Stromelysin-1 is a member of a tissue metalloproteinase family whose members are all capable of degrading extracellular matrix components. A truncated form of human fibroblast prostromelysin 1 lacking the C-terminal, hemopexin-like domain has been expressed in Escherichia coli and purified to homogeneity. Treatment of this short form of prostromelysin with (aminophenyl)mercuric acetate resulted in activation and loss of the propeptide in a manner identical with the wild-type, full-length protein. Kinetic comparisons using Nle11-substance P as a substrate showed that the wild-type stromelysin and the truncated form of the enzyme had similar kcat and Km values. Likewise, both enzymes displayed similar Ki values for a hydroxamate-containing peptide inhibitor. Taken together, these results indicate that the C-terminal portion of stromelysin is not required for proper folding of the catalytic domain, maintenance of the enzyme in a latent form, activation with an organomercurial, cleavage of a peptide substrate, or interaction with an inhibitor. Moreover, the active short form of stromelysin displayed a reduction in the C-terminal heterogeneity, a characteristic degradation of the full-length stromelysin, and thereby provides a more suitable protein for future structural studies.

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Combinatorial chemistry is gaining wide appeal as a technique for generating molecular diversity. Among the many combinatorial protocols, the split/recombine method is quite popular and particularly efficient at generating large libraries of compounds. In this process, polymer beads are equally divided into a series of pools and each pool is treated with a unique fragment; then the beads are recombined, mixed to uniformity, and redivided equally into a new series of pools for the subsequent couplings. The deviation from the ideal equimolar distribution of the final products is assessed by a special overall relative error, which is shown to be related to the Pearson statistic. Although the split/recombine sampling scheme is quite different from those used in analysis of categorical data, the Pearson statistic is shown to still follow a chi2 distribution. This result allows us to derive the required number of beads such that, with 99% confidence, the overall relative error is controlled to be less than a pregiven tolerable limit L1. In this paper, we also discuss another criterion, which determines the required number of beads so that, with 99% confidence, all individual relative errors are controlled to be less than a pregiven tolerable limit L2 (0 < L2 < 1).

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