Abstract
The Mo-S based inorganic salt ATM (ammonium tetrathiomolybdate) and cysteine containing peptides can form self-assembled adlayers on Au surfaces and these modified electrode materials exhibit miscellaneous catalytic activities. The ATM modified Au electrode catalyses the evolution of H-2 from water even in the presence of O-2 and other inhibitors. Moreover, water insoluble iron-porphyrins get immobilised on this construct through physiadsorption and thus it becomes a favourable ORR (O-2 reduction reaction) catalyst. A naturally occurring peptide Ay(1-19), containing native cysteine residues, spontaneously forms an ordered SAM (self-assembled monolayer) on Au and upon heme binding this construct can catalyse the ORR with a higher catalytic rate compared to synthetic metallo-porphyrin based ORR catalysts. Human A beta(1-16), appended with a cysteine residue at its C-terminus, gets readily immobilised on Au surfaces by SAM formation. These A beta(Cys) constructs represent different isoforms of A beta in the absence and in the presence of various coadsorbant thiols. Upon individual as well as simultaneous binding of heme and Cu, these structurally different A beta(Cys) constructs exhibit diverse trends in generating oxidative stress, in vitro.