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: EC:3.5.1.1 (asparaginase)
2,695 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

S-Carboxymethylated L-asparaginase was digested with trypsin and the resulting peptides were isolated by using gel filtration, ion exchange column chromatography and paper chromatography. Among the peptides thus isolated, 27 peptides were considered not to overlap and the sum of the amino acids from these 27 peptides is in good agreement with amino acid composition of the enzyme. The amino acid sequences of the peptides were determined by fragmentation with various enzymes and subtractive Edman degradation.
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PMID:Amino acid sequences of the tryptic peptides from carboxymethylated L-asparaginase from Escherichia coli. 38 70

Acinetobacter glutaminase-asparaginase was chemically modified by succinylation and glycosylation with glycopeptides from human fibrin and gamma-globulin. These modifications markedly prolonged the half-lives of the enzyme in mice, rats, and rabbits. The plasma half-life in mice increased with decreasing isoelectric point. Glycosylation caused greater prolongation in rodents than succinylation. The kinetic properties of the modified enzymes were unchanged. Succinylation protected the enzyme from trypsin digestion. Glycosylated preparations had less heat inactivation than native and succinylated enzyme. Sedimentation equilibrium studies on a succinylated preparation showed reversible dissociation to a dimer (71, 400 g/mol) with an association constant of 1.3 times 10-6 liters/mol. This dissociation was identical with native enzyme, except for a 3% increase in molecular weight due to succinate groups. Sedimentation equilibrium studies on glycosylated preparations showed mixtures of molecular weight from 60, 000 to over 180, 000. Gel filtration and active enzyme sedimentation showed active polymers, but no active species smaller than tetramer.
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PMID:Biologic and physical properties of succinylated and glycosylated Acinetobacter glutaminase-asparaginase. 112 47

We show that a non-inhibitory monoclonal antibody (MAB) can be selected that provides substantial and sustained protection against proteolytic inactivation of L-asparaginase by trypsin. Of six non-inhibitory, high affinity, monoclonal antibodies to L-asparaginase, one afforded approximately 70% protection. Inactivation of L-asparaginase is associated with a single cleavage adjacent to lysine-29 that results in loss of an N-terminal fragment with a calculated MW of 2,647. The protective MAB prevented this trypsin cleavage. The products of gene fusions of "humanized" fragments of such antibodies and L-asparaginase could have increased clinical utility.
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PMID:Monoclonal antibodies can protect L-asparaginase against inactivation by trypsin. 136 89

Oxidized dextrans of increasing molecular weight were bound covalently to Erwinia carotovora asparaginase. The resulting conjugates retained 50% of their enzyme activity and showed marked resistance to proteolysis by trypsin and chymotrypsin and inactivation by asparaginase-specific antibody. When tested in-vivo, the larger molecular weight conjugates showed prolonged circulatory survival in both immune and non-immune animals and failed to elicit full type III hypersensitivity or anaphylactic reactions when injected into sensitized guinea-pigs. Rabbits could tolerate multiple doses of the asparaginase conjugate without developing an immunity to the enzyme. A conjugate showing increased circulatory half-life and lowered antigen reactivity should have therapeutic potential.
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PMID:Soluble asparaginase-dextran conjugates show increased circulatory persistence and lowered antigen reactivity. 242 75

The commercial preparation of 1-asparaginase was incorporated into liposomes formed from soybean phospholipids (asolectin). The inside phase volume of liposomes did not exceed 1% as calculated using fluorescence dye calcein but the efficiency of the enzyme incorporation into liposomes reached approximately 60%. The enzyme was adsorbed on outside surface due to electrostatic and hydrophobic interactions. The Km value of immobilized 1-asparaginase (2.7 X 10(-5)M) did not exceed considerably the Km values of free enzyme (1.8 X 10(-5)M) when l-asparagine was used as a substrate. The incorporation of 1-asparaginase into asolectin liposomes led to considerable increase in the enzyme thermostability at 70 degrees and also to an increase in its sensitivity to proteases and, particularly, to trypsin. The half-life periods of free and immobilized enzymes were practically similar in buffer solutions. However, the half-life period of immobilized l-asparaginase in blood serum was more than 6-fold higher as compared with that of the free enzyme.
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PMID:[Characteristics of immobilization and catalytic properties of the Soviet commercial preparation of L-asparaginase in liposomes composed of soybean phospholipids]. 372 73

Benzoyl- and isopentenoyl phosphoric triamides (BPA and IPA) strongly inhibited urease activities from jack bean, soybean, watermelon seed, Proteus mirabilis, P. rettgeri, P. vulgaris, Mycobacterium smegmatis, and Ureaplasma urealyticum. Their I50 values (the final concentration causing 50% inhibition), independent of enzyme source, were 2-21 nM, which are about 1,000-fold lower than that of caprylohydroxamic acid, one of the most potent urease inhibitors. ATP-urea amidolyase activity was inhibited 50% by BPA at a higher concentration of 0.28 mM, but was not affected by IPA even at 1.3 mM. Thirteen kinds of hydrolases (trypsin, chymotrypsin, thermolysin, leucine aminopeptidase, papain, lipase, alpha-amylase, glucuronidase, asparaginase, arylsulfatase, alkaline phosphatase, acid phosphatase, and true cholinesterase), two oxidoreductases (catalase and alcohol dehydrogenase), three transferases (glutamic-oxaloacetic aminotransferase, gamma-glutamyl transpeptidase, and arylsulfotransferase) and two kinases (pyruvate kinase and creatine kinase) were not affected at all even at 1 mM BPA and IPA. Exceptionally, pseudo-cholinesterase from human serum was inhibited by BPA and IPA, whose I50 values were 70 nM and 10 muM, respectively, using acetylthiocholine as a substrate. These values increased to 0.55 muM and 54 muM, respectively, when acetylcholine was used as a substrate. These results show that N-acylphosphoric triamides potently and specifically inhibit urease activity at concentrations of nM order.
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PMID:Specific inhibition of urease by N-acylphosphoric triamides. 384 42

The carboxymethylated L-asparaginase from Escherichia coli A-1--3 was fragmented with cyanogen bromide and the resulting peptides were isolated by using gel filtration on Sephadex G-50 and column chromatography on DE-52. The amino acid sequences of the 7 cyanogen bromide peptides thus obtained were established completely or partially by further fragmentation with trypsin, chymotrypsin and pepsin, and the Dansyl Edman method. Based on the above results and the complete sequences of the tryptic peptides from the carboxymethylated L-asparaginase reported in the previous paper, the whole sequence of the enzyme was established. The reported sequence consists of 321 amino acid residues and its calculated molecular weight is 34 080.
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PMID:The primary structure of L-asparaginase from Escherichia coli. 676 94

Mouse myeloid leukemic M1 cells can be induced to differentiate into macrophages and granulocytes in vitro by a factor(s) stimulating differentiation of the cells (D-factor), which is suggested to be a glycoprotein. On the other hand, growth and differentiation of normal precursor cells of macrophages and granulocytes can be stimulated by a glycoprotein termed colony-stimulating factor (CSF). Mouse fibroblast L929 cells were found to produce both the D-factor and CSF. The properties of the D-factor and CSF and the roles of carbohydrates in the molecules of these factors were examined using tunicamycin, a specific inhibitor of asparaginase-linked glycosylation. Although both the D-factor and CSF were produced by L-cells in usual medium containing fetal calf serum, production of D-factor, but not CSF, was reduced by omission of serum from the medium. The activity of the D-factor was slightly decreased by treating the L-cells with tunicamycin (0.5 microgram/ml) in the presence of 2% fetal calf serum, without any decrease in CSF activity. Conditioned medium of L-cells incubated with or without tunicamycin was fractionated by gel filtration on a Sephadex G-200 column. Normal D-factor appeared as a single peak with an apparent molecular weight of 67,000. D-factor produced in the presence of tunicamycin had an apparent molecular weight of 25,000. On the other hand, most of the CSF was eluted in the void volume, even when it was produced in the presence of tunicamycin. The D-factor produced in the presence of tunicamycin was more sensitive than normal D-factor was to trypsin or heat treatment at 70 degrees. The CSF produced in the presence of tunicamycin was resistant to these treatments. These results indicate that the D-factor is distinct from CSF. Furthermore, the results suggest that the D-factor produced by L-cells is also a glycoprotein and that, although carbohydrate is not essential for production or activity of the D-factor, it contributes to stabilizing the protein portion of D-factor.
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PMID:Effect of tunicamycin on production by mouse fibroblast L929 cells of the factor-stimulating differentiation of mouse myeloid leukemic cells and the colony-stimulating factor. 697 52

We have demonstrated that a trypsin sensitive enzyme such as L-asparaginase can be rendered trypsin resistant by genetically fusing its gene with that of a single-chain antibody derived from a preselected monoclonal antibody capable of providing protection against trypsin. The chimeric L-asparaginase retained 75% of its original activity upon exposure to trypsin, whereas the native unprotected L-asparaginase control was totally inactivated.
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PMID:Engineering resistance to trypsin inactivation into L-asparaginase through the production of a chimeric protein between the enzyme and a protective single-chain antibody. 764 79

Procedures are described for linking monomethoxypoly(ethylene glycol) (mPEG) to both epsilon and alpha amino groups of lysine. The lysine carboxyl group can then be activated as a succinimidyl ester to obtain a new mPEG derivative (mPEG2-COOSu) with improved properties for biotechnical applications. This branched reagent showed in some cases a lower reactivity toward protein amino groups than the linear mPEG from which it was derived. A comparison of mPEG- and mPEG2-modified enzymes (ribonuclease, catalase, asparaginase, trypsin) was carried out for activity, pH and temperature stability, Km and Kcat values, and protection to proteolytic digestion. Most of the adducts from mPEG and mPEG2 modification presented similar activity and stability toward temperature change and pH change, although in a few cases mPEG2 modification was found to increase temperature stability and to widen the range of pH stability of the adducts. On the other hand, all of the enzymes modified with the branched polymer presented greater stability to proteolytic digestion relative to those modified with the linear mPEG. A further advantage of this branched mPEG lies in the possibility of a precise evaluation of the number of polymer molecules bound to the proteins; upon acid hydrolysis, each molecule of mPEG2 releases a molecule of lysine which can be detected by amino acid analysis. Finally, dimerization of mPEG by coupling to lysine provides a needed route to monofunctional PEGs of high molecular weight.
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PMID:A branched monomethoxypoly(ethylene glycol) for protein modification. 771 Nov 5


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