Tris 2 carboxyethyl phosphine tcep hydrochloride

For synthesis of FNA tether following reagents were purchased from Glen Research (Sterling, VA): biotin-linked CPG (3′-PROTECTED Biotin Serinol CPG; 20-2993), Spacer 18 phosphoramidite (18-O Dimethoxytritylhexaethyleneglycol, 1-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite, 10–1918), DBCO-dT-CE phosphoramidite (5′-Dimethoxytrityl-5-[(6-oxo-6-(dibenzo[b,f]azacyclooct-4-yn-1-yl)-capramido-N-hex-6-yl)-3-acrylimido]-2′-deoxy-Uridine, 3′-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite, 10-1539), Thiol-Modifier C6 S-S, (1-O-Dimethoxytrityl-hexyl-disulfide,1′-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite, 10-1936).
The azide-labeled Aβ (14–23) peptide [K(N₃)HQKLVFFVAED] was synthesized and purified by Peptide 2.0 Inc. (Chantilly, VA). Tris (2-carboxyethyl) phosphine (TCEP) hydrochloride was from Hampton Research (Aliso Viejo, CA). N-(γ-Maleimidobutyryloxysuccinimide ester) GMBS was from Pierce Biotechnology (Grand Island, NY). Streptavidin protein was purchased from Sigma-Aldrich (St. Louis, MO). 1-(3-aminopropyl) silatrane (APS) was synthesized as previously described.⁴³ All other reagents or solvents were purchased from Sigma Aldrich (St. Louis, MO).

All reagents used for the synthesis of the FNA tether were purchased from Glen Research (Sterling, VA): spacer 18 phosphoramidite (18-O Dimethoxytritylhexaethyleneglycol, 1-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite, 10–1918, Glen Research), DBCO-dT-CE phosphoramidite (5′-Dimethoxytrityl-5-[(6-oxo-6-(dibenzo[b,f]azacyclooct-4-yn-1-yl)-capramido-N-hex-6-yl)-3-acrylimido]-2′-deoxy-Uridine, 3′-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite, 10-1539-xx, Glen Research), Thiol-Modifier C6 S-S, (1-O-Dimethoxytrityl-hexyl-disulfide,1′-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite, 10-1936-xx, Glen Research), biotin CPG (3′-Protected Biotin Serinol CPG; #20-2993; GlenResearch). The azide-labeled Aβ(14–23) peptide [K(N3)HQKLVFFVAED] was synthesized and purified by Peptide 2.0 company (VA, USA). Tris (2-carboxyethyl) phosphine (TCEP) hydrochloride was from Hampton Research (Aliso Viejo, CA). Heterobifunctional MAL-PEG₃₄₀₀-SVA was from Laysan Bio (Arab, AL). N-(g-Maleimidobutyryloxysuccinimide ester) GMBS was from Pierce Biotechnology (Grand Island, NY). Streptavidin-thiol was from Protein Mods (Madison, WI) and 1-(3-aminopropyl) silatrane (APS) was synthesized as previously described [15 (link)]. All other reagents or solvents were purchased from Sigma–Aldrich.

Recombinant bovine calmodulin (lyophilized powder, C4874) was from Sigma-Aldrich (St. Louis, MO). Exenatide (lyophilized powder, AS-24464, 1HGEGTFTSDLSKQMEEEAVRLFIEWLKNGGPSSGAPPPS³⁹-NH₂) and adrenocorticotropic hormone (ACTH) peptide (lyophilized powder, AS-20619, ¹⁸RPVKVYPNGAEDESAEAFPLEF³⁹) were from Anaspec (Fremont, CA). The concentrations were determined by UV absorption at 280 nm using extinction coefficients calculated based on amino acid sequence. Sequencing grade Glu-C endoprotease was from Promega (V1651; Madison, WI). Tris(2-carboxyethyl)phosphine (TCEP) hydrochloride was from Hampton Research (Al Jodo, CA). Dithiothreitol (DTT) was from Acros Organics (New Jersey, NJ). ¹⁸O water (normalized, 97% – 98% atom percentage) was from Icon Stable Isotopes (Summit, NJ). All aqueous solutions were prepared with MilliQ purified water. All chemicals used were reagent grade or better. The pH of all solutions was determined by EMD Colorphast pH strips with an accuracy of 0.5 unit.