Solid state NMR of isotope labelled murine fur: a powerful tool to study atomic level keratin structure and treatment effects.

We have prepared mouse fur extensively ¹³ C, ¹⁵ N-labelled in all amino acid types enabling application of 2D solid state NMR techniques which establish covalent and spatial proximities within, and in favorable cases between, residues. ¹³ C double quantum-single quantum correlation and proton driven spin diffusion techniques are particularly useful for resolving certain amino acid types. Unlike 1D experiments on isotopically normal material, the 2D methods allow the chemical shifts of entire spin systems of numerous residue types to be determined, particularly those with one or more distinctively shifted atoms such as Gly, Ser, Thr, Tyr, Phe, Val, Leu, Ile and Pro. Also the partial resolution of the amide signals into two signal envelopes comprising of α-helical, and β-sheet/random coil components, enables resolution of otherwise overlapped α-carbon signals into two distinct cross peak families corresponding to these respective secondary structural regions. The increase in resolution conferred by extensive labelling offers new opportunities to study the chemical fate and structural environments of specific atom and amino acid types under the influence of commercial processes, and therapeutic or cosmetic treatments.
Competing Interests: Compliance with ethical standards Conflicts of interest None of the authors have any conflicts of interest in regard to this work. Human and animal rights No human subjects or tissues were used. All animal procedures complied with institutional ethical guidelines, and the U. K. Animals (Scientific Procedures) Act 1986.