The proteinous antibiotic neocarzinostatin was succinylated using succinic anhydride, and two bis-succinyl compounds, neocarzinostatin derivatives (SUC-I and SUC-II), were obtained. The biological and chemical properties of SUC-I and SUC-II were investigated after separation by column chromatography. The only free amino groups in neocarzi-nostatin were succinylated completely in both derivatives. Amino terminal analysis, electrophoretic mobility and amino acid analysis were the same for both derivatives. However, only SUC-II was biologically active when assayed on three human cell lines and Sarcina lutea. Analysis by UV spectroscopy and circular dichroism indicated a difference in the molecular conformation, perhaps a slightly losened structure in SUC-I as compared with SUC-II. These isologous derivatives with different biological and optical activity have also been observed in neocarzinostatin. SUC-I seems to be a counterpart of "pre-NCS", an inactive form of NCS. SUC-II differs from NCS in being completely devoid of cytolytic and cytocidal activity. The retention of biological activity in bis-N-succinyl neocarzinostatin, in which all amino groups are bolocked, indicates that in NCS free amino groups are not essential for activity.

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Base-catalyzed addition of thioglycolic acid to the dehydrobutyrine residue in stendomycinfollowed by hydrolysis and isolation of the newly formed amino acid (S-carboxy-methyl-β-methylcysteine) provided a pair of optically active diastereoisomers. Thus, the addition of the thiol to the double bond is stereoselective and is governed by thearchitecture of the molecule of the antibiotic.

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Kuwaitimycin influences the translocation of alkali metal cations in liver mitochondria.In presence of valinomycin, which stimulates uptake of potassium ions by the mitochondria, the addition of kuwaitimycin could augment the loss of these ions when the source of energy was mainly an oxidizable substrate. However, kuwaitimycin fail ed to cause loss of K⁺ from mitochondria in presence of appropriate amounts of ATP. A relation between the ionic size of the alkali metal cations and the inhibiting effect of the antibiotic on glutamate oxidation could be demonstrated. The ability of kuwaitimycin to restrain ATP supported oscillatory swelling associated with alkali metal cations transport induced by monazomycin was also demonstrated. The more voluminous the cation the more pronounced the effect on cation transport. The effect of kuwaitimycin on ATP hydrolysis in presence of different alkali metal cations
was found to be weak and independent or the cationic size.In light of the results obtained it is suggested that the antibiotic is exerting its effect on ion transport by inducing pores in the mitochondrial membrane and that the addition of appropriate amounts of ATP might alter the conformation of the mitochondrial membrane in such a way as to nullify the effect of the antibiotic.

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Zervamicins I and II are new polypeptide antibiotics produced by Emericellopsis salmosynnemata. Zervamicin I is an acidic compound while zervamicin II is a neutral polypeptide like emerimicins, antiamoebin and stilbellin to which both zervamicins are related.

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Aspiculamycin, a new cytosine nucleoside with versatile antibiotic activity, wasproduced by a strain of Streptomyces designated as S. toyocaensis var. aspiculamyceticus.The antibiotic was produced in submerged fermentation together with two otherantifungal antibiotics, toyocamycin and an unidentified tetraene antibiotic. Isolation ofaspiculamycin was proceeded by ion-exchange column chromatography of the culturefiltrate on IRC-50 followed by rechromatography on CG-50.

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Aspiculamycin (_I), C₁₉H₃₀N₈O₁₀, is a water-soluble basic antibiotic with versatile biological activities. From its physico-chemical properties, it has been characterized as one of the cytosine-nucleoside antibiotics for which the structure, 1-(4-sarcosyl-D-seryl-D-serylamino-4-deoxy-β-D-glucopyranosyluronamide) cytosine, is proposed.

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