emission tomography (PET) studies and 75Se-labeled Sec (half-life of 75Se = 118.5 days) in specific radiolabeling, facilitation of phase determination by multiwavelength anomalous diffraction in X-ray crystallography of proteins by introducing Sec alone, or Sec together with selenomethionine (SeMet), and incorporation of the stable 77Se isotope, which has a nuclear spin of and can be used for high-resolution NMR, among others. See also Pyrrolysine, another amino acid not in the basic set of 20. Selenomethionine, another selenium-containing amino acid, which is randomly substituted for methionine. References Further reading External links For the first time a Uruguayan scientist finds selenocysteine in fungi Amino acids Proteinogenic amino acids Selenols