A non-essential amino acid for human development. A major intracellular source of one carbon units for de novo purine synthesis. Found in the active site of serine proteases such as trypsin. Isoln from the silk protein, sericine: E. Cramer, Prakt. Chem. 96, 76 (1865). Structure and synthesis as dl-form: E. Fischer, H. Leuchs, Ber. 35, 3787 (1902). Early chemistry and biochemistry: Amino Acids and Proteins, D. M. Greenberg, Ed. (Charles C. Thomas, Springfield, IL, 1951) 950 pp., passim; J. P. Greenstein, M. Winitz, Chemistry of the Amino Acids vols 1-3 (John Wiley and Sons, Inc., New York, 1961) pp. 2202-2237, passim. Enzymatic determn in biological samples: R. D. Hurst et al., Anal. Biochem. 117, 339 (1981). Synthetic reviews: K. Toi in Synthetic Production and Utilization of Amino Acids, T. Kaneko et al., Eds. (Halsted, New York, 1974) pp 187-195; of dl-forms: L. Bassignani et al., Ber. 112, 148-160 (1979). Review of role in enzyme active sites: B. S. Hartley, Ann. N.Y. Acad. Sci. 227, 438-445 (1974); J. Lamotte-Brasseur et al., Biotechnol. Genet. Eng. Rev. 12, 189-230 (1994). Review of metabolism: K. Snell, D. A. Fell, Adv. Enzyme Regul. 30, 13-32 (1990).
Presence in rat brain: A. Hashimoto et al., FEBS Lett. 296, 33 (1992). As synaptic modulator: M. J Schell et al., Proc. Natl. Acad. Sci. USA 92, 3948 (1995).