Anil Kumar 25 June 1941 – 9 November, 2024
ISMAR mourns the passing of Prof. Anil Kumar on November 9, 2024, at the age of 83 after a brief illness.
Anil had worked as a young research associate with Richard R. Ernst and Kurt Wüthrich, where he performed the first NOESY experiment on a protein, ... also the first 2D-FT-MRI experiment. [He was] one of the most outstanding Indian NMR spectroscopists, and important contributor to quantum information processing by NMR. And owner of the most infectious chuckle in NMR (Malcolm Levitt).
Anil was a professor at the Indian Institute of Science in Bengaluru. Among his many recognitions are the Sir C.V. Raman Medal and the Goyal Award in Chemistry by the Indian Chemical Society. He was a fellow of the Indian National Science Academy and of ISMAR, and friend to many of us.
We miss him deeply.
The following tributes and remembrances are from Anil's former Swiss colleagues Profs. Kurt Wüthrich and Gerhard Wagner as well as his Indian colleagues Profs. Suryaprakash Nagarajarao, K .V. Ramanathan, and P.K. Madhu.
Tribute by Kurt Wüthrich and Gerhard Wagner
With the passing of Professor Anil Kumar the Swiss NMR community has lost a very special scientific colleague and a dear friend. We recall here a particularly memorable visit in Switzerland.
Anil Kumar spent a sabbatical year from August 1979 to July 1980 as an “Akademischer Gast” at the ETH Zürich, where he joined the collaboration project of Richard R. Ernst and Kurt Wüthrich on the development of two-dimensional NMR for studies of biological macromolecules in solution. This project had been started in November 1976, with Kuniaki Nagayama located in the space of the Wüthrich group at the ETH Hoenggerberg campus and Peter Bachmann located in the space of the Ernst group at the downtown ETH campus. Kuniaki and Peter had by 1979 written the software for 2D NMR spectroscopy, and established protocols for recording homonuclear 2D J-resolved, SECSY and COSY data sets of proteins. Peter Bachmann left the project in April 1979. Kuniaki Nagayama continued to optimize the correlation experiments specifically, to overcome limitations of the available memory and disc space. Anil Kumar inherited Kuniaki Nagayama’s position in the joint project and his one-year stay with us was tremendously successful.
Roots of this success are manyfold: Anil Kumar was one of the highly gifted scientists working on NMR. Anil had in the mid-70s been a postdoctoral fellow in Richard Ernst’s group, when they worked on the initial 2D NMR experiments with small molecules and on basics of magnetic resonance imaging. In 1979, Anil and Kuniaki overlapped in the Wüthrich laboratory for three months, so that Anil could get thoroughly introduced into the practice of 2D NMR with proteins. In several long evening discussions on the possibilities of adding 2D NOE experiments to our arsenal, we underestimated the sensitivity that could be achieved when working with macromolecules. As a consequence, Anil Kumar was encouraged to use the time period from December 23, 1979 to January 3, 1980 for a single 2D NOE experiment on our 360 MHz NMR spectrometer with a highly concentrated solution of the protein BPTI. The result was a 2D NOESY map of superb quality. Anil then joined forces with Gerhard Wagner to combine the power of the 2D NOE experiments with Gerhard’s long-standing experience from one-dimensional NOE experiments with proteins. Gerhard remembers this time in the following paragraphs.
I, Gerhard Wagner, was at the time an “Oberassistent” in the Wüthrich laboratory and had the pleasure to host Anil Kumar during his 1979/1980 sabbatical in my office for a couple of weeks. From his earlier time in the Ernst lab, Anil had a deep understanding of the principles of 2D NMR. He realized that this principle could also be applied for 2D NOE experiments. Luckily, we had a highly soluble protein available, the basic pancreatic trypsin inhibitor, BPTI, which we could concentrate up to 20 mM or more. Furthermore, we had realized that when using short (truncated) irradiation times, small numbers of short distance contacts could be obtained, which allowed nearly complete backbone assignments for BPTI by avoiding problems of spin diffusion. We had built a plastic model of BPTI based on the known crystal structure. Studying this model we realized that the shortest distances were across the peptide bonds from the amide protons to the preceding alpha protons. Thus, applying short irradiating times to individual resolved amide signals with 1D NMR experiments yielded a large fraction of connectivities across the peptide bonds. Spin decoupling yielded the intra-residue connections. However, this was at a loss for many of the overlapping signals that could not be assigned with 1D NOE or spin-decoupling experiments. Moreover, the water signal had to be saturated if amides were not slowly exchanging, which prevented to use the decoupler for selectively saturating amides to build up NOEs.
These limitations were overcome when Anil introduced the 2D NOE (NOESY) experiment in our lab where the selective saturations of proton signals were obtained with the three-pulse exchange-spectroscopy sequence. The decoupler was not needed for creating NOEs and was available for water saturation for assigning also protein signals with rapidly exchanging amides. As the initial 1D NOE experiments took much instrument time, irradiating many signals one after the other, it was not clear how sensitive the proposed 2D NOE would take. Thus, Anil was given our 360 MHz instrument over the long winter holiday break. Fortunately, the NOESY experiment was significantly more sensitive than expected and has since then become key for many biological NMR experiments, which was key for determine protein structures in solution.
Tribute by Suryaprakash Nagarajarao, K .V. Ramanathan and P.K. Madhu
Prof. Anil Kumar's contributions to nuclear magnetic resonance spanned a wide range. These include relaxation, cross-correlation, strong-coupling effects in multidimensional spectroscopy, cross-polarisation dynamics and suppression of sidebands in solid-state NMR, transition-selective pulses, nuclear quadrupolar resonance, and NMR quantum information and computing. Anil had a wonderful insight into the physics of various concepts in magnetic resonance and he was well noted for teaching various graduate-level courses that included NMR and Quantum Mechanics.
Prof. Anil Kumar obtained his Master’s degree from Agra University in the year 1961 and PhD degree in 1969 from the Indian Institute of Technology, Kanpur, under the supervision of Prof. B.D.N. Rao. He did his Post-doctoral research in the United States at the Georgia Institute of Technology with Prof. Sydney Gordon and at the University of North Carolina with Prof. Charles Johnson. He then moved to the laboratory of Prof. R.R. Ernst at ETH, Zurich where he performed the first 2D Fourier imaging experiment. He was also the first one to observe transient oscillations in cross-polarisation dynamics in solids. Anil returned to India and joined Indian Institute of Science, Bangalore as a Faculty member in January 1977. Here he started to work on further developments in two-dimensional NMR spectroscopy. He returned to Zurich for the academic year 1979-80, in a joint project of Prof. Ernst and Prof. Wuthrich. During this period, he was the first one to perform the two-dimensional Nuclear Overhauser Effect experiment, popularly known as NOESY in a protein, which opened the field for the determination of three-dimensional structures of biomolecules in solution by NMR. In his laboratory in India, he continued to explore challenging problems such as the study of cross-correlations in relaxation. He has major contributions in the field of NMR quantum information processing and NMR quantum computing and has pioneered several experimental aspects. Additionally, Prof. Anil Kumar dedicated himself to popularising the power of the modern NMR methodology and has been largely responsible for the current wide-spread use of the technique in India.
Prof. Anil Kumar was widely respected as a mentor and had a large number of PhD students. Whilst demanding the highest possible academic standards from his students, Anil also granted total freedom to all his co-workers. This open attitude of Anil helped all his students to achieve academic excellence of high standards. Anil’s passion and dedication to science in general and NMR in particular was of exemplary standards. His cheerful laughter in the IISc Department of Physics corridors will be sorely missed. In his passing away, the NMR world has lost a scientist of very high caliber.