Specific inhibition of aspartase by S-2,3-dicarboxyaziridine

Aspartase of Escherichia coli was inhibited in a competitive manner by S-2,3-dicarboxyazirdine (DCAZ), an antibacterial substance against Aeromonas salmonesida. The inhibition constant (Ki) was 55 microM, which was as low as less than one tenth that of the Km value for the substrate, L-aspartate. In view of the fact that both aspartase and fumarase (J. Greenhut et al. (1985) J. Biol. Chem. 260, 6684-6686) were inhibited by DCAZ in competitive manners, common features of the reaction mechanism of the two enzymes were discussed.

Protease-inhibitory activities of leupeptin analogues

Thirty analogues of leupeptin were synthesized and examined for their inhibitory activities against trypsin, papain, plasmin, kallikrein, thrombin and urokinase in vitro. Benzoyl- and alpha-naphthalenesulfonyl-L-leucyl-L-argininal were 8 times more inhibitory to papain, benzyloxycarbonyl-L-pyroglutamyl-L-leucyl-L-argininal 10 times more to trypsin and plasmin, and DL-2-pipecolyl-L-leucyl-L-argininal 25 times more to kallikrein than leupeptin. Against urokinase, only L-pyroglutamyl-L-leucyl-L-argininal exhibited a potent inhibitory activity. alpha-Naphthalensulfonyl-, dansyl- and benzyloxycarbonyl-(2S,3R)-3-amino-2-hydroxy-4-phenylbutyryl-L-leucyl-L- argininal were inhibitory to thrombin.

The antiproliferative action of deoxyspergualin is different from that induced by amine oxidase

The amine oxidase activities contained in calf serum and human serum were detected at levels of 90.8 and less than 0.1 nmol O2/minute/ml serum, respectively, by measuring oxygen consumption coupled with spermidine oxidation. Deoxyspergualin (NKT-01) and spergualin (SGL) containing spermidine in their structure were also oxidized in calf serum at the rate of 3.6 and 11.6 nmol O2/minute/ml serum, respectively. To investigate whether amine oxidase is essential for NKT-01 and SGL to exhibit their antiproliferative activities or not, the in vitro activities of NKT-01, SGL and polyamines against L1210 cells were examined in the presence of calf or human serum. Polyamines exhibited antiproliferative activity only in the presence of calf serum, while NKT-01 and SGL inhibited cell growth in the presence of both calf and human serum. In the presence of calf serum the activity of NKT-01 was inhibited by aminoguanidine, an amine oxidase inhibitor. Aminoguanidine did not inhibit the activity of NKT-01 in the presence of human serum. The activity of NKT-01 was shown at much lower concentrations in the presence of human serum than that in the presence of calf serum, and was strongly dependent on incubation time. The in vivo activities of NKT-01, SGL and SGL derivatives correlated with their in vitro activities in the presence of human serum. These results suggest that the in vivo antitumor activities of NKT-01, SGL and SGL derivatives may be attributed to a mechanism different from those of amine oxidase-oxidized product and represent a novel growth inhibitory action.

Determination of deoxyspergualin by gas chromatography-selected-ion monitoring

A gas chromatographic-selected-ion monitoring method was developed for the sensitive and specific determination of deoxyspergualin in dog plasma using a capillary column and a C8-amide homologue of deoxyspergualin as an internal standard. Extraction and purification of deoxyspergualin from its constituents, 7-guanidinoheptanamide and glyoxylylspermidine, and its possible metabolites was achieved by using CM-Sephadex C-25 column chromatography with stepwise elution with sodium chloride solution. Treatment of deoxyspergualin with acetylacetone resulted in the formation of the volatile pyrimidine derivative of 7-guanidinoheptanamide accompanying hydrolytic cleavage in the alpha-hydroxyglycine moiety of deoxyspergualin. Deoxyspergualin could be determined in a concentration of 10 ng/ml in plasma. The method was applied to the determination of deoxyspergualin in plasma during and after intravenous infusion into dogs.

Bisucaberin, a new siderophore, sensitizing tumor cells to macrophage-mediated cytolysis. II. Physico-chemical properties and structure determination

The structure of bisucaberin, a new siderophore, was determined to be 1,12-dihydroxy-1,6,12,17-tetraazacyclodocosane-2,5,13,16-tetron e by spectroscopic analysis and X-ray crystallographic analysis. The molecule of bisucaberin consists of a cyclic dimer of 1-hydroxy-1,6-diazaundecane-2,5-dione moiety and is closely related to nocardamine, the trimer of the same moiety.

Biosynthesis of napyradiomycins

Biosynthetic studies on napyradiomycins were carried out based on the incorporation of [2-13C]acetate and [1,2-13C]acetate. The alignment of acetate units suggested that the B and C rings of napyradiomycins are derived from a pentaketide, while ring A and the side chain may be synthesized from mevalonate.

Bisucaberin, a new siderophore, sensitizing tumor cells to macrophage-mediated cytolysis. I. Taxonomy of the producing organism, isolation and biological properties

Alteromonas haloplanktis strain SB-1123 isolated from deep-sea mud produced a new siderophore, bisucaberin. Bisucaberin rendered tumor cells susceptible to cytolysis mediated by murine peritoneal macrophages which were elicited by Proteose peptone and not yet activated by lymphokine. Bisucaberin exerted its sensitizing activity by both the preincubation with tumor cells and the addition to co-culture of macrophages and tumor cells. The activity of bisucaberin was specifically inhibited by ferric ion. Bisucaberin showed direct cytostasis for tumor cells but did not cause cytolysis in the absence of macrophages. Cytostasis by bisucaberin was attributable to the specific inhibition of DNA synthesis in tumor cells.

Monocyclic beta-lactam antibiotics: synthesis and antibacterial activity of 4-(substituted ethyl)-2-azetidinone-1-sulfonic acid derivatives

The synthesis and antibacterial activity of sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-(O-substituted oxyimino)acetamido]-2-azetidinone-1-sulfonates having various substituted ethyl groups at the C-4 position are described. Among various substituents explored, the (substituted isothiuronio)ethyl groups were found to have strong antibacterial activity against a variety of Gram-negative bacteria, and moreover, the ethylene isothiuronium derivative exhibited moderate antibacterial activity against Staphylococcus aureus.

Synthesis of antitumor-active 7-O-(2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl)-daunomycinone and -adriamycinone

The title compounds (17 and 23) were prepared by coupling 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-alpha-L-talopyranosyl bromide (15) with daunomycinone. The key step in the preparation of 15 was the epoxide-ring opening of methyl 2,3-anhydro-4-O-benzyl-6-deoxy-alpha-L-gulopyranoside with KHF2 in ethylene glycol, whereupon 2-fluoro-alpha-L-idopyranoside was obtained. Compounds 17 and 23 showed strong antitumor activity.

Immunosuppressive activity of 15-deoxyspergualin and its effect on skin allografts in rats

The immunosuppressive activity of spergualin analogues, 15-deoxyspergualin and N-30, is presented. These compounds suppressed antibody formation and establishment of delayed-type hypersensitivity to sheep red blood cells (SRBC) in mice. Among spergualin, 15-deoxyspergualin, and N-30, 15-deoxyspergualin was most effective in suppressing immune responses. It suppressed antibody formation against SRBC by spleen cell cultures in a dose-dependent fashion without reducing cell viability. The spergualins also suppressed the mixed lymphocyte culture reaction. Peritoneal exudate cells taken from mice given immunosuppressive doses of 15-deoxyspergualin were not reduced in their functions measured: Release of lysosomal enzymes and production of superoxide anions. 15-Deoxyspergualin and N-30 were markedly effective in prolonging skin graft in rats.

In situ inhibition of tyrosine protein kinase by erbstatin

Erbstatin inhibited the kinase activity of the receptor for epidermal growth factor in cultured A431 cells, while it did not alter turnover of the receptor protein. It also inhibited autophosphorylation of the src gene product p60src in Rous sarcoma virus-infected normal rat kidney cells. Erbstatin did not inhibit the binding of epidermal growth factor to its receptor but did inhibit internalization of epidermal growth factor-receptor complexes. It did not inhibit the epidermal growth factor-stimulated phosphatidylinositol turnover in A431 cells. Thus, erbstatin inhibited two oncogene product-related tyrosine protein kinases in situ and thus is a useful tool to study the role of tyrosine protein kinase.

Action of ubenimex on aminopeptidase activities in spleen cells and peritoneal macrophages from mice

The action of ubenimex on aminopeptidase (APase) activity was studied in intact spleen cells and peritoneal macrophages from mice. Ubenimex strongly inhibited hydrolyzing activities against arginine-beta-naphtylamide (Arg-NA), Lys-NA and Pro-NA in both cells. Inhibition of hydrolysis of Leu-NA, Met-NA and Ala-NA was relatively small or not observed. When both cells were incubated in HANKS' solution, hydrolyzing activities against Arg-NA, Lys-NA and Pro-NA were released to the medium, while Leu-NA and Met-NA-hydrolyzing activities were mostly bound. In addition, the Leu-NA-hydrolyzing activity in the spleen cells was kinetically studied. The Arg-NA and Leu-NA-hydrolyzing activities in four fractions prepared from the homogenate of spleen cells were also studied kinetically. From these studies it was suggested that ubenimex inhibits aminopeptidase B and a Pro-NA-hydrolyzing enzyme more effectively than Leu-APase in intact spleen cells and peritoneal macrophages from mice.

Sulfhydryl modification and activation of phenylalanine hydroxylase by dinitrophenyl alkyl disulfide

A new family of asymmetric thiol-disulfide exchange reagents, the dinitrophenyl alkyl disulfides (DNPSSR), was used to modify rat liver phenylalanine hydroxylase. The results indicate that the enzyme has two different types of reactive sulfhydryl (SH) residues per subunit. One SH residue was modified selectively by a DNPSSR having a neutral and hydrophilic alkyl group, and this modification was accompanied by appreciable activation of enzyme; the other SH residue was modified only by an anionic DNPSSR, and this modification did not result in activation. The catalytic properties of phenylalanine hydroxylase activated by DNPSSR were similar to those of the N-ethylmaleimide- (NEM-) modified enzyme, but the process of activation by DNPSSR was quite different from modification with NEM. An analysis of the reaction kinetics of the modification and of catalysis by the modified enzyme suggests that DNPSSR modification causes a change in the subunit interaction leading to a loss of the negative cooperativity normally seen with phenylalanine hydroxylase.

Decreased activities of serine proteinases in spleen of various murine models of systemic lupus erythematodes

Previous studies indicated a relationship between immune deficiencies and abnormalities in the activities of various hydrolytic enzymes, including proteinases, in tissues. In the present study, we compared such activities in spleen among the three types of murine models of systemic lupus erythematodes (SLE) (i.e., New Zealand black/white mouse, MRL mouse, and BXSB mouse) and their controls. According to the results of multivariate analysis, it was shown that the most important enzymatic changes differentiating the pathologic animals from their controls were decreases in the activities of serine proteinases. Judging from the behavior of these enzymes in various immunological disturbances, it is likely that they play some important roles in pathophysiology of SLE.

Effect of spergualin in autoimmune disease mice

We investigated the effect of spergualin (SGL) upon the development of spontaneous systemic lupus erythematosus-like lesions in male MRL/MpJ-lpr/lpr mice. SGL was administered ip at doses of 2.5, 5 and 10 mg/kg to two groups of mice. One group received SGL prophylactically from 7 to 21 weeks of age. The other group received SGL curatively from 13 to 27 weeks of age. The occurrence of lupus lesions was characterized by enlarged lymphoid organs, high anti-DNA titer and blood urea nitrogen, and severe glomerular nephritis. In both groups these characteristics were significantly suppressed by SGL in a dose-dependent manner. This inhibitory activity was greatest at a dose of 10 mg/kg. These findings suggest that SGL has prophylactic and curative effects against lupus lesions in autoimmune disease in mice.

Immunosuppressive activities of deoxyspergualin. I. Effect of the long-term administration of the drug on the development of murine lupus

The effect of 15-deoxyspergualin, a newly developed anti-tumor agent, on the development of spontaneously occurring lupus glomerulonephritis in male BXSB and MRL/lpr mice was examined. The prophylactic effect of 15-deoxyspergualin was evaluated using 8-week-old male BXSB mice. Its therapeutic effect was estimated using male BXSB and MRL/lpr mice of 13 weeks of age. Treatment with 15-deoxyspergualin at a dose of 5 mg/kg for 5 weeks suppressed the increment of IgG-producing cells in the spleen, decreased serum levels of circulating immune complexes assessed by solid-phase C1q-binding assay and effectively prevented the deposition of immune complexes in renal glomeruli estimated by immunofluorescent studies in both strains of mice. 15-Deoxyspergualin was also effective in preventing the massive lymphoproliferation characteristic of MRL/lpr mice as assessed by the weight of mesenteric lymph nodes. It seemed quite valuable that 15-deoxyspergualin drastically suppressed the progress of polyclonal B cell activation in both strains of autoimmune mice, which have different mechanisms leading to B cell activation. These results suggest that 15-deoxyspergualin might be used as a therapeutic agent for human erythematosus.

Immunosuppressive activities of deoxyspergualin. II. The effect on the antibody responses

We examined the suppressive effect of a newly developed antitumor agent, 15-deoxyspergualin (DSP), on the plaque-forming cell responses to various antigens. The intraperitoneal injections of DSP at a dose of 5.0 mg/kg body weight suppressed drastically the development of plaque-forming cells in the spleen of C57BL/6 mice immunized with sheep red blood cells (0.2 ml of a 5% suspension), trinitrophenyl-lipopolysaccharide (1 microgram/mice) and trinitrophenyl-Ficoll (100 micrograms/mice). These suppressive effects were observed when the administration of DSP was started after the injection of antigens. The responsiveness of spleen cells from DSP-treated mice was also checked in in vitro culture. Responsiveness to lipopolysaccharide in vitro was not reduced. Furthermore DSP did not significantly suppress the responsiveness of spleen cells to succinylated concanavalin A or production of interleukin-1 or -2. The results are discussed with regards to the mode of action of DSP on immune responsiveness.

A multivariate study on enzymatic changes in limb muscles and heart muscle of dystrophic mice

The present study was undertaken to elucidate further the enzymatic changes in dystrophic muscle using multivariate analysis. The activities of 14 kinds of enzymes, including 6 exopeptidases, 4 endopeptidases, beta-N-acetyl-D-glucosaminidase, phosphatase, esterase, and ribonuclease, were examined in forelimb and hindlimb muscles as well as in cardiac muscle of dystrophic mice and their controls. Two principal components identified from the enzymatic spectrum proved to be related especially to aminopeptidases and to serine proteinases, respectively. The enzymatic changes in forelimb muscle were very similar to those in hindlimb muscle when both were compared to those in cardiac muscle. The changes in aminopeptidases were unique to the limb muscles, whereas those of serine proteinases were unique to cardiac muscle of dystrophic mice. In the future, more attention should be focused on the role of exopeptidases in pathogenetic mechanisms of muscular dystrophy, because of the possibility that they play a major role in the initial stage of muscular dystrophy.