Histidine, C_{6}H_{9}N_{3}O_{2}, HC===C--CH_{2}·CHNH_{2}·COOH, | | imidazole-amino-propionic N NH acid. \\/ C | H Tryptophane, C_{11}H_{12}N_{2}O_{2}, / \ | |---C--CH_{2}·CHNH_{2}·COOH, indole-amino-propionic acid. | | ║ | | CH \ /\ / N | H As has been said, other amino-acids are being found, from time to time, as additional proteins are examined, or as better methods of examination of the cleavage products of the natural proteins are devised. COMPOSITION OF PLANT PROTEINS The distribution of the different amino-acids in some of the different plant proteins which have been examined in this way is shown in the following table: Letter code for column headings: A = Gliadin (wheat). B = Hordein (barley seed). C = Zein (corn). D = Legumin (vetch). E = Edestin (hemp). F = Globulin (squash seed). G = Amandin (almonds). --------------+-------+-------+-------+-------+-------+-------+------- | A | B | C | D | E | F | G --------------+-------+-------+-------+-------+-------+-------+------- Glycine | 0.02 | 0.00 | 0.00 | 0.39 | 3.80 | 0.57 | 0.51 Alanine | 2.00 | 0.43 | 9.79 | 1.15 | 3.60 | 1.92 | 1.40 Valine | 0.21 | 0.13 | 1.88 | 1.36 | 6.20 | 0.26 | 0.16 Leucine | 5.61 | 5.67 | 19.55 | 8.80 | 14.50 | 7.32 | 4.45 Proline | 7.06 | 13.73 | 9.04 | 4.04 | 4.10 | 2.82 | 2.44 Phenylalanine | 2.35 | 5.03 | 6.55 | 2.87 | 3.09 | 3.32 | 2.53 Aspartic acid | 0.58 | ..... | 1.71 | 3.21 | 4.50 | 3.30 | 5.42 Glutamic acid | 42.98 | 43.19 | 26.17 | 18.30 | 18.84 | 12.35 | 23.14 Serine | 0.13 | ? | 1.02 | ? | 0.33 | ? | ? Cystine | 0.45 | ? | ? | ? | 1.00 | 0.23 | ? Tyrosine | 1.20 | 1.67 | 3.55 | 2.42 | 2.13 | 3.07 | 1.12 Arginine | 3.16 | 2.16 | 1.55 | 11.06 | 14.17 | 14.44 | 11.85 Histidine | 0.61 | 1.28 | 0.43 | 2.94 | 2.19 | 2.63 | 1.58 Lysine | ..... | ..... | ..... | 3.99 | 1.65 | 1.99 | 0.70 Tryptophane |present|present| absent|present|present|present|present Ammonia | 5.11 | 4.87 | 3.64 | 2.12 | 2.28 | 1.55 | 3.70 +-------+-------+-------+-------+-------+-------+------- | 71.46 | 78.16 | 85.27 | 62.65 | 82.38 | 55.77 | 59.00 --------------+-------+-------+-------+-------+-------+-------+-------