Dansylated adenine as a molecular probe for exploring hydrophobic pocket of bovine serum albumin (BSA) and its utility for mercury ion recognition

Abstract

Bovine serum albumin (BSA) is a well characterized protein with a distinct hydrophobic region in its molecular architecture. Literature survey indicates that the tertiary structure of BSA comprises of homologous domains with subdomains (I, II and III). It has been postulated that hydrophobic pocket of subdomain II is dynamic in nature and it carves out two sites I and II that encompass amino acids tryptophan, tyrosine and phenyl alanine in specific positions. BSA usually binds to different ionic and molecular species at site I (with a cavity size of 2.53Å) or site II (cavity size 2.6) depending upon appropriate combination of hydrophobic, hydrogen bonding and electrostatic interactions [7]. In order to study the dynamic nature of hydrophobic pocket of BSA and its role in ionic and molecular recognition, we have synthesized a new dansylated adenine (DA) that exhibits solvatochromism and fluorescence enhancement on interaction with BSA in aqueous media. Detailed fluorescence and absorption spectral studies reveal that it is possible to lock one of the sites (site I) by synthesized dansylated adenine while the remaining site can be used for selective interaction with small organic molecules or metal ions. The specificity of this interaction at site II to mercury has been examined to understand possible locking of active sites of proteins for metal ion recognition to pave way for innovative molecular technologies.