Long chain amines and long chain ammonium salts as novel inhibitors of dynamin GTPase activity Timothy A. Hill, a Luke R. Odell, a Annie Quan, b Ruben Abagyan, c Gemma Ferguson, a Phillip J. Robinson b,  and Adam McCluskey a, * a Advanced Synthetic Materials Group, Chemistry Building, School Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia b Children’s Medical Research Institute, 214 Hawkesbury Road, Westmead, NSW 2145, Australia c Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, TCP-28, La Jolla, CA 92037, USA Received 29 September 2003; accepted 29 March 2004 Abstract—We examined a number of ligands with the view of inhibiting the GTPase activity of dynamin. Dynamin contains a pleckstrin homology (PH) domain that interacts with lipids. We report a series of simple lipid-like molecules that display moderate inhibitory activity. Inhibitory activity is linked to chain length and quaternarization of the terminal amine. A change in the counterion, Cl versus Br or I, had little effect on potency. However, introduction of a hydrophobic collar proximal to the charged site was beneficial to dynamin GTPase inhibitory action. The most potent compound was myristoyl trimethyl ammonium bromide (MTMAB, IC 50 3.15 lM). Ó 2004 Elsevier Ltd. All rights reserved. The uptake and recycling of extracellular material by mammalian cells proceeds via endocytosis. 1–3 Crucial to this activity is the formation of a myriad of different sized vesicles––from the large phagosomes and the smaller clathrin-coated vesicles to tiny synaptic vesicles. Endocytic mechanisms are subservient to a variety of cellular functions including the uptake of cellular nutrients, regulation of cell-surface receptor expression and signaling, antigen presentation and maintenance of synaptic transmission. Although there are a variety of endocytic pathways, two have been biochemically well characterized, rapid synaptic vesicle endocytosis (SVE) that follows vesicle exocytosis in nerve terminals. SVE serves to retrieve empty synaptic vesicles for later refilling. 4;5 The second is receptor-mediated endocytosis (RME) which is initiated upon ligand binding to cell surface receptors and occurs via clathrin-coated pits in all cells. 4 SVE and RME perform distinct func- tional roles and share the same underlying protein machinery, but they may use distinct isoforms of the same protein. Alzheimer’s disease, Huntington’s disease, Stiff-person syndrome, Lewy body dementias, and Niemann-Pick type C disease are illustrative of human pathological conditions within which defects in endocytosis have been implicated. 6–9 Endocytic pathways are also utilized by viruses, toxins and symbiotic microorganisms to gain entry into cells. Dynamin was the first of a new family of dynamin-like GTP-binding proteins that share similar GTPase domains. This domain is crucial for vesicle fission, and consequently represents an important step in the endo- cytic pathway. 4;10 There are three dynamin genes, with dynamin I in neurons, II being ubiquitously expressed and III in neurons and testes. 5;11 All dynamins have four main domains, which are potential drug targets. The GTPase domain has an unusually low affinity for GTP (10–25 lM) and extremely high turnover rates compared with other GTPases. This activity is required for vesicle fission. 11;12 The crystal structure of this domain of dynamin from Dictyostelium was recently *Corresponding author. Fax: +61-249-21-5472; e-mail: adam. mccluskey@newcastle.edu.au   E-mail: phrobins@mail.usyd.edu.au 0960-894X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmcl.2004.03.096 Bioorganic & Medicinal Chemistry Letters 14 (2004) 3275–3278