Design and synthesis of MMP inhibitors with appended fluorescent tags for imaging and visualization of matrix metalloproteinase enzymes

We describe the synthesis, MMP-2 and 9 potency, and in vitro evaluation of a series of α-sulfone hydroxmate MMP inhibitors conjugated to a series of dyes with different absorption/emission lamina maxima’s that can be used to visualize tumors.     

The role of electrostatic interactions in the mechanism of peptide bond hydrolysis by a Ser-Lys catalytic dyad.

General-base catalysis in the active site of serine proteases is carried out by the imidazole side chain of a histidine. During formation of the transition state, an adjacent carboxylic acid group stabilizes the positive charge that forms on the general-base catalyst and as a result contributes several orders of magnitude to the catalytic efficiency of these enzymes. In the recently discovered family of self-cleaving proteins exemplified by the LexA repressor of Escherichia coli, instead of the imidazole of a histidine, the active-site general-base catalyst was found to be the epsilon-amino of a lysine. The considerably higher capacity of the lysine side chain for proton acceptance raises interesting questions concerning the role of electrostatic interactions in the mechanism of proton transfer by this highly basic group. The negative charge elimination studies described here and their effects on the kmax and pK of LexA self-cleavage are consistent with a model in which electrostatic interactions between an acidic side chain and the general-base catalyst form a barrier to proton transfer. The implications are that the epsilon-amino group, unlike the imidazole group, is capable of effecting proton transfer without the intervention of a countercharge.     

Serum beta 2 microglobulin in adult myeloid acute leukemias

Serum beta 2 microglobulin levels, measured by radioimmunoassay (Phadebas test), were found increased in acute myeloid leukemias at diagnosis. Serum beta 2 microglobulin levels were significantly higher in patients with monocytic leukemias (13 patients, M4-M5 FAB classification) than in those with other cytological types (18 patients). Beta 2 microglobulin levels at diagnosis were correlated with serum lysozyme levels, but they were not correlated with blood blast counts, serum LDH and ferritin levels. 195 serum beta 2 microglobulin measurements were made serially in 30 patients with acute myeloid leukemias in first remission. Compared to values at diagnosis, beta 2 microglobulin levels in remission were significantly decreased. Out of 30 patients in remission 12 had increased serum beta 2 microglobulin levels (greater than 3 mg/l). Serial measurements were not predictive for relapses.     

Macamides and their synthetic analogs: Evaluation of in vitro FAAH inhibition

Maca (Lepidium meyenii), a traditional food crop of the Peruvian Andes is now widely touted as a dietary supplement. Among the various chemical constituents isolated from the plant are a unique series of non-polar, long-chain fatty acid N-benzylamides known as macamides. We have synthesized 11 of the 19 reported macamides and have tested each as potential inhibitors of the human enzyme, fatty acid amide hydrolase (FAAH). The five most potent macamides were FAAH inhibitors (IC₅₀ = 10–17 μM). These amides were derivatives of oleic, linoleic and linolenic acids and benzylamine or 3-methoxybenzylamine. Of the three compounds evaluated in a pre-incubation time study, two macamides were not irreversible inhibitors of FAAH. The third, a carbamate structurally related to macamides, was shown to be an irreversible inhibitor of FAAH (IC₅₀ = 0.153 μM).