Leucine-enkephalin (lenk) is a five amino acid peptide (Tyr1-Gly2-Gly3-Phe4-Leu5) that acts as an opiate agonist in the mammalian brain. Lenk possesses a great deal of conformational flexibility in solution, which allows lenk to interact with a variety of receptors in the brain. Knowledge about the motion of lenk in solution can provide a better understanding of opiate agonist systems in the mammalian brain and body, and has potential to aid in the development of novel opiate agonists.Nuclear Magnetic Resonance (NMR) spin-lattice relaxation experiments will be used to characterize the dynamics of lenk in solution. 13C labeling at the �-carbon of phenylalanine will allow the motion of the phenylalanine side chain to be characterized through spin-lattice relaxation NMR experiments. Lenk will be synthesized via solid-phase peptide synthesis using Fmoc groups as temporary protection for a-amino groups. 13C-labeled phenylalanine has been Fmoc protected and will be used to synthesize the peptide.Spin-relaxation NMR experiments will be performed to understand the motion of the phenylalanine side arm of lenk in solution. In a strong static magnetic field B0 a nucleus with a non-zero spin (such as 1H or 13C) will have a magnetic moment that is either parallel (a) or antiparallel (�) to the magnetic field. The parallel orientation is lower in energy and is more populous than the antiparallel orientation; because of this unequal distribution of populations a macroscopic magnetization MO is observed. When a pulse is applied to a system undergoing NMR the system redistributes its energy in a process called relaxation as it returns to equilibrium, the relaxation times can be determined from these experiments. Relaxation times provide information about the rates and types of conformational changes experienced by leucine-enkephalin in solution. If these experiments are successful the tyrosine residue will also be examined using the same procedures and experiments.

Synthesis of <sup>13</sup>C-labeled leucine-enkephalin and NMR relaxation studies of the phenylalanine side chain of leucine-enkephalin

247th National Meeting (2014)

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Synthesis of 13C-labeled leucine-enkephalin and NMR relaxation studies of the phenylalanine side chain of leucine-enkephalin

Synthesis of ¹³C-labeled leucine-enkephalin and NMR relaxation studies of the phenylalanine side chain of leucine-enkephalin