5. ANTIBIOSIS AND ANTIBIOTICS
293
metabolic product from Bacillus mesentericus. This type of oxygen
bridge occurs in a number of cyclic antibiotic peptides containing, in
addition to amino acids, α-hydroxyisovaleric acid (HIV), first discovered
in sporidesmolide I (LXIV), a metabolic product from Phytomyces
chartarum (Sporidesmium bakeri) (196a,b). Examples of those compounds, for which the names peptolides and depsipeptides were suggested, are amidomycin (LXV) from Streptomyces sp. and several antibiotics produced by species of the genera Fusarium and Gibberetta: the
enniatins A (LXVI) (196c), Β (LXVII) (196d), and C (LXVIII) and
the lateritiins (lateritiin II, avenacein, fructigenin, sambucinin).
In valinomycin (LXIX) or aminomycin from S. fulvissimus and other
streptomycetes (196e,f), lactic acid (Lac) is present together with Hiv.
In the antimycins (197) or antipiriculins, produced by several species of
streptomycetes (S. griseus, S. kitasawaensis, S. blastmyceticus),
the
amino acid moiety becomes only a minor part of the whole structure
(LXX). Antimycins are specific respiration inhibitors. They block electron transfer, some of them by preventing the oxidation by cytochrome c
of reduced cytochrome b (198, 199a^d).
5. Proteinaceous Antibiotics
The colicins (67), and possibly other bacteriocins (200a,b) such as
megacins (200c, 201a,b), pyocins (202a,b), pesticins (203, 204), vibriocins (205), are complex antibiotics generally considered to be proteins or
at least to contain an important proteinaceous moiety. In fact, their chemistry has been investigated in but a few cases. Colicins Κ and V are
considered as lipocarbohydrate-protein complexes identical with somatic
Ο antigens (206, 207a,b), but megacin (208) appears to be a pure protein. Their biochemical mode of action is unknown, although, in the
case of megacin, leakage of cell components following damage to the
cytoplasmic membrane was reported (209a). Colicins, like the bacteriophage capsides, to which they have been likened, attach themselves to
specific cell receptors and, once thus bound, inhibit further synthesis of
nucleic acid (209b).
Several protein enzymes which are able to kill microorganisms, or
even to dissolve (210, 211) living bacterial bodies, are undoubtedly to be
included, on that account, among the antibiotics. The best known of them
is lysozyme (212, 213), which not only is found in the tissues and secretions of various animal species, particularly in egg white, but is also
produced by bacteria, for instance, Bacillus subtilis and Staphylococcus
aureus (126, 214). This enzyme digests a universal component (69a) of
the bacterial cell wall (215a,b), responsible for its mechanical strength,
with the result that the wall-less protoplast or wall-deficient spheroplast
293
metabolic product from Bacillus mesentericus. This type of oxygen
bridge occurs in a number of cyclic antibiotic peptides containing, in
addition to amino acids, α-hydroxyisovaleric acid (HIV), first discovered
in sporidesmolide I (LXIV), a metabolic product from Phytomyces
chartarum (Sporidesmium bakeri) (196a,b). Examples of those compounds, for which the names peptolides and depsipeptides were suggested, are amidomycin (LXV) from Streptomyces sp. and several antibiotics produced by species of the genera Fusarium and Gibberetta: the
enniatins A (LXVI) (196c), Β (LXVII) (196d), and C (LXVIII) and
the lateritiins (lateritiin II, avenacein, fructigenin, sambucinin).
In valinomycin (LXIX) or aminomycin from S. fulvissimus and other
streptomycetes (196e,f), lactic acid (Lac) is present together with Hiv.
In the antimycins (197) or antipiriculins, produced by several species of
streptomycetes (S. griseus, S. kitasawaensis, S. blastmyceticus),
the
amino acid moiety becomes only a minor part of the whole structure
(LXX). Antimycins are specific respiration inhibitors. They block electron transfer, some of them by preventing the oxidation by cytochrome c
of reduced cytochrome b (198, 199a^d).
5. Proteinaceous Antibiotics
The colicins (67), and possibly other bacteriocins (200a,b) such as
megacins (200c, 201a,b), pyocins (202a,b), pesticins (203, 204), vibriocins (205), are complex antibiotics generally considered to be proteins or
at least to contain an important proteinaceous moiety. In fact, their chemistry has been investigated in but a few cases. Colicins Κ and V are
considered as lipocarbohydrate-protein complexes identical with somatic
Ο antigens (206, 207a,b), but megacin (208) appears to be a pure protein. Their biochemical mode of action is unknown, although, in the
case of megacin, leakage of cell components following damage to the
cytoplasmic membrane was reported (209a). Colicins, like the bacteriophage capsides, to which they have been likened, attach themselves to
specific cell receptors and, once thus bound, inhibit further synthesis of
nucleic acid (209b).
Several protein enzymes which are able to kill microorganisms, or
even to dissolve (210, 211) living bacterial bodies, are undoubtedly to be
included, on that account, among the antibiotics. The best known of them
is lysozyme (212, 213), which not only is found in the tissues and secretions of various animal species, particularly in egg white, but is also
produced by bacteria, for instance, Bacillus subtilis and Staphylococcus
aureus (126, 214). This enzyme digests a universal component (69a) of
the bacterial cell wall (215a,b), responsible for its mechanical strength,
with the result that the wall-less protoplast or wall-deficient spheroplast