978-0-12-034223-5,PMID4882249,retrieved21 June2020
  12. ^Bansal, Manju (2003)."DNA structure: Revisiting the Watson–Crick double helix".Current Science.85(11): 1556–1563.ISSN0011-3891.JSTOR24110017.
  13. ^Jayan, T.V. (10 June 2013)."Sugary route to success".The Telegraph. Archived fromthe originalon 15 June 2013.Retrieved26 April2018.
  14. ^"Ram Sasisekharan, PhD | MIT Department of Biological Engineering".be.mit.edu.Retrieved21 June2020.
  15. ^Fundamentals of Advanced Omics Technologies: From Genes to Metabolites.Newnes. 14 February 2014. pp. 280–.ISBN978-0-444-62670-7.
  16. ^"The Jagadis Chandra Bose Medal".INSA. 2016. Archived fromthe originalon 16 September 2016.Retrieved24 September2016.
  17. ^"OPB Awards".Om Prakash Bhasin Foundation. 2014. Archived fromthe originalon 6 November 2020.Retrieved23 September2016.
  18. ^"Fellow Profile".Indian Academy of Sciences. 2016.Retrieved24 September2016.
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