¹⁵N NMR spectroscopy 31—preliminary study on the insulin‐a chain (bunte salt form)

Abstract

The Bunte salt derivative was prepared from bovine insulin-A isolated from natural sources, and was purified by chromatography. Natural abundance 40.55 M H z "N NMR spectra were measured in water and dimethyl sulphoxide. The latter solvent gave the best resolution, and 20 of the 22 possible amide nitrogen signals were detected. Several model oligopeptides were also measured and their usefulness for assignments is discussed.

Interactions of ions with the surface receptor of the azobenzene-containing bilayer membrane. Discrimination, transduction, and amplification of chemical signals

“…Relevant bond distances (in pm): Pt-Pl, 228.8 (3); Pt-P2, 229.4 (3); Pt-P3, 221.8 (3); P3-C46, 165 (1); P3-C37, 182 (1); C46-C47, 156 (2); C46-C53, 151 (2); Pl-Cl, 187 (1); P1-C7, 183 (1); P1-C13, 185 (1); P2-C19, 182 (1); P2-C25, 182 (1); P2-C31, 180 (1). Relevant bond angles (in degrees): Pl-Pt-P3, 120.6 (1); P2-Pt-Pl, 121.9 (1); P2-Pt-P3, 117.3 (1); Pt-P3-C46, 133.3 (5); Pt-P3-C37, 118.2 (3); C46-P3-C37, 108.5 (5); C53-C46-P3, 122.6 (8); C53-C46-C47, 133.3 (8); C47-C46-P3, 124.0 (8). (12) Hopkinson, M. J.; Kroto, H. W,; Nixon, J. F.; Simmons, N. P. C. J.…”

“…Natural abundance 15N spectra of biopolymers have single-site resolution only when very concentrated large samples are extensively signal averaged in a high-field spectrometer. 4,5 There are several advantages to solid-state 15N NMR experiments. The sensitivity due to cross polarization of the 15N magnetization from the protons is increased over that from 15N sampling pulses because of the larger amount of 15N magnetization developed per transient and the ability to recycle the experiment according to the generally short ]H 77 s rather than the long 15N Txs.6 The observed nuclear Overhauser enhancement varies with reorientation rates in solution and can completely eliminate signals in spectra of biopolymers, but is avoided in the cross-polarization experiment.…”