The mammalian neprilysin (NEP) family comprises at least seven members: NEP itself, Kell blood group antigen (KELL), the endothelin-converting enzymes (ECE-1 and ECE-2), the enzyme PEX, associated with X-linked hypophosphataemia, "X-converting enzyme" (XCE) a CNS-expressed orphan peptidase and a soluble, secreted endopeptidase (SEP). These zinc metallopeptidases are all type II integral membrane proteins. Where identified, these enzymes have roles in the processing or metabolism of regulatory peptides and therefore represent potential therapeutic targets. A distinct feature of ECE-1 species is their existence as distinct isoforms differing in their N-terminal cytoplasmic tails. These tails play a role in enzyme targeting and turnover with di-leucine and tyrosine-based motifs affecting localization. Additional anchorage of these enzymes can also occur through palmitoylation. Bacterial homologues of the neprilysin family exist, for example the products of the pepO genes from L. lactis and S. parasanguis, and a recently described gene product of P. gingivalis which is an ECE-1 homologue that can catalyse the conversion of big endothelin to endothelin. A genomics based approach to understanding the functions of this proteinase family is aided by the completion of the C. elegans and Drosophila genomes, both of which encode multiple copies of NEP-like enzymes.

Abstract-The potent vasoconstrictor endothelin-1 (ET-1) is secreted constitutively by endothelial cells and has been implicated in the pathophysiology of several cardiovascular diseases. It is generated from its inactive intermediate, big

Endothelin-converting enzyme-1 (ECE-1) is a critical enzyme in the biosynthesis of the potent vasoconstrictor peptide endothelin and exists in several isoforms. Anti-peptide antibodies raised against epitopes in the distinct N-terminal cytoplasmic tails of the rat ECE-1 isoforms have been obtained. By using these antibodies in Western blot analysis and immunofluorescence studies, we have shown that cultures of transformed rat lung vascular endothelial cells treated with the metalloprotease inhibitor phosphoramidon and untreated cells express ECE-1K K only, whereas human umbilical vein endothelial cells express ECE-1K K and ECE-1L L. The ECE-1 isoforms expressed in CHO-K1 cells transfected with rat cDNA to ECE-1K K and ECE-1L L could be immunoprecipitated by using the appropriate isospecific antibody.z 1998 Federation of European Biochemical Societies.

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In this work, a statistical metric called the Mahalanobis distance (MD) is used to compare gas chromatography separation conditions. In the two-sample case, the MD computes the distance between the means of the multivariate probability distributions of two groups. Two gas chromatography columns of the same polarity but differing length and film thickness were utilized for the analysis of fatty acid methyl esters in biodiesel fuels. Biodiesel feedstock samples representing classes of canola, coconut, flaxseed, palm kernal, safflower, soy, soyabean, sunflower, tallow, and waste grease were used in our experiments. Data sets measured from each column were aligned with the correlated optimized warping (COW) algorithm prior to principal components analysis (PCA). The PC scores were then used to compute the MD. Differences between the data produced by each column were determined by converting the MD to its corresponding p-value using the F-distribution. The combination of COW parameters that maximized the p-value were determined for each feedstock separately. The results demonstrate that chromatograms from each column could be optimally aligned to minimize the MD derived from the PC-transformed data. The corresponding p-values for each feedstock type indicated that the two column conditions could produce data that were not statistically different. As a result, the slight loss of resolution using a faster column may be acceptable based on the application for which the data are used.