“…[21] The highest activity was observed with putrescine (1c,s et to 100 %), and thereafter,t he activity subsequently decreasedi nastepwise mannerw ith increasing chain length from 1d to 1f.D iamines containing greater than eight C atoms, that is, 1g-i,h ad correspondingly lower measureable activity.W ea lso examined diamines 2a-c, 3a,a nd 3b containing heteroatoms in addition to branched diamine 4.A ll of these diamines were shown to be active, although the lower activities of the bulky substrates can possibly be rationalized by the presence of as mall substrate binding-site entrance with ah ighlyh ydrophobic channel to the active-site cavity relative to that of other class III transaminases. [22] Interestingly,p utrescine transaminase was found to exhibit highers electivity for diamines than for monoamines of comparable size;f or example, putrescine (1c)s howedh igha ctivity with Ec-ygjG pATA,w hereas correspondingm onoamine butyl amine 6 showed no detectible activity. Ornithine 5,m ono Ntert-butoxycarbonyl (Boc)-protected derivatives of 1a and 1b (amines 10 and 11,r espectively), and diamines 7a, 7b, 8,a nd 9 were also found to be inactives ubstrates, which suggests that the ygjG enzyme is strictly involved in the degradation of linear diamines (see Ta ble S2).…”