The structural elements of phospholipase A2 affecting the enhancement of 8-anilinonaphthalene-1-sulfonate fluorescence.
The binding of the apolar fluorescent dye 8-anilinonaphthalene-1-sulfonate (ANS) to Naja naja atra and Bungarus multicinctus phospholipase A2 (PLA2) as well as the ANS fluorescence enhancement of PLA2-ANS complexes were pH-dependent. However, the pH-dependent curves and the ionizable groups perturbed by the binding of ANS were essentially different for the two PLA2 enzymes. Methylation of His residue or removal of the N-terminal octapeptide made the ANS fluorescence of PLA2-ANS complexes become less sensitive to pH changes. Moreover, the N-terminus-removed derivatives showed the same fluorescence-pH profiles. These results, together with the findings that the His residue and the N-terminal residues might locate around the ANS-binding site, suggested that the His residue and N-terminus of the two PLA2 enzymes may interact electrostatically with the bound ANS, and that ionization of these residues should appreciably affect the ANS fluorescence.
Chang
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Department of Biochemistry, Kaohsiung Medical College, Taiwan, ROC.
Wen
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Chang
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D000817:Anilino Naphthalenesulfonates / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004546:Elapid Venoms / Q000201:enzymology*; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D010179:Pancreas / Q000201:enzymology; D010741:Phospholipases A / Q000737:chemistry*; D054467:Phospholipases A2; D017510:Protein Folding; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence
D000817:Anilino Naphthalenesulfonates; D004546:Elapid Venoms; D005456:Fluorescent Dyes; C027132:1-anilino-8-naphthalenesulfonate; D010741:Phospholipases A; D054467:Phospholipases A2