Synthesis and Characterization of Organohalogens

Organohalogens were custom synthesized as described in the Supporting Information (SI) or as described previously,^{21 (link),28 (link)} isolated from marine sponges^{38 (link)} or purchased [pyrrole (24), ethyl-4-bromopyrrole-2-carboxylate (27) and 2,3-dibromo-N-methylmaleimide (28)] from SigmaAldrich (St. Louis, MO). Names and structures for the compounds tested are summarized in Table SI1. All the HOCs were dissolved in dry DMSO (10 mM) and stored at −80 °C. Phenylmethylsulfonyl fluoride (PMSF), leupeptin hydrochloride, Mg-ATP, phosphocreatine, creatine phosphokinase, phosphoenolpyruvate, pyruvate kinase/lactic dehydrogenase, Na₂ATP, NADH were purchased from Sigma-Aldrich. Arsenazo III was purchased from Santa Cruz Biotechnology (Dallas, TE). Ryanodine was purchased from Ascent Scientific (Cambridge, MA) and dissolved in 100% ethanol and stored at 4 °C until use. [³H]Ryanodine (specific activity: 56.6 Ci/ mmol) was obtained from PerkinElmer (Santa Clara, CA).