Title: Proline
CAS Registry Number: 147-85-3
CAS Name: L-Proline
Additional Names: Pro; P; (S)-2-pyrrolidinecarboxylic acid
Molecular Formula: C5H9NO2
Molecular Weight: 115.13
Percent Composition: C 52.16%, H 7.88%, N 12.17%, O 27.79%
Literature References: Non-essential amino acid for human development. Only imino acid of the 20 amino acids commonly found in proteins. Shows cis-trans isomerism. First synthesized: R. Willstätter, Ber. 33, 1160 (1900); prior to identification in casein: E. Fischer, Ber. 34, 454 (1901). Named in 1904 by Fischer. 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. 2178-2201, passim. Stereospecific synthesis: S. L. Titouani et al., Tetrahedron 36, 2961 (1980). HPLC determn: A. Carisano, J. Chromatogr. 318, 132 (1985). HPLC separation of cis-trans isomers of peptides: S. Friebe et al., ibid. A 661, 7 (1994). Review of biosynthesis and degradation: E. Adams, L. Frank, Annu. Rev. Biochem. 49, 1005-1061 (1980). Review of effects on protein structure and biological function: A. Yaron, F. Naider, Crit. Rev. Biochem. Mol. Biol. 28, 31-81 (1993); G. Vanhoof et al., FASEB J. 9, 736-744 (1995).
Properties: Flat needles from alcohol + ether, prisms from water, dec 220-222°. [a]D23.4 -85.0°; [a]D20 -52.6° (c = 0.57 in 0.50N HCl); [a]D20 -93.0° (c = 2.42 in 0.6N KOH). pI 6.30. pK1 1.99; pK2 10.60. Soly in 100 ml water: 127.4 g at 0°; 162.3 g at 25°; 206.7 g at 50°; 239 g at 65°. Sol in alcohol 1.55% at 35°. Insol in ether, butanol, isopropanol.
pKa: pK1 1.99; pK2 10.60
Optical Rotation: [a]D23.4 -85.0°; [a]D20 -52.6° (c = 0.57 in 0.50N HCl); [a]D20 -93.0° (c = 2.42 in 0.6N KOH)
Derivative Type: DL-Form
CAS Registry Number: 609-36-9
Properties: Monohydrate, crystals, mp 190° (when anhydr, dec 205°). Sol in water, alc; sparingly sol in acetone, chloroform, benzene; insol in ether.
Melting point: mp 190° (when anhydr, dec 205°)
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