Shujaath Mehdi

Cell-penetrating inhibitors of calpain.

Inhibitors of the calcium-dependent cysteine protease calpain are described that are new analogs of the naturally-occurring compounds E-64 and leupeptin. These new derivatives, unlike the parent compounds, can inhibit calpain within cells. Their lack of charged groups probably accounts for this improved membrane permeability. These new inhibitors are proving useful in exploration of the role of calpain in many cellular processes, including platelet activation.

Inhibition of the proteolysis of rat erythrocyte membrane proteins by a synthetic inhibitor of calpain

A synthetic inhibitor of calpain protects rat erythrocyte membrane-associated cytoskeletal proteins from proteolytic degradation (IC50 = 1 microM) which occurs when the cells are rendered permeable to Ca++. Leupeptin, a naturally occurring inhibitor of the enzyme, does not afford any protection at concentrations up to 100 microM.

Improved posthypoxic recovery with a membrane-permeable calpain inhibitor

In vitro hippocampal slices from adult rats were subjected to transient hypoxia in the presence of a cell-penetrating, calpain inhibitor (Cbz-Val-Phe-H; MDL-28170). The posthypoxic recovery of synaptic potentials was greatly improved in protease inhibitor-treated slices relative to control slices. These findings support a role for calcium-activated proteolysis in the process of hypoxic pathophysiology.

A Stereoselective method to (E)- and (Z)-fluorovinyl phosphonates Utilizing Palladium(0) coupling methodology

Abstract The first stereoselective method to both (E)- and (Z)-fluorovinyl phosphonates from fluorovinyl iodides was developed utilizing palladium(O) based coupling protocol. This method allowed the preparation of (E)- and (Z)-fluorovinyl phosphonic acid analogs of glucose-6-phosphate that were designed to be machanism-based inhibitors of inositol synthase.

Synthesis of a peptidyl 2,2-difluoro-3-aminopropionate

Abstract Ethyl 3-(benzylamino)-2,2-difluoro-4-methylpentanoate (4) was prepared via a Reformatsky reaction of ethyl bromodifluoroacetate with the imine from isovaleraldehyde and benzylamine. N-Debenzylation of 4 gave amino ester 6, which was coupled to Boc·Ala·Ala·Pro·OH to provide a potential proteinase inhibitor.

(E) and (Z)5′-fluoro olefin carbocyclic nucleosides: effect of olefin geometry on inhibition of s-adenosyl-l-homocysteine hydrolase

Abstract (E) and (Z) 4′,5′-Didehydro-5′-deoxy-5′-fluoroaristeromycin ( 9a and 9b ) were synthesized utilizing the fluoro-Pummerer reaction . Fluoro olefin 9a was a time-dependent inhibitor of S-adenosyl-L- homocysteine hydrolase whereas 9b was a competitive inhibitor. The effects of 9a and 9b on T cell proliferation are presented.

Janus compounds: dual inhibitors of proteinases

Abstract The concept of dual proteinase inhibition has been demonstrated with the preparation of unsymmetrical bis-terephthalamides.

An assay for dihydroorotase using high-performance liquid chromatography with radioactivity detection

An assay for measuring dihydroorotase activity was devised. Radiolabeled substrate and product were separated by high-performance liquid chromatography using a reverse-phase column with ion-pairing, and the radioactivity was quantitated by flow detection.

The specificity of two proteinases that cleave adjacent to arginine, Cl esterase and acrosin, for peptide p-nitroanilide substrates

Relative values of Vmax/Km for hydrolysis of 40 peptide p-nitroanilides catalyzed by human Cl-s and human acrosin are reported. For Cl-s, Ac-Lys(gamma Cbz)-Gly-Arg is the optimum sequence, but 25% of the substrates have (Vmax/Km)rel greater than 0.25 compared to this sequence. The best acrosin substrate tested has the sequence Tos-Gly-Pro-Arg, although (Vmax/Km)rel greater than 0.15 for more than half of the substrates. Proline at P2 is preferred by acrosin. Both enzymes prefer arginine at P1 greater than or equal to 3-fold over lysine and will not accept citrulline. In addition, occupancy of site S3 may yield an increase in Vmax/Km of greater than or equal to 10-fold with either enzyme, but many residues are accepted at S2, S3 and S4. Thus, an acrosin assay using Tos-Gly-Pro-Arg p-nitroanilide as a substrate is more than 20-times as sensitive as existing assays with blocked arginine derivatives.

CIS (1S,3R)-1-(9-ADENYL)-3-HYDROXYCYCLOPENTANE INHIBITS THE RESPITATORY BURST FROM POLYMORPHONUCLEAR LEUKOCYTES AND HAS IN VIVO EFFICACY IN AN ACUTE A ND CHRONIC MODEL OF INFLAMMATION

Abstract The adenine-containing carbocyclic nucleosides 1 and 2 were synthesized in optically active form and have been shown to effectively inhibit interferon-gamma priming of Lewis (LEW/N) rat air pouch-derived PMNs. Compound 2 was also shown to have in vivo activity in a LEW/N rat antigen-induced arthritis model which assesses acute and chronic inflammation.