C-19393 E5, a new carbapenem antibiotic. Fermentation, isolation and structure

A new carbapenem antibiotic, C-19393 E5, was isolated from the culture filtrate of Streptomyces griseus subsp. cryophilus C-19393 as a minor component. The chemical structure of the antibiotic was determined by comparing its spectral data with those of the known 5,6-cis carbapenem antibiotics and confirmed by partial synthesis from epithienamycin B as shown in Fig. 1. The antibiotic has a broad antimicrobial spectrum and shows strong inhibitory activity against beta-lactamases.

Proton and hydroxide ion permeability of phospholipid vesicles

The apparent permeability of H+ through phospholipid bilayers was determined by measuring H+ efflux from large unilamellar phospholipid vesicles with internal space buffered at pH 4. The value obtained is about 10(-9) cm/sec at room temperature, five orders of magnitude lower than was recently reported for the combined permeability for H+ and OH- [Nichols, J. W. & Deamer, D. W. (1980) Proc. Natl. Acad. Sci. USA, 77, 2038-2042]. The apparent permeability measured in this way is the sum of contributions from the movement of H+ and of uncharged species (HCl or HNO3) in equilibrium with anions in the solution. There is evidence that the uncharged species make the dominant contribution and that the permeability coefficient for H+ per se is no larger than 5 X 10(-12) cm/sec. An attempt to measure OH- permeability by use of vesicles buffered at pH 10 did not give a conclusive result because the vesicle walls appeared to be damaged by exposure to this pH. An apparent permeability coefficient of about 10(-7) cm/sec was estimated for undamaged membranes.

No reduction of blood glucose in diabetic rats after oral administration of insulin liposomes prepared under acidic conditions

Insulin liposomes (dipalmitoyl phosphatidylcholine or dimyristoyl phosphatidylcholine/cholesterol = 7/2) were prepared under strongly acidic conditions maintaining the biological activity of insulin. Although these were apparently noncharged liposomes, the association of insulin with membrane of liposomes was unexpectedly very large, and the uptake % of insulin was high. The distribution of vesicle-size of liposomes was narrow; the average diameter was 9.1 micrometer and no multilayered structures were observed by electron microscopy. Oral administration of the insulin liposomes (15-30 IU/rat) in streptozotocin-diabetic rats did not result in any distinct tendency to reduce the level of blood glucose.

Phospholipid vesicle formation and transmembrane protein incorporation using octyl glucoside

Removal of detergent from mixed micelles of egg yolk phosphatidylcholine and octyl glucoside leads to formation of unilamellar phospholipid vesicles with a diameter of about 230 nm. The same procedure applied to mixed micelles containing the transmembrane protein glycophorin A, in addition to lipid and detergent, produces vesicles of the same size with glycophorin incorporated into the bilayer. The pure lipid vesicles are highly impermeable to both anions and cations, and incorporation of up to 220 molecules of glycophorin per vesicle has little effect on permeability.

C-19393 S2 and H2, new carbapenem antibiotics. III. Mode of action

Biochemical activities of new carbapenem antibiotics, C-19393 H2(H2) and C-19393 S2(S2), were examined in comparison with those of mecillinam using Escherichia coli. H2 showed remarkably high affinity for penicillin-binding protein (PBP) 2, and high affinity for PBPs 1 and 3. S2 showed high affinity for PBP 2, moderate affinity for PBP 1 and low affinity for PBP 3. They induced ovoid cells at lower concentrations and cell lysis at higher concentrations. The inhibitory potency of H2 for peptidoglycan synthesis was similar to that of mecillinam at lower concentrations up to 0.1 micrograms/ml. At concentrations higher than 0.1 micrograms/ml, the inhibition rate by H2 gradually increased up to 100%, whereas that by mecillinam remained at 60% level. The MICs of H2, S2 and mecillinam corresponded to the lowest concentrations giving 60% of inhibition of peptidoglycan synthesis at which concentrations the function of PBP 2 seemed to be prevented completely. These findings indicate that the primary targets of H2 and S2 are PBP 2 involved in cell shape determination in E. coli.

C-19393 S2 and H2, new carbapenem antibiotics. IV. Inhibitory activity against beta-lactamases

New carbapenem antibiotics, C-19393 S2 and H2, have been found to be potent and broad-spectrum inhibitors of beta-lactamases. Among 11 types of beta-lactamases tested, those from Escherichia coli (plasmid-bearing), Klebsiella pneumoniae, Proteus vulgaris, Serratia marcescens and Bacteroides fragilis were especially sensitive. They also inhibited cephalosporinases insensitive to clavulanic acid. The inhibition by C-19393 S2 and H2 was of progressive type, except for the inhibition of E. coli enzyme (plasmid-mediated type I) by C-19393 H2. The inhibition of E. coli beta-lactamase by C-19393 S2 was irreversible, while that by C-19393 H2 was reversible.

Cefmenoxime (SCE-1365), a novel broad-spectrum cephalosporin: in vitro and in vivo antibacterial activities

The activity of cefmenoxime (SCE-1365), 7 beta-[2-(2-aminothiazol-4-yl)-(Z)-2-methoxyiminoacetamido]-3-[(1-methyl-1H-tetrazol-5-yl)thiomethyl]ceph-3-em-4-carboxylic acid, was compared with that of other cephalosporins. Cefmenoxime exhibited high activity against a wide variety of gram-positive and gram-negative bacteria. The in vitro activity of cefmenoxime against Streptococcus pyogenes, Haemophilus influenzae, and Enterobacteriaceae, including indole-positive Proteus, Serratia marcescens, Enterobacter cloacae, and Citrobacter freundii, was 10 to 1,000 times greater than that of several other cephalosporins. Against Pseudomonas aeruginosa, cefmenoxime showed activity two to four times that of sulbenicillin and carbenicillin but less than that of cefsulodin. Variation in pH, addition of horse serum, and type of growth medium had definite effects on the activity of cefmenoxime, and the inoculum size affected the activity against bacterial species. In Escherichia coli cefmenoxime showed marked affinity for penicillin-binding protein 3 (PBP-3), followed by PBP-1 (1A and 1B). This affinity profile was well correlated with its filamentous cell-forming activity under extremely low drug concentrations and with its bactericidal activity against microorganisms. The high in vitro activity of cefmenoxime was reflected in the degree of protection observed in mice infected intraperitoneally with a wide variety of gram-positive and gram-negative bacteria. Furthermore, cefmenoxime showed good therapeutic activity against infection models in mice such as respiratory tract infection caused by Klebsiella pneumoniae and urinary tract infection caused by Proteus mirabilis.

C-19393 S2 and H2, new carbapenem antibiotics. II. isolation and structures

Two new beta-lactam antibiotics, C-19393 S2 (1) and H2 (2), were isolated from the culture filtrate of Streptomyces griseus subsp. cryophilus nov. subsp. The structures were determined by spectral analysis as shown in Fig. 2. The antibiotics have broad antimicrobial activity and strongly inhibit beta-lactamases. The minor product (2) is more stable than cephalosporin C in aqueous solution.

C-19393 S2 and H2, new carbapenem antibiotics. I. Taxonomy of the producing strain, fermentation and antibacterial properties

C-19393 S2 and H2 are new carbapenem antibiotics produced by a streptomycete. The producing strain was taxonomically studied and named Streptomyces griseus subsp. cryophilus. Cobaltous compounds were necessary for production of the antibiotics. C-19393 S2 and H2 showed a broad spectrum of antibacterial activities with C-19393 H2 being 8 approximately 120 times more active than C-19393 S2. They also exhibited beta-lactamase-inhibiting activities and acted synergistically with ampicillin and cefotiam against clinical isolates resistant to beta-lactam antibiotics.

SCE-963, a new potent cephalosporin with high affinity for penicillin-binding proteins 1 and 3 of Escherichia coli

A few biochemical activities of SCE-963, a new cephalosporin with potent antibacterial activities against gram-negative bacteria, were compared with those of several currently available cephalosporins against strains of Escherichia coli K-12. The minimum inhibitory concentrations of SCE-963, cefazolin, cephaloridine, cephalothin, and cephalexin were 0.2, 1.56, 3.13, 12.5, and 25 mug/ml, respectively. Affinities of these cephalosporins for the penicillin-binding protein (PBP) 1B of E. coli correlated well with their antibacterial activities; among tested cephalosporins, SCE-963 showed the highest affinity for PBP 1B. SCE-963 inhibited cross-linking of peptidoglycan in a cell-free system the most strongly suggesting that this inhibition results from its high affinity for PBP 1B. SCE-963 also showed the highest affinity for PBP 3; it caused filamentation of cells over a wide range of relatively lower concentrations. Thus its superior antibacterial activity is believed to be manifested through its high affinity for the PBPs.

Association of the major coat protein of fd bacteriophage with phospholipid vesicles

The association of the major coat protein of fd bacteriophage with a phospholipid bilayer was investigated by analyzing the protein's susceptibility to proteolysis and its circular dichroism spectrum when incorporated into single-walled phospholipid vesicles. In the limits tested, this association appeared to be independent of the mass ratio of protein to lipid and of vesicle size, phospholipid composition, and method of preparation. The circular dichroism data are consistent with a similar "membrane-bound" conformation for all cases of vesicle-associated coat protein and for deoxycholate micelle-associated coat protein. Proteolysis of coat protein associated with deoxycholate micelles and with phospholipid vesicles defined the central hydrophobic core presumed to represent that portion of the protein which associates with membrane bilayers in vivo. The isolated core, which assumed a predominantly beta-type conformation in detergent solution, maintained a beta conformation when associated with a vesicle phospholipid bilayer.

Conformational states of a hydrophobic protein. The coat protein of fd bacteriophage

The coat protein of fd bacteriophage has a short polypeptide chain of only 50 amino acid residues, containing a highly hydrophobic segment of 19 amino acids that is entirely devoid of ionic or other strongly polar amino acids. In the viral particle the protein exists as a closely packed array of alpha helices. It can be transformed to a monomeric randomly coiled polypeptide in very concentrated (greater than or equal to 7.3 M) guanidinium chloride. In anionic detergents or phospholipids the protein is dimeric, with a mixed conformation ("50% alpha"), the hydrophobic segment having a beta structure, whereas the two ends are predominantly alpha helical. In guanidinium chloride at concentrations of 6 M or less, and under other conditions in the absence of an anionic detergent or phospholipid, the protein forms an intractable polymer, with a beta-type conformation. If the protein is succinylated an oligomeric form of this structure (speculatively thought to be a soluble variety of a "beta barrel") can be obtained as a metastable state. The 50% alpha conformation, the beta oligomer, and the random coil can be interconverted reversibly, but formation of the beta polymer appears to be irreversible.

Carriomycin, a new polyether antibiotic produced by Streptomyces hygroscopicus

Carriomycin, a new polyether antibiotic, was isolated from culture broth of Streptomyces hygroscopicus strain T-42082. It is active against Gram-positive bacteria, several fungi, yeasts and mycoplasma. It is also coccidiostatic. The free acid of carriomycin occurs as colorless prisms having the molecular formula C47H80O15 (M.W. 885.15), m.p. 120 approximately 122 degrees C and [alpha]25D -0.5 in methanol. It has no characteristic absorption maxima in the ultraviolet spectrum. The presence of one carboxyl and three methoxy groups was observed from its infrared, PMR and CMR spectra.

Regulation of glucosamine utilization in Staphylococcus aureus and Escherichia coli

Glucosamine- or N-acetylglucosamine-requiring mutants of Staphylococcus aureus 209P and Escherichia coli K12, which lack glucosamine-6-phosphate synthetase [2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase (amino-transferring); EC 5.3.1.19], were isolated. Growth of these mutants on glucosamine was inhibited by glucose, but growth on N-acetylglucosamine was not. Addition of glucose to mutant cultures growing exponentially on glucosamine inhibited growth and caused death of bacteria, though chloramphenicol prevented death. Uptake of glucosamine by S. aureus and E. coli mutants was severely inhibited by glucose whereas uptake of N-acetylglucosamine was only slightly inhibited. Uptake of glucose was not inhibited by either glucosamine or N-acetylglucosamine. In glucosamine auxotrophs, glucose causes glucosamine deficiency which interrupts cell wall synthesis and results in some loss of viability in the presence of continued protein synthesis.

Use of gel chromatography for the determination of the Stokes radii of proteins in the presence and absence of detergents. A reexamination

In the course of a routine investigation of the complex between the erythrocyte membrane protein spectrin and sodium dodecyl sulfate, we observed a large discrepancy between the true Stokes radius (178 A, measured by hydrodynamic methods) and the apparent value derived from gel chromatography (107 A). In attempting to resolve this discrepancy, we have experiments that indicate that all large asymmetric particles may be subject to a similar discrepancy; e.g., native fibrinogne has a true Strokes radius of 108 A, whereas the value derived by column chromatography after calibration with globular proteins is only 71 A. The simplest interpretation is that end-on insertion of asymmetric particles into the gel pores contributes to their retardation. The phenomenon clearly limits the usefulness of gel chromatography as a quantitative measure of the hydrodynamic Stokes radius. Incidental data obtained in the course of this work indicate that spherical viruses may have weak chemical affinity for the porous gel. Chromatography of large proteins in the presence of detergents produced no effects ascribable to absorption of the detergents, but the results suggest a need for further study of possible interaction between detergents and small gel pores.