title: Synthesis of undecagold cluster molecules as biochemical labeling reagents. 2. Bromoacetyl and maleimido undecagold clusters.
abstract: Derivatives of heptakis[4,4',4"-phosphinidynetris(benzenemethanamine) ]undecagold, 1, molecular formula Au11(CN)3[P(C6H4CH2NH3)]7, are described. These include undecagold complexes with a single free primary amino group, a single bromoacetyl group, and a single maleimido group per molecule. Hydrolysis of mono(N-phthalyl)icosa(N-acetyl)-1 at pH 3.2 and 46 degrees C under anaerobic conditions and in the presence of NaBH3CN produces icosa(N-acetyl)-1. Partial acylation of 1 with 1.3 equiv of 2,3-dimethylmaleic anhydride followed by complete acetylation with acetic anhydride produces a mixture consisting largely of mono- and bis(dimethylmaleyl)peracetyl-1. Hydrolysis of 2,3-dimethylmaleimides at pH 3.2 for 1 at 25 degrees C produces a mixture of icosa(N-acetyl)-1, with a single free amino group, and nondea(N-acetyl)-1. This mixture can be quantitatively separated by cation-exchange chromatography at pH 7, giving homogeneous icosa(N-acetyl)-1 in an overall yield of 55%. Icosa(N-acetyl)-1 serves as the starting material for the synthesis of the alkylating derivatives mono(N-bromoacetyl)icosa(N-acetyl)-1 and mono[N-(p-maleimidobenzoyl)]icosa(N-acetyl)-1. These derivatives can be used for alkylating proteins in preparation for electron microscopy.
mesh_terms: D000085:Acetates / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D002852:Chromatography, Ion Exchange; D006046:Gold / Q000032:analysis; D008024:Ligands; D008301:Maleimides / Q000032:analysis; D050607:Organogold Compounds; D009942:Organometallic Compounds / Q000032:analysis
chemical_list: D000085:Acetates; D008024:Ligands; D008301:Maleimides; D050607:Organogold Compounds; D009942:Organometallic Compounds; C035797:undecagold; D006046:Gold