Antenna effect and phosphorescence spectra to find the location of drug tetracycline in bovine β-lactoglobulin A
- 63 Downloads
A ternary system comprising of a Eu(III) complex of the drug Tetracycline hydrochloride (Eu3TC) bound to bovine β-lactoglobulin variant A (BLGA) in aqueous buffer at physiological pH (pH = 7.4) has been investigated to exploit the enhanced “antenna effect” to locate the bound drug and find the microenvironment of the binding site. Steady-state and time-resolved emission studies at room temperature as well as at 77 K have been carried out to evaluate the binding parameters in the binary system consisting of BLGA and tetracycline hydrochloride (TC). Low-temperature phosphorescence studies at 77 K of pure BLGA confirm Trp 19 to be the emitting residue, while Trp 61 is silent. Enhancement of BLGA phosphorescence emission in the ternary system at 77 K indicates that Trp 19 is very close to Eu(III) in the Eu3TC complex. The molecular docking results further confirm that TC binds close to Trp 19 in a hydrophobic domain. The results thus obtained can provide guidelines to design and synthesize target-oriented drugs as well as suitable bio-probes.
KeywordsAntenna effect Bovine β-lactoglobulin Tetracycline Fluorescence Phosphorescence Accessible surface area
S. G. gratefully acknowledges the Department of Science and Technology (DST), Government of India (Grant no.: SB/S1/PC-003/2013), and MBR gratefully acknowledges UGC [Minor Research Project No.F.PS-146/15-16 (ERO)] for financially supporting this work.
- 5.Chobert JM, Haertlé T (1997) Protein-lipid and protein–flavor interactions. In: Damodaran S, Paraf A (eds) Food proteins and their applications. Marcel-Dekker, New York, pp 143–170Google Scholar
- 6.Hambling SM, McAlpine AS, Sawyer L (1992) β-Lactoglobulin. In: Fox PF (ed) Advanced dairy chemistry 1: proteins. Elsevier, London, pp 141–190Google Scholar
- 10.Rudek M, Figg W, Dyer V, Dahut W, Turner M, Steinburg S (2000) A phase I clinical trial of oral Col-3, a matrix metalloproteinase inhibitor, administered daily in patients with refractory metastatic cancer [abstract]. Proc Am Assoc Cancer Res 41:612Google Scholar
- 22.Bevington PR (1969) Data reduction and error analysis for the physical sciences. McGraw Hill, New York, pp 235–237Google Scholar
- 23.FELIX 32, version 1.1 (2003) Operation manual. Photon Technology International, EdisonGoogle Scholar
- 27.Hubbard SJ, Thorton JM (1993) NACESS computer program. Department of Biochemistry and Molecular Biology, University College, LondonGoogle Scholar
- 31.Mukherjee M, Saha Sardar P, Ghorai SK, Samanta SK, Roy AS, Dasgupta S, Ghosh S (2012) Interaction of multitryptophan protein with drug: an insight into the binding mechanism and the binding domain by time resolved emission, anisotropy, phosphorescence and docking. J Photochem Photobiol B 115:93–104CrossRefPubMedGoogle Scholar
- 40.Pal A, Maity SS, Samanta S, Saha Sardar P, Ghosh S (2010) Interaction of the excited state intramolecular proton transfer probe 3- hydroxy—2- naphthoic acid with poly N- Vinyl -2- pyrrolidone polymer in water: an insight into the water structure in the binding region. J Luminescence 130:1975–1982CrossRefGoogle Scholar
- 43.Mukherjee M, Ghosh R, Chattopadhyay K, Ghosh S (2016) Stepwise unfolding of a multi-tryptophan protein MPT63 with immunoglobulin-like fold: detection of zone-wise perturbation during guanidine hydrochloride-induced unfolding using phosphorescence spectroscopy. RSC Adv 66:61077–61087CrossRefGoogle Scholar
- 44.Cho Y, Batt CA, Sawyer L (2016) Probing the retinol-binding site of bovine betalactoglobulin. J Biol Chem 269:11102–11107Google Scholar