Probing the interaction of cephalosporin antibiotic-ceftazidime with human serum albumin: A biophysical investigation.

The fate of drug administered to a living organism depends on drug's pharmacokinetics as well as pharmacological behavior. Serum albumins (proteins in blood plasma of human) act as a carrier molecule to deliver the drug at specific site. In the present study, we have explored the mechanism of interaction between cephalosporin antibiotic-ceftazidime (CFD) and human serum albumin (HSA) by spectroscopic and molecular docking studies. Quenching of HSA fluorescence by CFD inferred that it binds to HSA through static quenching mechanism; with binding affinity in order of 104M-1. Fluorescence resonance energy transfer (FRET) results shows that donor and acceptor molecule are at 2.08nm apart and also reflects the high probability of energy transfer between HSA and CFD. Change in secondary structure as well as microenvironment around both tryptophan and tyrosine residue, were monitored by Circular Dichroism (CD) and Synchronous fluorescence spectroscopy respectively; confirms that CFD increases the alpha helical secondary structure as well as altered the environment around tryptophan and tyrosine. The specific binding site of CFD on HSA was determined by site-specific markers and molecular docking methods. CFD preferably bind to subdomain IIIA (Sudlow site II) on HSA.