Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0026936 (Mycoplasma)
14,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydrodynamic, chemical, and optical properties of arginine deiminase (EC 3.5.3.6) from Mycoplasma arthritidis are reported for the enzyme isolated from log phase cells. The S020,w and D020,w values of the enzyme are 5.48 S and 5.87 X 10(-7) cm3/s, respectively; the molecular weight is 87,300. Determination of the amino acid composition shows that about 45% of the residues are nonpolar. Another unique feature of the composition is the presence of 36 half-cystine residues. The state of oxidation of the half-cystines appears to be well established as 16 disulfide and 4 sulfhydryl groups. The reaction of 1 sulfhydryl group with 0.3 mM 5,5'-dithiobis(2-nitrobenzoic acid) has a half-life of about 50 min at pH 8. The modified enzyme retains full activity. Two -SH groups are accessible to this reagent in 2 M guanidine hydrochloride, whereas all 4 -SH groups react immediately in 4 M guanidine hydrochloride. Reduction of disulfide bonds with dithiothreitol occurs only to a limited extent in 8 M urea, but is complete in 4 M guanidine hydrochloride. The enzyme loses activity immediately at pH 2.5, but retains full activity upon standing 8 h at pH 9.5 in several buffers. The large number of cystine residues leads to a complex near ultraviolet circular dichroism spectrum with cystine contributions apparently superimposed on contributions from aromatic residues. The far ultraviolet spectrum suggests that the molecule contains about 18% alpha helix. At pH 2.5, beta conformation and disulfide contributions are dominant. Aromatic and alpha bands are reduced considerably at pH 9.5.
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PMID:Arginine deiminase from Mycoplasma arthritidis. Properties of the enzyme from log phase cultures. 68 35

The arginine deiminase (L-arginine iminohydrolase, EC 3.5.3.6) from Mycoplasma arthritidis catalyzes the irreversible hydrolysis of arginine and related guanidine derivatives to ammonia and the corresponding ureido analog of the substrate. The kinetic constants Km, kcat, and kcat/Km for the arginine deiminase-catalyzed hydrolysis of L-arginine are equal to 4 micron, 29 s-1, and 7.4 X 10(7) M-1 s-1, respectively, at 25 degrees C and pH 7.2. The enzyme also catalyzes the hydrolysis of L-canavanine, Nalpha-methyl-L-argine, D-arginine, L-homoarginine, L-argininic acid, and guanidine, in order of decreasing second order rate constants (kcat/Km); the second order rate constants for these substrates are 10(-3) to 10(-10) smaller than the rate constant for L-arginine. Twenty-two arginine and guanidine analogs were tested for inhibitory capacity. Only 13 are competitive inhibitors having Ki values in the range 3.2 to 40 mM. These results show that binding of ligands to the enzyme is dominated by electrostatic or hydrogen bonding interactions, or both, of the guanidino and alpha-amino group. Neither citrulline nor ornithine, the end product of arginine degradation in M. arthritidis, is an inhibitor of arginine deiminase from this organism.
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PMID:Arginine deiminase from Mycoplasma arthritidis. Structure-activity relationships among substrates and competitive inhibitors. 68 36

Arginine deiminase (EC 3.5.3.6) from Mycoplasma arthritidis ATCC 14152 has been purified 6-fold by a new procedure, protamine sulfate fractionation and DEAE-agarose chromatography. The yield was 75 to 85%. The homogeneity of the final preparation was demonstrated by gel filtration, sodium dodecyl sulfate-gel electrophoresis, NH2-terminal analysis, and polyacrylamide gel electrophoresis at two pH values. The enzyme has a molecular weight of 80,000 as measured by gel filtration. The dimeric nature of the enzyme is suggested by the molecular weight of 49,000 from sodium dodecyl sulfate-gel electrophoresis. Isoelectric focusing in polyacrylamide gels showed a major band corresponding to an isoelectric point of 7.0 and sometimes minor bands having lower isoelectric points. The ultraviolet spectrum exhibits a maximum at 278 nm. The enzyme has high affinity for L-arginine, with a Km value of 4 +/- 1 micronM at pH 7.2, 25 degrees. Mycoplasma arthritidis produces two distinct forms of arginine deiminase. Deiminase I is isolated from cells harvested during logarithmic phase; deiminase II is obtained from late logarithmic or early stationary phase cells. The two forms are resolved by DEAE-agarose chromatography and by polyacrylamide gel electrophoresis. Deiminase II elutes later from a DEAE-agarose column and moves toward the anode faster than deiminase I at pH 9.5 The two forms also have different specific activities and 280:260 spectral ratios. Each form has the same Km and molecular weight. A third form of the enzyme, deiminase III, can be generated by incubating deiminase II at pH 9.8, or in 50% saturated ammonium sulfate, pH 7.0, at 25 degrees. The transformation can be followed by chromatography and is completed within 10 h. The specific activity of deiminase III is 1.3 times that of deiminase II. No change in molecular weight or subunit dissociation was observed during the transformation. Deiminiase III has the same specific activity, absorbance ratio A280:A260, and electrophoretic properties as deiminase I. Deiminase I undergoes no change upon incubation at pH 9.8 for several days.
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PMID:Arginine deiminase from Mycoplasma arthritidis. Evidence for multiple forms. 85 96

Arginine has been considered as the major energy source of nonglycolytic arginine-utilizing mycoplasmata. When three strains of Mycoplasma arginini, and one strain each of Mycoplasma arthritidis, Mycoplasma fermentans, Mycoplasma gallinarum, Mycoplasma gallisepticum and Mycoplasma hominis were grown in the medium with high arginine concentration (34 mM) compared with low arginine (4 mM), both the protein content of the organisms and the specific activity of arginine deiminase increased. M. fermentans, the one arginine-utilizing species included in the survey which is also glycolytic, showed an increase in protein content but no increase in specific activity of the enzyme. The glycolytic non-arginine-utilizing M. gallisepticum did not show an increase in either parameter. The Km for arginine deiminase from crude cell extracts was 1.66 X 10(-4)M. The enzyme demonstrated a hyperbolic activation curve subject to substrate inhibition and was not affected by the presence of L-histidine. When mycoplasmic protein and arginine deiminase were determined for M. hominis under aerobic and anaerobic conditions, aerobically grown cells exhibited no detectable enzymatic increases until late in log phase. Higher levels of arginine deiminase were observed earlier in the anaerobic growth cycle. The rate of 14CO2 evolution from [guanido-14C]arginine was not altered in arginine-supplemented cells compared with cells grown in low arginine. In addition, CO2 production did not parallel increased arginine deiminase activity. These observations argue that arginine is used only as an alternate energy source in these organisms.
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PMID:Role of arginine deiminase in growth of Mycoplasma hominis. 126 6

The arginine deiminase gene of Mycoplasma hominis was amplified by the polymerase chain reaction, and its entire nucleotide sequence was determined. This gene consists of 1227 base pairs encoding 409 amino acids, and has 35.2% guanine plus cytosine content. Nucleotide sequence homologies of the arginine deiminase gene between M. hominis and M. arginini, and between M. hominis and M. orale were 82.1 and 80.8%, respectively, suggesting that this gene is highly conserved among arginine-utilizing Mycoplasma species.
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PMID:Nucleotide sequence of the arginine deiminase gene of Mycoplasma hominis. 152 17

Recently, we have demonstrated by molecular cloning that a strong immunosuppressive factor derived from Mycoplasma arginini is arginine deiminase. We show here that mycoplasma species identified in many of AIDS patients also bear the arginine deiminase gene. The implication of the arginine deiminase gene detected in AIDS-associated mycoplasma species is discussed.
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PMID:Arginine deiminase gene of an AIDS-associated mycoplasma, Mycoplasma incognitus. 152 18

Arginine deiminase (EC 3.5.3.6) was purified to homogeneity from the cell extract of Mycoplasma arginini by molecular-sieve, anion-exchange and arginine-affinity chromatographies. The purified enzyme was composed of 2 identical sub-units with a molecular weight of 45.000 and had a pI of 4.7. Its Vmax value and Km value for L-arginine were estimated to be 50 units/mg protein and 0.2 mM, respectively. It exerted maximal enzyme activity at pH 6.0-7.5 and at 50 degrees C. The arginine deiminase was stable at neutral pH. When injected i.v. into mice, the half-life of the arginine deiminase in blood was about 4 hr. In culture, the enzyme strongly inhibited the growth of 6 kinds of mouse tumor cell lines by depleting L-arginine in the culture media. When the in vivo growth-inhibitory activity of arginine deiminase was tested for the 6 tumor cell lines, i.p. administration of the purified enzyme effectively prolonged the survival time of the mice injected with all kinds of the tumor cell lines. Especially, the in vivo growth of a hepatoma cell line, MH134, was completely prevented by the daily administration at a dose of 0.2 mg/mouse for 14 days. These results raise the possibility of the use of the arginine deiminase derived from Mycoplasma arginini as a new anti-tumor drug.
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PMID:In vivo anti-tumor activity of arginine deiminase purified from Mycoplasma arginini. 156 92

Proteins resistant to proteinase K are rare because of the potency, wide pH optimum, and low peptide bond specificity of this enzyme. Previously, only the prion proteins associated with transmissible spongiform encephalopathies, possibly related proteins in the mollicute Spiroplasma mirum, and proteinase K itself have been reported. We identified a new proteinase K-resistant protein, p40-pr, in two strains of Mycoplasma hyorhinis and in extracts of these organisms. p40-pr's are similar to prion proteins in their resistance to high doses of proteinase K and in the reversal of this resistance by strong denaturing conditions. However, p40-pr's were distinct immunologically, in relative molecular mass, and in their method of extraction. Two immunologically related forms of p40-pr were identified on sodium dodecyl sulfate (SDS) gels and Western immunoblots, a 40-kDa species in boiled samples and a 120-kDa species dissociable by boiling in SDS. Reduction with 2-mercaptoethanol did not affect the mass of p40-pr's or the 120-kDa forms. The development of proteinase K resistance of p40-pr correlated to age-dependent increases in organism protein-lipid ratios. p40-pr-like proteinase K-resistant proteins of 46 to 50 kDa were identified in four of eight additional species of the class Mollicutes but not in S. mirum. However, these mycoplasmal proteins did not react with antibody to the denatured 40-kDa form of M. hyorhinis p40-pr purified by electroelution. The chromatographically purified 46-kDa proteinase K-resistant protein of Mycoplasma orale was an arginine deiminase.
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PMID:Identification and characterization of proteinase K-resistant proteins in members of the class Mollicutes. 199 7

Non-fermenting mycoplasma species deplete culture media for arginine through arginase activity linked to their arginine deiminase pathway, resulting in proliferation arrest and cell death in mycoplasma-contaminated cell cultures. The presence of only 2-3 Mycoplasma (M.) arginini-contaminated T cells in a one-way allogeneic mixed-lymphocyte culture (MLC) significantly inhibits development of cytotoxic T-cell activity. Likewise, strong degrees of inhibition are observed after addition of nanogram doses of M. arginini extracts (MAE) to MLC or cell proliferation cultures. M. arginini-induced cell inhibition can be reversed by addition of excess arginine to the culture medium. Antisera raised against non-fermenting, but not against fermenting, mycoplasma species block the inhibitory effect of MAE. SDS-PAGE separation of MAE disclosed a broad band at 60 kDa which contained arginase activity when assayed in MLC and cell proliferation culture. SDS-PAGE followed by western blotting and reaction with antisera raised against non-fermenting mycoplasma species demonstrated a band at 43 kDa common for these micro-organisms.
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PMID:Inhibitory effect of mycoplasma-released arginase. Activity in mixed-lymphocyte and tumour cell cultures. 214 42

Two kinds of growth-inhibitory substances were found in culture of a Rous sarcoma virus-transformed rat liver cell line, RSV-BRL. The two substances were purified from the serum-free culture medium and identified as transforming growth factor beta 1 and Mycoplasma-derived arginine deiminase (EC 3.5.3.6), respectively. The arginine deiminase was an acid-labile but dithiothreitol-resistant protein with a molecular weight of 45,000 and pI 4.7. Its Km value for L-arginine was 0.3 mM, which is about 30 times lower than that of bovine liver arginase. It was stable and active under culture conditions. When added into cultures, the arginine deiminase inhibited the growth of various human cancer cell lines at a dose of 5 ng/ml or higher by depleting L-arginine in the culture media. This effective dose was about 1000 times lower than that of bovine liver arginase. These results suggested the possibility of chemotherapeutic use of arginine deiminase for human cancers.
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PMID:Potent growth inhibition of human tumor cells in culture by arginine deiminase purified from a culture medium of a Mycoplasma-infected cell line. 216 40


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