alpha-Synuclein is a component of the abnormal protein depositions in senile plaques and Lewy bodies of Alzheimer's disease (AD) and Parkinson's disease respectively. The protein was suggested to provide a possible nucleation centre for plaque formation in AD via selective interaction with amyloid beta/A4 protein (Abeta). We have shown previously that alpha-synuclein has experienced self-oligomerization when Abeta25-35 was present in an orientation-specific manner in the sequence. Here we examine this biochemically specific self-oligomerization with the use of various metals. Strikingly, copper(II) was the most effective metal ion affecting alpha-synuclein to form self-oligomers in the presence of coupling reagents such as dicyclohexylcarbodi-imide or N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline. The size distribution of the oligomers indicated that monomeric alpha-synuclein was oligomerized sequentially. The copper-induced oligomerization was shown to be suppressed as the acidic C-terminus of alpha-synuclein was truncated by treatment with endoproteinase Asp-N. In contrast, the Abeta25-35-induced oligomerizations of the intact and truncated forms of alpha-synuclein were not affected. This clearly indicated that the copper-induced oligomerization was dependent on the acidic C-terminal region and that its underlying biochemical mechanism was distinct from that of the Abeta25-35-induced oligomerization. Although the physiological or pathological relevance of the oligomerization remains currently elusive, the common outcome of alpha-synuclein on treatment with copper or Abeta25-35 might be useful in understanding neurodegenerative disorders in molecular terms. In addition, abnormal copper homoeostasis could be considered as one of the risk factors for the development of disorders such as AD or Parkinson's disease.

Aims: An investigation was carried out on an oxidative and SDS-stable alkaline protease secreted by Bacillus clausii of industrial significance. Methods and Results: Maximum enzyme activity was produced when the bacterium was grown in the medium containing (g l )1 ): soyabean meal, 15; wheat flour, 10; liquid maltose, 25; K 2 HPO 4 , 4; Na 2 HPO 4 , 1;MgSO 4 AE7H 2 O, 0AE1; Na 2 CO 3 , 6. The enzyme has an optimum pH of around 11 and optimum temperature of 60°C. The alkaline protease showed extreme stability towards SDS and oxidizing agents, which retained its activity above 75 and 110% on treatment for 72 h with 5% SDS and 10% H 2 O 2 , respectively. Inhibition profile exhibited by phenylmethylsulphonyl fluoride suggested that the protease from B. clausii belongs to the family of serine proteases. Conclusions: Bacillus clausii produced high levels of an extracellular protease having high stability towards SDS and H 2 O 2 . Significance and Impact of the Study: The alkaline protease from B. clausii I-52 is significant for an industrial perspective because of its ability to function in broad pH and temperature ranges in addition to its tolerance and stability in presence of an anionic surfactant, like SDS and oxidants like peroxides and perborates. The enzymatic properties of the protease also suggest its suitable application as additive in detergent formulations.

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