@mbu.asia
Associate Professor
Mohan Babu University, Tirupati
Ph.D. in Chemistry
General Chemistry, Environmental Chemistry, Organic Chemistry
Scopus Publications
R. Jagan, D. Sathya, and K. Sivakumar
Pleiades Publishing Ltd
Pandian Ramesh, Selvarajan Sigamani Sundaresan, Nagaraj Shobana, Thangaraj Vinuchakkaravarthy, Kandasamy Sivakumar, Sayed Yasien, and Mondikalipudur Nanjappa Gounder Ponnuswamy
International Union of Crystallography (IUCr)
Crystal structures of hemoglobin (Hb) from two flightless birds, ostrich (Struthio camelus) and turkey (Meleagris gallopova), were determined. The ostrich Hb structure was solved to a resolution of 2.22 Å, whereas two forms of turkey Hb were solved to resolutions of 1.66 Å (turkey monoclinic structure; TMS) and 1.39 Å (turkey orthorhombic structure; TOS). Comparison of the amino-acid sequences of ostrich and turkey Hb with those from other avian species revealed no difference in the number of charged residues, but variations were observed in the numbers of hydrophobic and polar residues. Amino-acid-composition-based computation of various physical parameters, in particular their lower inverse transition temperatures and higher average hydrophobicities, indicated that the structures of ostrich and turkey Hb are likely to be highly ordered when compared with other avian Hbs. From the crystal structure analysis, the liganded state of ostrich Hb was confirmed by the presence of an oxygen molecule between the Fe atom and the proximal histidine residue in all four heme regions. In turkey Hb (both TMS and TOS), a water molecule was bound instead of an oxygen molecule in all four heme regions, thus confirming that they assumed the aqua-met form. Analysis of tertiary- and quaternary-structural features led to the conclusion that ostrich oxy Hb and turkey aqua-met Hb adopt the R-/RH-state conformation.
S. Kumar, , K. K. Sivakumar, Mohammed Kaso Sado, Gutu Ofgaa Ternesgen Garoma, , , and
Sumy State University
Srinivasan Kumar, , K. K. Sivakumar, Naol Dessalegn Dejene, Temesgen Garoma, Asagid Tadesse, , , , and
Sumy State University
R. Jagan and K. Sivakumar
Pleiades Publishing Ltd
M. Muralidharan, R. Thiyagarajan, K. Sivakumar, and K. Sivaji
Springer Science and Business Media LLC
K. Saminathan, S. Athimoolam, N. Karthikeyan, and K. Sivakumar
Elsevier BV
M. Dhilip, V. Anbarasu, K. Saravana Kumar, and K. Sivakumar
Author(s)
A series of Europium orthoferrites, Eu2-xFexO3 (x = 0 – 0.5) are successfully prepared by employing solid state reaction technique. The structural analysis through powder X-Ray diffraction technique reveals the multiphase formation of all the prepared compounds. Further, the unit cell visualization of all the prepared compounds confirms the change of crystal structure from cubic to orthorhombic phase. The crystal structure analysis confirms the typical framework of Eu – Fe – O chains with unprecedented ratio of Eu3+ and Fe3+ ions. The optical properties of prepared compounds are investigated using photoluminescence (PL) analysis. Upon excitation at 495 nm wavelength, the emission spectrum of prepared compounds exhibits a broad band in the range of 500-700nm with maximum intensity peak at 548 nm (Blue – 2.26eV). Hence, the substitution of Fe3+ ion yields with intrinsic blue photoluminescence (5D0 → 7F0) of Eu3+ and is easily shielded by the substitution of Fe3+ which may be due to the closer conduction band gap of Eu3+ (2.26 eV) with Fe3+ (2.67 eV). The schematic energy level diagram for Fe3+ in the Eu3+ host matrix has been proposed for the better understanding of photoluminescence processes. The variation of intensity of PL peak between 500 and 700 nm for the substitution of Fe in the range of x = 0 – 0.5 yields with interesting optical properties for exploring new phosphor materials for optoelectronic device fabrications.A series of Europium orthoferrites, Eu2-xFexO3 (x = 0 – 0.5) are successfully prepared by employing solid state reaction technique. The structural analysis through powder X-Ray diffraction technique reveals the multiphase formation of all the prepared compounds. Further, the unit cell visualization of all the prepared compounds confirms the change of crystal structure from cubic to orthorhombic phase. The crystal structure analysis confirms the typical framework of Eu – Fe – O chains with unprecedented ratio of Eu3+ and Fe3+ ions. The optical properties of prepared compounds are investigated using photoluminescence (PL) analysis. Upon excitation at 495 nm wavelength, the emission spectrum of prepared compounds exhibits a broad band in the range of 500-700nm with maximum intensity peak at 548 nm (Blue – 2.26eV). Hence, the substitution of Fe3+ ion yields with intrinsic blue photoluminescence (5D0 → 7F0) of Eu3+ and is easily shielded by the substitution of Fe3+ which may be due to the closer conduction ban...
N. Karthikeyan, G. Jaiganesh, V. Anbarasu, Partha Pratim Jana, and K. Sivakumar
Elsevier BV
K. Thiyagarajan and K. Sivakumar
Elsevier BV
Kamarajan Thiyagarajan, Munisamy Muralidharan, and Kandasamy Sivakumar
Springer Science and Business Media LLC
V. Anbarasu, M. Dhilip, K. Saravana Kumar, and K. Sivakumar
Springer Science and Business Media LLC
Kamarajan Thiyagarajan and Kandasamy Sivakumar
Springer Science and Business Media LLC
V. Anbarasu, M. Dhilip, K. Saravana Kumar, and K. Sivakumar
Springer Science and Business Media LLC
R. Padmavathy, N. Karthikeyan, D. Sathya, R. Jagan, R. Mohan Kumar, and K. Sivakumar
Elsevier BV
M. Muralidharan, V. Anbarasu, A. Elaya Perumal, and K. Sivakumar
Springer Science and Business Media LLC
N. Karthikeyan, Sivaprasad Ghanta, Samiran Misra, G. Jaiganesh, Partha Pratim Jana, and K. Sivakumar
Elsevier BV
K. Saminathan, R. Jagan, K. Sivakumar, and K. Saravanan
Springer International Publishing
M. Muralidharan, V. Anbarasu, A. Elaya Perumal, and K. Sivakumar
Springer Science and Business Media LLC
R. Padmavathy, N. Karthikeyan, D. Sathya, R. Jagan, R. Mohan Kumar, and K. Sivakumar
Royal Society of Chemistry (RSC)
A series of five dicarboxylic acid complexes of succinic acid and malic acid with various substituted amines have been synthesized and structurally analyzed; also the supramolecular organizations within their crystalline solids have been studied.
B. Sathyaseelan, E. Manikandan, K. Sivakumar, J. Kennedy, and M. Maaza
Elsevier BV