. The actinomycetes. Actinomycetales. CH, The polypeptide portions of the various actino- mycins contain a variety of amino acids differing in their identity, arrangement, and number. Physical and chemical variations observed be- tween various components appear to be caused by these differences. To date, all actinomycins de- scribed contain L-threonine and sarcosine (Table 39). The complete structures of actinomycins I to VII are shown below, and some of their properties are given in Table 40 (44, 57, 63, 65, 95, 101). —L-valine-N—CH3 N—CHrL-valine—, sarcosine sarcosine A B C D -L-threonine L-
. The actinomycetes. Actinomycetales. CH, The polypeptide portions of the various actino- mycins contain a variety of amino acids differing in their identity, arrangement, and number. Physical and chemical variations observed be- tween various components appear to be caused by these differences. To date, all actinomycins de- scribed contain L-threonine and sarcosine (Table 39). The complete structures of actinomycins I to VII are shown below, and some of their properties are given in Table 40 (44, 57, 63, 65, 95, 101). —L-valine-N—CH3 N—CHrL-valine—, sarcosine sarcosine A B C D -L-threonine L-threonine- CO. CH3 ^ CH, Basic structure of actinomycins Variations from one actinonivcin to the other occur at the locations marked .4, B, ('. and D as follows: Actinomycin I: .1 = L-proline, B = hydroxy- proline, C = D = D-valine (44). Actinomycin II: A = B = sarcosine, C = D = D valine (101). Actinomycin III: .I = proline, B = sarcosine, (' = JJ = D-valine (101). Actinomycin IV: ,1 = B = L-proline, (' — D = D- valine (65). Actinomycin V: .1 = proline,/? = 4-ketoproline, (• = JJ = D-valine (95). Actinomycin VI: C = D-valine, D = D-alloiso- leucine,.! = B = L-proline (57). Actinomycin VII: r = D = D-alloisoleucine, A = /i = L-proline (57). Actinomycins which have been characterized biologically are active on gram-positive bacteria, less active on mycobacteria, and inactive on fungi and gram-negative bacteria, although their activ- ity varies quantitatively. One report of antiviral activity exists (80). Many are active on tumors in animals, and certain actinomycins have been re- ported to have a temporary activity on neoplasms in man (21, 27, 41-43, 49, 76). All are very toxic substances. Many cause splenic atrophy in animals after multiple doses (CO). Actinomycin-producers thus far reported are all members of the family Streptomycetaceae. Some actinomycin-producing cultures have been found under various conditions to form the compo- nents of their "mixtures&qu
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