Metalloproteins are essential for a large number of basic processes of life including photosynthesis, respiration, detoxification against toxic substances, biosynthesis of hormones etc. The biochemical function of the metal ion in a metalloprotein depends on the oxidation state, as well as on the nature of the coordinating residues and the environment around the metal ion inside the protein cavity. Understanding of the properties of the metal ion in the protein and the molecular basis of the biochemical function of the metalloprotein present fascinating challenges to chemists and form the frontier of bioinorganic chemistry, a subject at the interface of inorganic chemistry and biological sciences.
Studies of novel metal complexes as models for the metal active site in proteins by several groups all over the world have led to significant understanding of the structure and electronic properties of metalloproteins. The complexity of the protein scaffold however can not be fully achieved by the synthetic analogues, thus study the metalloproteins themselves in vitro and use of protein engineering techniques to suitably modify the active site in order to specifically identify roles of individual residues on the properties of the metal centre in the protein have become important. Recent years have seen enormous activities in this rapidly ex-panding field all over the world both for unraveling the fundamental issues such as structure and biochemical function of metalloproteins as well as for their applications as biosensors and as industrial biocatalysts.
Some of the typical Metalloenzymes/metalloproteins that has attracted our interest consist of iron (heme) or copper ion(s) at their catalytic/active centers.
They carry out several vital metabolic functions.
Oxygen transport by hemoglobin in RBC involves a Heme center.
Conversion of O2 to H2O associated with active proton pump across the mitochrondrial membrane in the Cellular respiration by
- Identification of the factors responsible for stabilisation of the active structure and the nature of the dynamic fluctuations in the protein cavity.
- Understanding the mechanistic aspects of their functions.
- Develop novel enzymes capable of catalysing reactions of molecules which otherwise are not affected by the enzyme, eg., environmental pollutants such as pesticides etc. and design functional and stable metal active sites in proteins. We have been involved in the study of structural and mechanistic aspects of the biochemical function of electron transfer and redox metalloenzymes using various physicochemical techniques such as NMR (1 & 2D), Fluorescence (both equilibrium and time-resolved), Circular dichroism (CD), Stopped -flow kinetics, cyclic voltammetry, ESI-MS and Bioelectrochemistry of wild type, mutant proteins and their analogues with special interest on cytochrome c oxidase, cytochrome P450 and peroxidases. We are also involved in the study of interactions of surfactants and lipids with metal enzymes and their biochemical implications.