title: Reaction of N-(3-pyrene)maleimide with thiol groups of reticulocyte ribosomes.
abstract: The reaction of N-(3-pyrene)maleimide with thiol groups of rabbit reticulocyte ribosomes offers a possible fluorescent probe for studying ribosomal structure and conformation. At relatively low concentrations of N-(3-pyrene)maleimide a group of 30-40 readily reactive sulfhydryl residues is derivatized. The major ribosomal proteins containing these thiol groups are identified as S2 + S3, S5, S7, S8, S29, S31, S32, L1, L5, L6, L10 + L14, L15, L18 + L19, and L36. Ribosomal activity, as measured by the nonenzymic binding of phenylalanyl-tRNA and polyphenylalanine synthesis, is inhibited by this degree of reaction with N-(3-pyrene)maleimide. The inhibition is relieved by the prior binding of polyuridylic acid to the ribosomes while the extent of derivatization by N-(3-pyrene)-maleimide is diminished only slightly. The average relative polarization of the fluorescence of the ribosomal bound N-(3-pyrene)maleimide changes significantly with the degree of derivatization of ribosomal thiol groups or with the binding of polyuridylic acid, indicating the value of such a fluorescent thiol-derivatizing agent as a probe of ribosomal structure.
mesh_terms: D000818:Animals; D005033:Ethylmaleimide / Q000378:metabolism; D007700:Kinetics; D008301:Maleimides / Q000378:metabolism*; D011485:Protein Binding; D011721:Pyrenes / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013439:Sulfhydryl Reagents
chemical_list: D008301:Maleimides; D011721:Pyrenes; D012269:Ribosomal Proteins; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; C003944:N-(3-pyrene)maleimide; D005033:Ethylmaleimide