Abstract-In the arena of software, data mining technology has been considered as useful means for identifying patterns and trends of large volume of data. This approach is basically used to extract the unknown pattern from the large set of data for business as well as real time applications. It is a computational intelligence discipline which has emerged as a valuable tool for data analysis, new knowledge discovery and autonomous decision making. The raw, unlabeled data from the large volume of dataset can be classified initially in an unsupervised fashion by using cluster analysis i.e. clustering the assignment of a set of observations into clusters so that observations in the same cluster may be in some sense be treated as similar. The outcome of the clustering process and efficiency of its domain application are generally determined through algorithms. There are various algorithms which are used to solve this problem. In this research work two important clustering algorithms namely centroid based K-Means and representative object based FCM (Fuzzy C-Means) clustering algorithms are compared. These algorithms are applied and performance is evaluated on the basis of the efficiency of clustering output. The numbers of data points as well as the number of clusters are the factors upon which the behaviour patterns of both the algorithms are analyzed. FCM produces close results to K-Means clustering but it still requires more computation time than K-Means clustering.

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Edited by Charles SamuelViperin is an endoplasmic reticulum-associated antiviral responsive protein that is highly up-regulated in eukaryotic cells upon viral infection through both interferon-dependent and independent pathways. Viperin is predicted to be a radical S-adenosyl-L-methionine (SAM) enzyme, but it is unknown whether viperin actually exploits radical SAM chemistry to exert its antiviral activity. We have investigated the interaction of viperin with its most firmly established cellular target, farnesyl pyrophosphate synthase (FPPS). Numerous enveloped viruses utilize cholesterol-rich lipid rafts to bud from the host cell membrane, and it is thought that by inhibiting FPPS activity (and therefore cholesterol synthesis), viperin retards viral budding from infected cells. We demonstrate that, consistent with this hypothesis, overexpression of viperin in human embryonic kidney cells reduces the intracellular rate of accumulation of FPPS but does not inhibit or inactivate FPPS. The endoplasmic reticulum-localizing, N-terminal amphipathic helix of viperin is specifically required for viperin to reduce cellular FPPS levels. However, although viperin reductively cleaves SAM to form 5-deoxyadenosine in a slow, uncoupled reaction characteristic of radical SAM enzymes, this cleavage reaction is independent of FPPS. Furthermore, mutation of key cysteinyl residues ligating the catalytic [Fe 4 S 4 ] cluster in the radical SAM domain, surprisingly, does not abolish the inhibitory activity of viperin against FPPS; indeed, some mutations potentiate viperin activity. These observations imply that viperin does not act as a radical SAM enzyme in regulating FPPS. Radical S-adenosyl-L-methionine-dependent (SAM)3 enzymes constitute a superfamily of enzymes that use SAM to generate free radicals (1-4). The superfamily is typified by a common CXXXCXXC motif, the cysteinyl residues of which coordinate a [Fe 4 S 4 ] cluster that is essential for radical generation. These enzymes catalyze a remarkably wide range of reactions involving an equally diverse set of substrates (2). For example, radical SAM-dependent enzymes participate in the biosynthesis of herbicides, antibiotics, vitamins, co-factors such as biotin and thiamin, and various other natural products (2, 5-8). They also function in the modification of ribosomal and transfer RNAs (9, 10) and DNA repair (11) and in the post-translational modification of peptides and proteins (12)(13)(14). Sequence analyses indicate that there are potentially thousands of members of the radical SAM superfamily, but to date, relatively few of these enzymes have been isolated and characterized (15, 16). Radical SAM enzymes were until recently thought to be confined to the microbial realm but intriguingly have now been identified in higher aerobic organisms, including plants and animals (3).Central to the mechanism of all radical SAM enzymes is the generation of a highly reactive 5Ј-deoxyadenosyl radical (Ado ⅐ ) (1,4,17). This is accomplished through one-electron reduction of SAM by the [Fe 4...

Viperin plays an important and multifaceted role in the innate immune response to viral infection.  Viperin is also notable as one of very few radical SAM-dependent enzymes present in higher animals; however, the enzyme appears broadly conserved across all kingdoms of life, which suggests that it represents an ancient defense mechanism against viral infections.  Although viperin was discovered some 20 years ago, only recently was the enzyme’s structure determined and its catalytic activity elucidated.  The enzyme converts CTP to 3’,4’-didehydro-3’-deoxy-CTP, which functions as novel chain-terminating antiviral nucleotide when misincorporated by viral RNA-dependent RNA polymerases.  Moreover, in higher animals, viperin interacts with numerous other host and viral proteins, and it is apparent that this complex network of interactions constitutes another important aspect of the protein’s antiviral activity.  An emerging theme is that viperin appears to facilitate ubiquitin-dependent proteasomal degradation of some of the proteins it interacts with.  Viperin- targeted protein degradation contributes to the antiviral response either by down-regulating various metabolic pathways important for viral replication or by directly targeting viral proteins for degradation. Here, we review recent advances in our understanding of the structure and catalytic activity of viperin, together with studies investigating the interactions between viperin and its target proteins.  These studies have provided detailed insights into the biochemical processes underpinning this unusual enzyme’s wide-ranging antiviral activity. We also highlight recent intriguing reports that implicate a broader role for viperin in regulating non-pathological cellular processes, including thermogenesis and protein secretion.

The radical SAM enzyme, viperin, exerts a wide range of antiviral effects through both the synthesis of the antiviral nucleotide 3′-deoxy-3′,4′-didehydro-CTP (ddhCTP) and through its interactions with various cellular and viral proteins. Here we investigate the interaction of viperin with hepatitis C virus nonstructural protein 5A (NS5A) and the host sterol regulatory protein, vesicle-associated membrane protein A (VAP-33). NS5A and VAP-33 form part of the viral replication complex that is essential for replicating the RNA genome of the hepatitis C virus. Using transfected enzymes in HEK293T cells, we show that viperin binds independently to both NS5A and the C-terminal domain of VAP-33 (VAP-33C) and that this interaction is dependent on the proteins being colocalized to the ER membrane. Coexpression of VAP-33C and NS5A resulted in changes to the catalytic activity of viperin that depended upon viperin being colocalized to the ER membrane. The viperin-NS5A-VAP-33C complex exhibited the lowest specific activity, indicating that NS5A may inhibit viperin’s ability to synthesize ddhCTP. Coexpression of viperin with NS5A was also found to significantly reduce cellular NS5A levels, most likely by increasing the rate of proteasomal degradation. An inactive mutant of viperin, unable to bind the iron–sulfur cluster, was similarly effective at reducing cellular NS5A levels.