Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new rapid method for the quantitative and routine determination of free amino groups in intact pure proteins has been developed. Primary amino groups are labeled with fluorescamine and the labeled groups are detected by absorption spectroscopy in the range 375-390 nm. The amino group concentration can be determined in a few minutes without hydrolyzing the labeled protein and extracting a lysine derivative. The method was tested with the following proteins: lysozyme, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, ribonuclease, ribonuclease-S-peptide, and alphasl-casein B. Application of this method to the estimation of available lysine is discussed.
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PMID:New method for determination of free amino groups in intact pure proteins: relationship to available lysine. 99 78

The hydroxyl groups of poly(ethyleneglycol) have been esterified (partly) with a number of carboxylic acids. When these esters are included in dextranpoly(ethyleneglycol)-water biphasic systems the partitions of proteins and membranes between the two phases (and the interface) are in some cases strongly affected. The affinity of serum albumin for the poly(ethyleneglycol)-rich phase is strongly increased when the fatty acid group consists of more than 10 carbon atoms. The partition also depends on the number of double bonds in the fatty acid. A corresponding relationship is found for membranes from spinach chloroplasts. The partitions of ovalbumin, lysozyme (EC 3.2.1.17) and ribonuclease (EC 3.1.4.22) are not influenced by the fatty acid esters. Esters of dibasic carboxylic acids show a minute but marked effect on the partition of proteins in general while malate and tartrate esters affect strongly the partition of chloroplast membranes. The partitions of both proteins and membranes are influenced by poly(ethyleneglycol) deoxycholate. Experiments with malate dehydrogenase (EC 1.1.1.37), lactate dehydrogenase (EC 1.1.1.27), fumarase (EC 4.2.1.2), enolase (EC 4.2.1.11) and glutamate-ocaloacetate transaminase (EC 2.6.1.1) show that their partitions, measured on enzymic activity basis, is changed when esters of benzoic, linolenic, tartaric or deoxycholic acid are included in the biphasic system. The mechanism behind the effect of the esterified poly (ethyleneglycol) on the partition of biomaterial, in this type of aqueous biphasic systems, is discussed in terms of a direct binding of the esters to the partitioned material.
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PMID:The effect of poly(ethyleneglycol) esters on the partition of proteins and fragmented membranes in aqueous biphasic systems. 99 68

The interaction of metal cations with single chain globular proteins produces volume increases, the magnitude of which is determined primarily by the ion and to a lesser extent by the protein. The cations are listed in ascending order of volume change: K(I) less than Mg(II) less than Sr(II) less than Ca(II) less than Co(II) less than Ni(II) less than Cd(II) less than Zn(II) less than Cu(II) less than Pb(II). This sequence held for all cation-protein systems investigated except for Cd(II) which produced a slightly larger volume effect than Zn(II) with lysozyme. The volume changes attributed to protein-cation interaction are positive and range from 8 ml/10(5) g of protein for the reaction on 0.05 M KNO3 with bovine plasma albumin to 2320 ml/10(5) g of protein produced by the 0.20 M Pb(NO3)2-myoglobin system. A similar classification scheme was not possible for the proteins. For example, volume increases of 45, 50, 80 and 95 ml/10(5) g of protein were produced when 0.05 M Mg(II) reacted with bovine serum albumin, ovalbumin, sperm whale myoglobin and lysozyme, respectively. However, when 0.2 M Pb(II) was the reactant the values were 1930, 846, 2320, and 1120 ml/10(5) g of protein. Volume effects produced by Cr(III), Al(III) and Fe(III) were determined, but the calculated results are considered dubious because the volume changes are a complicated function of protein-cation and protein-proton interaction.
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PMID:Protein-metal ion interaction: volume effects produced by the interaction of proteins with metal ions. 105 36

The hydrophobic nature of proteins is characterized by a degree of 2-p-toluidinonaphthalene-6-sulphonate (TNS) affinity to them and is pronounced quantitatively in the semi-saturated (C1/2) concentrations. This index correlates directly with the position of TNS emission maximum after the binding with proteins and reversely with the yield of fluorescence. The preparations of phosphofructokinase, lactate dehydrogenase, xantinoxidase, glyceratekinase, lysozyme, RNase during the long (1-2 h) contact with TNS change the values C1/2, that evidences for interaction with the hydrophobic indicator of new structures of protein molecule or for a change in the nature of its linkage itself. An attempt is made to characterize the accessible for TNS hydrophobic nature of individual proteins by a coefficient of molar hydrophobic nature which unites three mentioned characteristics. Serum albumin, insulin, glucogon, alpha chemotrypsin, DNase are most hydrophobic, pyruvate kinase, aldolase, urease, RNase--least hydrophobic, Glycerate kinase, pyruvate decarboxylase, phosphofructokinase, lactate dehydrogenase, alcohol dehydrogenase, xanthinoxidase, trypsin, lysozyme are in intermediate position.
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PMID:[Comparative characteristics of hydrophobic nature of certain proteins by their interaction with 2-p-toluidinonaphthalene-6-sulfonates]. 120 4

1. The reactivity of alpha-chymotrypsin toward p-nitrophenylacetate has been studied in dimethylformamide, dimethylsulfoxide, formamide and methylacetamide. p-Nitrophenol is liberated in dimethylsulfoxide only. 2. The reactions of alpha-chymotrypsin in dimethylsulfoxide are characterized by the same kinetic and equilibrium constants with either the p-nitrophenyl esters of straight chain carboxylic acids (from acetic to n-caprylic) or with the "specific substrate", N-carbobenzoxy-DL-phenylalanine p-nitrophenyl ester. This signifies that reactions of alpha-chymotrypsin in dimethylsulfoxide, unlike those in aqueous medium, have no specificity toward su-strate structure. 3. The stoichiometry of alpha-chymotrypsin reactions in dimethylsulfoxide was shown to be about five moles of substrate per mole of enzyme. After attaining this stoichiometry, the reaction is completed. 4. Optical rotatory dispersion spectra indicate that in non-aqueous media alpha-chymotrypsin undergoes a large conformational transition which results in a random coil. 5. Chymotrypsinogen, trypsin, trysinogen, lysozyme and serum albumin react with p-nitrophenylacetate in dimethylsulfoxide at rates which are approximately equal to those of alpha-chymotrypsin. Thus, the "activity" of alpha-chymotrypsin in dimethylsulfoxide toward p-nitrophenylacetate does not differ from the "activity" of other proteins, some of which are not even hydrolytic enzymes.
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PMID:The reactions of alpha-chymotrypsin and related proteins with ester substrates in non-aqueous solvents. 120 14

Nuclear magnetic quadrupole relaxation appears to be a general method for studying the binding of anions to proteins. This is shown by the increase in transverse quadrupole relaxation rate of 35Cl- and 81Br- in the presence of horse liver alcohol dehydrogenase, lysozyme, trypsin, alpha-chymotrypsin, human carbonic anhydrase, fructose-1,6-bisphosphate aldolase and human serum albumin. Of the many possible binding sites at the surface of a protein (e.g. positively charged amino acid side-chains) only a few account for the main part of the relaxation enhancement. This is shown by the decrease in 35Cl- and 81Br- relaxation rate on addition of functional ligands. Large, kinetically inert, complex anions like Pt(CN)2-4 and Au(CN)-2 are found to act as strong competitors towards halogen ions for the high-affinity anion binding sites of a number of proteins. Titrations with complex anions following the 35Cl- or 81Br- relaxation rates are found to be helpful in attempts to elucidate binding mechanisms. Especially, the complex anions may be useful probes for the discrimination between general and metallic anion binding sites in proteins and they also permit correlation of information from X-ray investigations of crystals with that from physical measurements in solution. From the change in halide ion quadrupole relaxation rate on addition of strongly binding ligands the quadrupole coupling constants of the high affinity Cl- and Br- binding sites are estimated using certain assumptions. It is found that for several proteins, comprising the metal-free proteins but also alcohol dehydrogenase and Escherichia coli alkaline phosphatase, the 35Cl quadrupole coupling constants have approximately the same values. For some other metallo-proteins like carbonic anhydrase and a zinc - serum-albumin complex considerably greater quadrupole coupling constants were obtained. The estimated quadrupole coupling constants are used as a basis for a discussion of the interactions involved in anion-protein interactions.
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PMID:Pt(CN)2-4 and Au(CN)-2: potential general probes for anion-binding sites of proteins. 35Cl and 81Br nuclear-magnetic-resonance studies. 120 23

Under defined conditions, in the presence of 10 mg/ml of bovine serum albumin, cauda epididymal rat spermatozoa displayed vigorous motility, and a high proportion (81%) of eggs were fertilized. In contrast, no fertilization was observed after omission of albumin, or replacement of the protein by 10 mg/ml of cytochrome c, beta-globulin, gamma-globulin, hemoglobin, lysozyme, and polyvinylpyrrolidone, and 5 mg/ml of ribonuclease. However, high motility occurred in suspensions containing 3 x 10(6) spermatozoa/0.1 ml of medium with cytochrome c, beta-globulin, or gamma-globulin. In medium with 1 mg/ml of ovalbumin, 7% (2/29) eggs were fertilized. Use of defatted albumin resulted in a higher rate of fertilization than unmodified albumin (87 vs 70%), and this difference approached statistical significance. No fertilization was obtained in the presence of albumin presaturated with cholesterol. These results suggest that: (a) rat sperm cells failed to capacitate in the absence of albumin; (b) the protein exerted more than a nonspecific macromolecular effect; and (c) lipids associated with albumin may modify its ability to promote sperm capacitation.
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PMID:Influence of serum albumin on the fertilizing ability in vitro of rat spermatozoa. 125 Aug 65

The unfolded states of serum albumin, lysozyme and ribonuclease denatured in GuHCl with their disulfide bridges intact or reduced and carboxyamidomethylated have been compared by their circular dichroism, second-derivative and difference spectra in the ultraviolet region. Results obtained indicate that although the secondary structures of denatured proteins with intact disulfides are largely destroyed, they still have considerable ordered conformation even in 6 mol/L guanidinium chloride as indicated by the differences in the extents of exposure of the aromatic residues compared to the denatured proteins without the native disulfide bonds.
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PMID:Disulfide containing proteins denatured in 6 mol/L guanidinium chloride are not completely unfolded. 128 48

The preferential interactions of bovine serum albumin, lysozyme, chymotrypsinogen, ribonuclease A, and beta-lactoglobulin with polyethylene glycols (PEGs) of molecular weight 200-6,000 have been measured by dialysis equilibrium coupled with high precision densimetry. All the proteins were found to be preferentially hydrated in all the PEGs, and the magnitude of the preferential hydration increased with increasing PEG size for each protein. The change in the chemical potentials of the proteins with the addition of the PEGs had highly positive values, indicating a strong thermodynamic destabilization of the system by the PEGs. A viscosity study of the PEGs showed them to be randomly coiled polymers, as their radii of gyration were related to the molecular weight by Rg = aM0.55. The thickness of the effective shell impenetrable to PEG around protein molecules, calculated from the preferential hydration, was found to vary with PEG molecular weight in similar fashion as the PEG radius of gyration, supporting the proposal (Arakawa, T. & Timasheff, S.N., 1985a, Biochemistry 24, 6756-6762) that the preferential exclusion of PEGs from proteins is due principally to the steric exclusion of PEG from the protein domain, although favorable interactions with protein surface residues, in particular nonpolar ones, may compete with the exclusion. These thermodynamically unfavorable preferential exclusion interactions lead to the action of PEGs as precipitants, although they may destabilize protein structure at higher temperatures.
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PMID:Steric exclusion is the principal source of the preferential hydration of proteins in the presence of polyethylene glycols. 130 92

An inhibitory protein for the 20S proteasome (also known as macropain, the multicatalytic proteinase complex and 20S proteinase) has been purified from bovine red blood cells. The inhibitor has an apparent molecular weight of 31,000 on SDS-PAGE and appears to form multimers under nondenaturing conditions. This protein inhibited all three of the putatively distinct catalytic activities of proteasome A (the active form of the proteinase) characterized by the hydrolysis of synthetic peptides such as Z-VLR-MNA, Z-GGL-AMC or Suc-LLVY-AMC and Z-LLE-beta NA. The inhibitor also prevented the hydrolysis of large protein substrates such as casein, lysozyme and bovine serum albumin. Proteasome L (the latent form of the proteinase) does not degrade these large protein substrates, but does hydrolyze the three synthetic peptides at rates similar to those by proteasome A. The inhibitor inhibited only two of these peptidase activities of proteasome L (hydrolysis of Z-GGL-AMC and of Z-LLE-beta NA or Suc-LLVY-AMC); it had no effect on the hydrolysis of Z-VLR-MNA. The inhibitor was specific for inhibition of the proteasome and had no effect on the activity of any other proteinase tested including trypsin, chymotrypsin, papain, subtilisin and both isoforms of calpain. Kinetic analysis indicates that the inhibitor interacted with the proteasome by a mechanism involving tight-binding. Because the proteasome appears to be a key component of the ATP/ubiquitin-dependent pathway of intracellular protein degradation, the inhibitor may represent an important regulatory protein of this pathway.
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PMID:Purification and characterization of a protein inhibitor of the 20S proteasome (macropain). 131 59


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