The Investigation of the Interaction between Lomefloxacin and Human Serume Albumin by Specteroscopic Methods

• Main Authors: F. S. Goldouzian, Z. S. Goldouzian, M. Momen Heravi, J. Khanchamani
• Format: Article
• Language: English
• Published: Islamic Azad University 2012-03-01
• Series: Journal of Chemical Health Risks
• Subjects: Human serum albumin; Lomefloxacin; Fluorescence spectroscopy; Fluorophore; Fluoroquinolone
• Online Access: http://www.jchr.org/index.php/JCHR/article/view/35

<div style="mso-element: para-border-div; border: none; border-top: solid windowtext 1.0pt; mso-border-top-alt: solid windowtext .5pt; padding: 1.0pt 0cm 0cm 0cm;"><p class="MsoNormal" style="margin-bottom: .0001pt; text-align: justify; line-height: 150%; mso-layout-grid-align: none; text-autospace: none; border: none; mso-border-top-alt: solid windowtext .5pt; padding: 0cm; mso-padding-alt: 1.0pt 0cm 0cm 0cm;"><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif';" lang="EN-CA">Mechanism of the binding of lomefloxacin (LMF) with human serum albumin has been studied at physiological pH (7.4) using fluorescence spectroscopic technique. LMF is a third-generation fluoroquinolone antibiotic that exhibits striking potency against a broad spectrum of Gram-negative and Gram-positive bacteria through inhibition of DNA gyrase. Lomefloxacin </span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif'; mso-ansi-language: EN-US; mso-bidi-language: FA;">is a drug that is excreted in urine and has very variable systemic absorption</span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif';" lang="EN-CA">. Human serum albumin (HSA) is the most important and abundant constituent of blood plasma and serves as a protein storage component. Recently, the three-dimensional structure of HSA was determined through X-ray crystallographic measurement. Fluorescence studies showed that (LMF) has an ability to quench the intrinsic fluorescence of HSA through a static quenching  procedure  according to the Stern–Volmer equation .LMF showed two types of binding sites, the first having a very high affinity (1/72 </span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif';" lang="AR-SA">×</span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif';" lang="EN-CA">10⁷M^-1) and a secondary binding site with an affinity two orders lower than the primary site. The number of binding sites for complex: HSA-LMF at 280 nm was calculated </span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif'; mso-ansi-language: EN-US;">1</span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif'; mso-ansi-language: EN-US; mso-bidi-language: FA;">and</span><span style="font-size: 9.5pt; line-height: 150%; font-family: 'Times New Roman','serif';" lang="EN-CA">0.5. The microenvironment of tryptophan and tyrosin residues and more hydrophobic of fluorophores microenvironment were changed and disturbed by the blue shift in maximum wavelength and decreased in fluorescence intensity in the presence of lomefloxacin revealed  decreased polarity of the fluorophores. The binding site for LMF is in a hydrophobic pocket in the sub-domain II A of HSA.</span></p></div>