The discovery and optimization of hexahydro-2H-pyrano[3,2-c]quinolines (HHPQs) as potent and selective inhibitors of the mitotic kinesin-5

Parameswaran

Journal of Biological Chemistry

et al. 2011

The human Eg5 (HsEg5) protein is unique in its sensitivity to allosteric agents even among phylogenetic kin. For example, S-trityl-L-cysteine (STC) and monastrol are HsEg5 inhibitors that bind to a surface pocket created by the L5 loop, but neither compound inhibits the Drosophila Kinesin-5 homologue (Klp61F). Herein we ask whether or not drug sensitivity can be designed into Klp61F. Two chimeric Klp61F motor domains were engineered, bacterially expressed, and purified to test this idea. We report that effector binding can elicit a robust allosteric response comparable with HsEg5 in both motor domain chimeras. Furthermore, isothermal titration calorimetry confirms that the Klp61F chimeras have de novo binding affinities for both STC and monastrol. These data show that the mechanism of intramolecular communication between the three ligand binding sites is conserved in the Kinesin-5 family, and reconstitution of a drug binding cassette within the L5 pocket is sufficient to restore allosteric inhibition. However, the two compounds were not equivalent in their allosteric inhibition. This surprising disparity in the response between the chimeras to monastrol and STC suggests that there is more than one allosteric communication network for these effectors.The Kinesin-5 family of motor proteins plays a conserved role in the morphogenesis of the mitotic spindle. In particular, human Eg5 kinesin (HsEg5) 2 forms a homotetramer that is capable of cross-linking adjacent microtubule bundles during spindle formation and is essential for mitotic progression. High-throughput screens for small chemical inhibitors of mitosis have often yielded compounds that target this kinesin in particular. At the time of their discovery, these compounds represented the only known antimitotic compounds that did not directly affect cellular microtubule assembly or function and constituted an entirely new class of potential anticancer compounds. Important for our purposes, they also serve as tools to explore fundamental questions about motor protein function.To date, small chemical inhibitors have been discovered that bind to at least three different sites within the motor domain of HsEg5 (1-4). The most highly explored allosteric site is a single pocket whose absolute location was defined by xray crystallography (for examples, see . This site is formed by the ␣2 and ␣3 helices and capped by the L5 loop. This L5 pocket is on the surface of the motor domain and is ϳ12 Å and 22 Å from the nucleotide binding site and microtubule (MT)-binding site, respectively.Interactions of the L5 loop are at the crux of long distance, allosteric communication with the active site and the MTbinding site. The biochemical role of the L5 loop has been confirmed by kinetic measurements and mutagenesis efforts. Mutations throughout the loop result in varying degrees of inhibition of basal rates and MT-stimulated ATPase rates (3,7,(12)(13)(14)(15). Not limited in its effects upon the orthosteric site, a dihydropyrimidine derivative, monastrol, has been shown to affect h...

mentioning

confidence: 99%

Loop 5-directed Compounds Inhibit Chimeric Kinesin-5 Motors

Parameswaran

Journal of Biological Chemistry

et al. 2011

“…Rewardingly, Sc III -USY gave the expected adduct 5 a in low to high yields depending on the solvent used (entries 6-10). A slow but clean transformation was observed in apolar or slightly polar solvents and despite heating, the adduct 5 a was isolated with modest yields (entries [6][7]. Surprisingly, in more polar solvents, such as THF, the reaction was even lower although the conversion was similar (entry 8 vs. 6-7).…”

Section: Resultsmentioning

confidence: 95%

“…[3] Among them, tetrahydroquinolines exhibit the largest range of activities. [4] They are not only used or developed as antibacterial agents, [5] as antitumor agents, [6] as HIV protease inhibitors, [7] as therapeutic agents for i.a. allergic diseases triggered by prostaglandin (CRTH2 inhibitors; Scheme 1), [8] or for antiemetic and analgesic effects through activation of cannabinoid receptors (Levonantradol, Scheme 1), [9] but also as compounds for altering the lifespan of eukaryotic organisms [10] or imaging G protein-coupled estrogen receptors.…”

Section: Introductionmentioning

confidence: 99%

Scandium(III) Zeolites as New Heterogeneous Catalysts: [4+2]Cyclocondensation of in situ Generated Aryl Imines with Alkenes

Olmos

Sommer

Pale

2011

Chemistry A European J

Scandium(III)-exchanged zeolite was used as heterogeneous ligand-free catalysts for the [4+2]cyclocondensation of amines and aldehydes with alkenes through the in situ formation of imines. Such catalysts offered a versatile, efficient, and highly regio- and stereoselective synthesis of tetrahydroquinoline derivatives. These catalysts exhibited a wide scope and compatibility with functional groups. They are very simple to use, easy to remove (by simple filtration), and they are recyclable (up to three times without loss of activity).

“…When the same conditions were used with 2-chloro 3-amino pyridine, instead of the expected product (10), by-product (9) was produced in 23% yield (Scheme 2). The mechanism for the formation of 9 involves the initial generation of intermediate (6), then imine intermediate (6) is transformed into enamine intermediate (7). As seen in Scheme 3, by-product (9) was obtained from enamine (7) which with a second mol of methyl pyruvate forms an intermediate alcohol by a 1,2-addition which subsequently cyclises to the product (9) (Scheme 3).…”

mentioning

confidence: 99%

“…They can be readily transformed to 1,2,3,4-tetrahydroquinolines [3][4] and quinolines [5][6] which are of great value in medicinal chemistry. [7][8] In the literature, numerous methods describe the synthesis of 1,2-dihydroquinolines. Typically aryl amines were reacted with a range of different compounds such as ketones, 9 α,β-unsaturated ketones 10 , 2,2-dimethoxy propane, 11 aldehyde, 12 alkynes, 13 alcohol, 14 glycerine, 15 α-ketoester [16][17] in the presence of Lewis acid or Brønsted acid catalysts.…”

Section: Introductionmentioning

confidence: 99%

An efficient method for the preparation of 2,2,4-trisubstituted 1,2-dihydroquinolines using catalytic amount Bi(OTf)3 as catalyst

Gültekin¹,

Frey²

2012

Arkivoc

Substituted 1,2-dihydroquinolines have been synthesised from substituted anilines and methyl pyruvate using catalytic amounts of commercially available Bi(OTf) 3 as a catalyst under microwave-assisted conditions. This method is simple, easy to work up, inexpensive, with a broad substrate scope and short reaction times. The reaction provides 1,2-dihydroquinolines (19 examples) in good yields (34-97% yields).