I was primarily involved in the synthesis of azobenzene based peptide bioconjugates for designing artificial nucleases. Metal binding peptides were attached to azobenzene based chromophores and indispensable characteristics like facile photo isomerisability and structural difference between the trans and cis isomers were explored. Metal-peptide-Azobenzene conjugates showed DNA cleavage activity and investigation on photo- control of DNA cleavage activities by these conjugates are in progress. I was also involved in the development of water-soluble photocleavable protective groups and its application for design of tumor-targeting paclitaxel prodrugs. Chemical modification of proteins (myoglobin mutants) with photo-active organic groups (nitrobenzyl derivatives, azobenzene derivatives), to photo-control the structure and functions of proteins. Proteins modified with photo-active molecules were characterized by LC-MS techniques and other spectroscopic techniques.

(II) Research work done at the Department of Chemical Sciences, TATA INSTITUTE OF FUNDAMENTAL RESARCH (TIFR), MUMBAI, INDIA.

My research was focused on the Electrospray ionization mass spectrometry (ESI-MS) of proteins. We observed that the maximum positive charge state of the gaseous protein ions is directly related to the number of free surface exposed basic groups (lysine, arginine and histidine) whereas the maximum negative charge state is related to the number of free surface exposed acidic groups (aspartic acid and glutamic acid) of the protein. The free surface exposed basic groups or acidic groups are those which are not involved in any interaction with surrounding amino acids residues and have high propensity to carry formal positive or negative charge. Information on the free surfaced exposed basic groups or acidic groups of proteins were obtained from the x-ray crystal structures. Thus, we have shown a direct correlation of the crystal structure of proteins with the maximum positive and negative charge-states of gaseous protein ions produced by electrospray ionization.

I was also involved in the studies on ESI-MS of Cytochrome P450cam to probe the tertiary structural changes on heme dissociation, and Chemical modification of lysine residues of cytochrome c by acylation reaction to identify the nucleophilic character of various lysine residues in cytochrome c. Specific acylation of the lysine residues of cytochrome c was identified by Collision Induced Dissociation mass spectrometry of the tryptic digest of cytochrome c.

(III) Doctoral Research work at School of Chemistry, Department of Inorganic Chemistry, and National Centre for Ultra fast Processes, UNIVERSITY OF MADRAS, CHENNAI, INDIA.

My doctoral thesis focus on the synthesis and photochemistry of nickel(II) azamacrocyclic complexes. Nitrogen rich azamacrocyclic ligand (nitrogen rich cyclic molecules) and its nickel complexes were synthesized. Photooxidation of nickel(II) azamacrocyclic complexes, resulted in the formation of stable trivalent nickel macrocycles. Time resolved nanosecond laser flash photolysis of the nickel(II) azamacrocylces revealed the transient hydrated electron absorption features, on UV excitation of the of nickel(II) azamacrocyclic complexes. The investigation enlightened that nickel(II) azamacrocyclic complexes posses Charge-transfer to solvent absorption character in the UV region.