| In addition to histidine and biotin, the top agar contained minimal tryptophan to support E.coli growth. |
| The active site of trypsin involves a catalytic triad consisting of the amino acids serine, histidine and aspartic acid. |
| The most prevalent amino acid is cysteine with other major ones including tyrosine, histidine, lysine and arginine. |
| Systems for sensing specific sugars, such as galactose or maltose, or specific amino acids, such as histidine or proline, also are present. |
| The mixture was later solidified by means of a surface agar solution containing traces of histidine and biotin. |
| The essential amino acids are histidine, tryptophan, threonine, valine, phenylalanine, leucine, methionine, lysine, and isoleusine. |
