Alanine fasting state

Fig. 42.3. Interorgan amino acid exchange after an overnight fast. After an overnight fast (the postabsorptive state), the utilization of amino acids for protein synthesis, for fuels, and for the synthesis of essential functional compounds continues. The free amino acid pool is supported largely by net degradation of skeletal muscle protein. Glutamine and alanine serve as amino group carriers from skeletal muscle to other tissues. Glutamine brings NH4 to the kidney for the excretion of protons and serves as a fuel for the kidney, gut, and cells of the immune system. Alanine transfers amino groups from skeletal muscle, the kidney, and the gut to the liver, where they are converted to urea for excretion. The brain continues to use amino acids for neurotransmitter synthesis.

The solid-state NMR homonuclear decouphng sequences in the DUMBO family have been shown to be effective at ultra-fast MAS rates of up to 65 kHz. The sequences were apphed to model compounds glycine and [2-13C]-L-alanine as well as to the dipeptide p-L-Asp-L-Ala in windowed and continuous phase-modulated versions. They were shown to achieve especially impressive resolution when implemented in a 2D constant-time experiment. At 65 kHz MAS, H resolution using homonuclear decoupling was found to be similar to that obtained at lower MAS rates, whereas the spectral sensitivity was improved by a factor of 5 over homo-nuclear-decoup led spectra at 10 kHz MAS. 

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