Beilstein Biochemical Preparations

Crystallise GABA from aqueous EtOH or MeOH/Et20. Also crystallise it by dissolving it in the least volume of H2O and adding 5-7 volumes of absolute EtOH. [Shtrman Biochemical Preparations 4 91 7955, cb Witt Org Synth Coll Vol II 25 1943, Beilstein 4 III 1316,4 IV 2600.]... 

S-P-Aminoisobutyric acid (a-methyl-P-alanine) [10569-72-9] M 103.1, m 176-178 , 178-180 , 181-182 ,R-f-)- isomer [144-90-1] m 183 , [a] -21 (c 0.43, H2O), pKEst(i) 3.7, pKEst(2) 10.2. RS -p-Aminoisobutyric add forms colourless prisms by crystallisation from hot H2O which are powdered and dried in vacuo. The purity is checked by paper chromatography (Whatman 1) using ninhydrin spray to visualise the amino acid Rp values in 95% MeOH and -PrOH/5N HCOOH (8 2) are 0.36 and 0.50 respectively. [Kupiecki Coon Biochemical Preparations 7 20 1960, Pollack J Am Chem Soc 65 1335 1943.] The R-enantiomer, isolated from iris bulbs or human urine, crystallises from H2O and subUmes in vacuo [Asen et al. J Biol Chem 234 343 1959]. The RS-hydrochloride crystallises from EtOH/Et20 with m 128-129° (also 130°) [Bohme et al. Chem Ber 92 1258,1260,1261 7959]. [Beilstein 4 IH 1330.]... 

Recrystallise the sulfate by dissolving ( lg) in H2O (lOmL), and adding with stirring 0.5 to 1.0 volumes of 95% EtOH whereby crystals separate. These are collected, washed with Me2CO/EtOH (1 1) and dried over P2O5 in a vacuum. [Hunt Thompson Biochemical Preparations 13 416 1971, Feacon Bell Biochem J 59 221 1955, Beilstein 4 III 1636,4 IV 3188.]... 

Edsall Bull Soc Chim Fr 40 1763 1958, du Vigneaud Miller Biochemical Preparations 2 87 1952, Greenstein Winitz The Chemistry of the Amino Acids J. Wiley, Vol 2 p 1523 1961, Beilstein 4 IV 3165.]... 

Likely impurities are dZ-methionine sulfone and dZ-methionine. CrystalUse the sulfoxide by dissolving it in hot H2O and adding excess EtOH. [Lepp Dunn Biochemical Preparations 4 SO 1955, Micheel Schmitz Chem Ber 72 518 1939, Beilstein 4 III 1650, 4 IV 3192.]... 

PO4H). It is characterised by conversion to the acridine salt by addition of alcoholic acridine (1. Ig in 50mL), filtering off the yellow salt and recrystallising from H2O. The salt has m 215°(dec), X ax 259nm (e 15,400) in H2O. [Baddiley Todd J Chem Soc 648 1947, 582 1949, cf LePage Biochemical Preparations 1 1 1949, Martell Schwarzenbach Helv Chim Acta 39 653 1956], [Beilstein 26 III/IV 2369.]... 

Phosphoenolpyruvic acid tris(cyclohexylamine) sait [35556-70-8] M 465.6, m 155-180 (dec). Recrystallise it from aqueous Mc2CO and dry it in a vacuum. At 4° it is stable for >2 years and has IR at 1721cm (C=0). [Wold Ballou J Biol Chem 221 301 1957, Clark Kirby Biochemical Preparations 11 103 7966 for the monocyclohexylamine salt, Beilstein 12 IV 8.]... 

L(+)-Lactic acid (S (+)-2-hydroxypropionic acid) [79-33-4] M 90.1, m 52.8 , b 105 /0.1mm, [a] g +3.82 (H2O), pK 3.83. Piuify lactic acid by fractional distillation at O.ltmn pressitre, followed by fraction crystallisation from diethyl ether/isopropyl ether (1 1, dried with sodium). [Borsook et al. J Biol Chem 102 449 7955.] The solvent mixtrrre, benzene/diethyl ether (1 1) containing 5% petroleum ether (b 60-80°) has also been used. Qmv Biochemical Preparations Z6 1953, Beilstein 3IV 633.]... 

Ciystallise it from MeOH/EtOH (1 1). Separation from normal a//o-isomer can be achieved by crystallisation of the copper salts [see Levine Biochemical Preparations 8 114 1961]. Separation from proline is achieved via the ciystalline picrate, CdCl2, or acid ammonium rhodanate salts [see Greenstein Winitz The Chemistry of the Amino Acids J. Wiley, Vol 3 p 2182 1961, Kapfhammer Mohn Z Physiol Chem 306 76 1956], [Beilstein 22/5 V 7.]... 

---