Zinc is an essential cofactor for type I isopentenyl diphosphate:dimethylallyl diphosphate isomerase

Isopentenyl diphosphate (IPP) isomerase catalyzes the interconversion of IPP and dimethylallyl diphosphate (DMAPP). This is an essential reaction in the mevalonate pathway for biosynthesis of isoprenoid compounds. A crystal structure of Escherichia coli type I IPP isomerase shows a his3glu2 octahedral metal binding site (Durbecq, V. et al. EMBO, 2001, 20, 1530-1537). A metal ion analysis of recombinant E. coli type I IPP isomerase purified from metal-free buffer or buffer containing 10 muM ZnCl2 and 10 muM MnCl2 indicated that the protein contained one atom of Zn2+ per molecule. The metal content and the activity of the enzyme did not change when dialyzed for 6 h against metal-free buffer but rapidly decreased upon dialysis against buffer containing o-phenanthroline. Structural and catalytic roles for Zn2+ are discussed.     

Synthesis and structural studies of hydrophilic mesocyclic trithioethers

The functionalized mesocyclic trithioethers, 1,4,7-trithiacyclodecane-9,9-dimethanol (10S3-diMeOH), 9 -methyl-1, 4, 7 - trithiacyclodecane - 9 -carboxylic acid (Me-10S3-acid), 1,4,7-trithiacycloundecane-9,10-diol (dihydroxy-11S3), 1,5,9-trithiacyclododecane-3,3-dimethanol (12S3-diMeOH), 3-methyl-1,5,9-trithiacyclododecane-3-carboxylic acid (Me-12S3-acid), and 1 , 5 , 9 - trit hiacyclo tride cane -11 , 12 - diol ( dihydroxy - 13S3), have been synthesized using the cesium dithiolate technique. The single-crystal X-ray structure has been determined for 3-methyl-1,5,9-trithiacyclododecane-3-carboxylic acid. The compound crystallizes in the monoclinic space group P2₁/n, with a = 9.513(2) Å, b = 5.706(1) Å, c = 25.70(1) Å, β = 96.50(1)°, Z = 4, and R = 0.075. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:123–128, 1998     

A role for fucose alpha(1-2) galactose carbohydrates in neuronal growth

We report a fucose alpha(1-2) galactose-mediated pathway for the modulation of neuronal growth and morphology. Our studies provide strong evidence for the presence of Fucalpha(1-2)Gal glycoproteins and lectin receptors in hippocampal neurons. Additionally, we show that manipulation of Fucalpha(1-2)Gal-associated proteins using small-molecule and lectin probes induces dramatic changes in neuronal morphology. These findings may provide a novel pathway to stimulate neuronal growth and regeneration.     

Solid phase deprotection of 2-nitrobenzenesulfonamides: synthesis of simple 2-(alkylamino)-pyrroles

The 2-nitrobenzenesulfonamide cleavage using a solid-phase thiophenolate reagent gives simple 2-(alkylamino)-pyrroles without the presence of the competing nucleophilic substitution product.     

Optimizing State Patrol Manpower Allocation

One of the most difficult tasks of state highway patrol administrators is allocation of manpower; i.e. determining the most effective level of operational manpower for patrol tasks. Typically, administrators resolve the allocation problem by relying on prior statistical data and by employing subjective analysis. In general, only limited systematic analyses have been applied to the problem. This paper presents an integer goal programming model for allocating highway patrolmen to road segments within a patrol region. The model is demonstrated via a case example of the Nebraska State Patrol. The results of the model are valuable to the patrol administrator for considering departmental goals and priority structure, in addition to available historical data, in the assignment of state patrol manpower.     

Search for neutrino-produced magnetic monopoles in a bubble chamber exposure

J. Schwinger has suggested that magnetically charged particles could be produced via a magnetically charged intermediate boson process similar to the mechanism sometimes envisioned for double muon production by neutrinos. A search for magnetic monopole production by neutrinos has been made by reexamining the CERN heavy liquid bubble chamber pictures obtained during the neutrino exposures of 1963 and 1967. Five different searches were made for events which contained a free monopole with and without target nucleus excitation, and for bound monopoles which deexcited by photon emission. No events were found. Neutrino monopole production cross-section limits are given.     

Investigation of gas phase ion structure for proline-containing b2 ion

Unusual fragmentation was observed for doubly charged VPDPR in which cleavage C-terminal to proline and N-terminal to aspartic acid yielded b(2) (+ a(2))/y(3) complementary ions. This unique fragmentation is contradictory to trends previously established by statistical analysis of peptide tandem mass (MS/MS) spectra. Substitution of alanine for aspartic acid (i.e., VPAPR) did not change the fragmentation, indicating the cleavage was not directed by aspartic acid. Fragmentation patterns for VPAPR and V(NmA)APR (NmA = N-methyl alanine) were compared to determine whether conformational constraints from proline's cyclic side-chain contribute to b(2) ion formation. While both peptide sequences fragmented to yield b(2)/y(3) ions, only VPAPR produced a(2) ions, suggesting the VP b(2) ion is structurally different from the V(NmA) b(2) ion. Instead, the V(NmA) b(2) ion was accompanied by an ion corresponding to formal loss of 71. The suspected structural differences were confirmed by isolation and fragmentation of the respective b(2) ions (i.e., MS(3) spectra). Evidence supporting a diketopiperazine structure for the VP b(2) ion is reported. Fragmentation patterns for the VP b(2) ion and a synthetic VP diketopiperazine showed great similarity. N-terminal acetylation of VPAPR prevented the formation of the VP b(2) ion, presumably by blocking nucleophilic attack by the N-terminal amine on the carbonyl oxygen of the protonation site. Acetylation of the N-terminus for V(NmA)APR did not prevent the formation of the V(NmA) b(2) ion, indicating the V(NmA) b(2) ion has a structure, presumably that of an oxazolone, which requires no attack by the N-terminus for formation. Finally, high-resolution, accurate mass measurements determined that the V(NmA) (b(2)-71) ion results from losing a portion of valine from oxazolone V(NmA) b(2) ion, rather than cross-ring cleavage of the alternate diketopiperazine.