Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proton transfer between the Cys25 and His159 residues in the active centre of the proteolytic enzyme papain is investigated with the Hartree-Fock SCF direct reaction field method. The active centre is treated quantum mechanically, while the environment is represented by interacting partial charges and polarizabilities. All protein atoms around the active site are included explicitly in the calculations. In this way a complete description is given of both the electrostatic and the dielectric properties of the enzyme. The protein matrix stabilizes the zwitterionic form of Cys-His, which is thought to be the catalytically active state much more than the neutral configuration. The most important contribution to the stabilization comes from the alpha-helix to which Cys25 is attached; more than half of its effect is due to the backbone atoms of Cys25 itself. Other important factors are the Asn175 side-chain and the solvent. Solvent effects are estimated by means of Monte Carlo calculations of crystal water molecules that are located near the active site. The total energies of the neutral and zwitterionic structures are similar, confirming the idea that a zwitterion can exist in the active centre of papain. The energy difference, however, is sensitive to the geometry of the active site, suggesting that the two structures are in thermal equilibrium. Classical analogues of the quantum mechanical interaction energy, employing point charge representations of the active site, are found to be quite useful. The dielectric behaviour of the protein is much more complicated than is implicated in dielectric constant models; force fields that do not include an atomic level representation of electronic polarization are inadequate.
J Mol Biol 1989 Mar 05
PMID:The active site of papain. All-atom study of interactions with protein matrix and solvent. 253 81

A cysteine proteinase from epimastigotes of Trypanosoma cruzi, Tul 2 stock, has been purified to homogeneity from cell-free extracts obtained by freezing and thawing, by a procedure involving ammonium sulfate fractionation, DEAE-Sephacel chromatography, and gel filtration on Sephadex G-200; when necessary, further purification was attained by fast protein liquid chromatography on Mono Q and Superose 6 columns. The purified enzyme was strongly inhibited by leupeptin, antipain and chymostatin (I50 values of 0.25, 0.75 and 1 microM, respectively), little inhibited by elastatinal, and unaffected by pepstatin A. The enzyme is a glycoprotein, as shown by binding to ConA-Sepharose and elution with alpha-methyl-D-mannopyranoside and alpha-methyl-D-glucopyranoside. Partial amino acid sequences were obtained from the N-terminal end (32 amino acids) of the carbamidomethylated enzyme, and from a tryptic peptide (14 amino acids) of the pyridylethylated enzyme. Both regions show considerable homology with papain and some cathepsins, such as cathepsin L, thus showing that the enzyme belongs to the cysteine proteinase family.
Mol Biochem Parasitol 1989 Feb
PMID:Further characterization and partial amino acid sequence of a cysteine proteinase from Trypanosoma cruzi. 265 12

The hybridoma, 62H3, which secretes a monoclonal IgG2b with anti-HLA-DR specificity, was expanded in pristane-primed BALB/c mice and the antibody was isolated from the ascitic fluid by affinity chromatography on Protein A-Sepharose. The purified IgG2b antibody was tested by an enzyme immunoassay for antibody activity against a panel of 40 self and non-self antigens. It was found to react strongly with beta-galactosidase, actin, glutamate dehydrogenase, rabbit and human IgG and di- and trinitrophenyl groups; and moderately with tubulin, insulin and phosphorylcholine; but it did not react with various other self and non-self antigens, such as DNA, albumin, keyhole limpet hemocyanin, hen lysozyme and horseradish peroxidase. Fab and Fc fragments were prepared from this IgG2b by papain proteolysis. The Fab fragment possessed the same spectrum of polyreactivities as the native IgG2b, whereas no activity was detected with the Fc fraction. In order to investigate the properties of the antigen binding site, the actin, TNP and rabbit IgG antibody activities were studied in more detail by enzyme immunoassay, Western blot and immunocytochemistry. The monomolecular nature of this multireactivity was confirmed by immunoabsorption analysis. Furthermore, 62H3 monoclonality was also verified by comparative isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis with other monospecific antibodies. The dissociation constants (Kd) of antigen-antibody equilibria in solution were measured. The Kd for actin was 1.11 +/- 0.24 x 10(-5) M and the Kd for TNP-BSA was 8.7 +/- 0.51 x 10(-7) M. No interaction with rabbit IgG could be detected in solution. These findings raise the question of the possible implication in autoimmune pathology or in normal physiology of IgG class polyspecific antibodies with solid-phase restricted cross-reactive rheumatoid factor activity.
Mol Immunol 1989 Jun
PMID:Immunochemical studies of a murine polyreactive IgG2b autoantibody with rheumatoid factor activity. 277 Jul 48

Single crystals of the core protein of the cellulase cellobiohydrolase II have been grown in polyethylene glycol 6000 with the hanging drop method. Successful crystallization occurred only when 82 amino acids were removed from the N terminus by papain cleavage. Crystals belong to the space group P2(1) and have cell constants a = 49.1 A, b = 75.8 A, c = 92.9 A, beta = 103.2. The diffraction pattern extends to better than 2.0 A.
J Mol Biol 1989 Sep 05
PMID:Crystallization of the core protein of cellobiohydrolase II from Trichoderma reesei. 281 Mar 67

Membranes of human spleen cells were hydrolyzed by papain and the extracellular portions of HLA antigen molecules isolated by monoclonal antibodies fixed on Sepharose. The isolated proteins were spin-labeled by TEMPO-dichlorotriazine. The values of rotational correlation times (tau) of spin-labeled proteins were calculated using dependencies of magnetic parameters found from ESR spectra vs viscosity at constant temperature. The tau-values were equal to 8 nsec for class I molecules and 14 nsec for class II molecules. These values were significantly lower than those predicted for a rigid sphere with dimensions equal to the extracellular portions of HLA molecules (20 nsec). This fact suggests the existence of flexibility in poly-functional HLA molecules, which seems to be important for their biological activity. In this respect, extracellular portions of HLA molecules resemble flexible Fc fragments (tau = 12 nsec) and differ from rigid Fab fragments (tau = 20 nsec) of immunoglobulins G. The rotation of the oligosaccharide chains attached to HLA molecules is restricted.
Mol Immunol 1987 Jul
PMID:Extracellular portions of HLA antigens are not compact globulae. 282 87

Membranes of human splenocytes were hydrolyzed by papain and extracellular portions of class I and class II HLA antigen molecules were isolated by monoclonal antibodies fixed on Sepharose 4B. The isolated proteins were spin-labeled by TEMPO-dichlorotriazine and the values of rotational correlation times (tau) of labeled proteins were found using dependencies of ESR spectra parameters vs viscosity at constant temperature. The tau-values were equal to 8 ns for class I molecules and 14 ns for class II molecules. These values are 2-3 times lower than predicted for a rigid ellipsoid with mol wt. 50 kDa (about 20 ns). This fact suggests the existence of flexibility of HLA molecules which seems to be important for their biological activity. In this respect extracellular portions of HLA antigen molecules resemble flexible Fc fragments (tau = 12 ns) and differ from rigid Fab fragments (tau = 20 ns) of immunoglobulins G. The values of tau of spin-labeled proteins adsorbed from membrane hydrolysates on IgG-column was equal to 6.5 ns. The proteins adsorbed on lentil lectin column (after isolation of HLA proteins) have the tau-values equal to 9 ns.
Mol Biol (Mosk)
PMID:[Intramolecular mobility of human major histocompatibility complex protein. A spin-label study]. 282 88

The repair of articular cartilage following papain injection into the knee joint of the guinea pig was studied by light and electron microscopy, as well as by autoradiography using tritiated thymidine. Papain injection rapidly produced complete degradation of cartilage proteoglycan. Although a number of chondrocytes were also destroyed, the remaining chondrocytes showed mitotic cell division with resultant formation of cell clusters. Such chondrocytic regeneration, however, did not contribute significantly to the repair of cartilage tissue. On the other hand, mesenchymal cells proliferated from the transition zone and extended over the surface of the damaged cartilage. At the peripheral portion of the articular surface, they migrated and differentiated into chondrocytes with the formation of abundant intercellular matrix to produce hyaline cartilage. From these findings, it was apparent that mesenchymal cells in the transition zone were actively engaged in the repair of articular cartilage.
Virchows Arch B Cell Pathol Incl Mol Pathol 1986
PMID:Papain-induced changes in the guinea pig knee joint with special reference to cartilage healing. 287 20

The type III Fc receptors present on or secreted by a series of group C and G streptococcal strains were studied. All strains capable of binding radiolabeled human IgG were shown to do so via an antigenically related Fc receptor. Treatment of any of the bacterial strains with papain or trypsin resulted in solubilization of Fc receptor activity. The pattern of Fc receptor activity recovered following enzyme treatment was not uniform. Differences were observed both between group C and G strains as well as within group C and G strains. Analysis of secreted Fc receptors indicated the presence of five molecular forms of Fc receptor. Each form was present at some level in the supernatant of every group C and G strain studied. The relative concn of each form of receptor secreted varied from strain to strain. The Fc receptor activity secreted by each strain demonstrated a similar affinity for the Fc region of human IgG and all were antigenically related. These results suggest that there is a family of closely related Fc receptors associated with group C and G streptococcal strains.
Mol Immunol 1986 Aug
PMID:Comparison of type III Fc receptors associated with group C and group G streptococci. 294 12

The binding sites of rat IgE to mast cell receptor were investigated by the use of proteolytic fragments and a monoclonal antibody to epsilon chain (MARE-1). Three main fragments were characterized by short-time papain digestion of IgE: F(ab')2-E, a fragment related to the C, 4 domain, and an asymmetric fragment corresponding probably to an IgE molecule with one proteolyzed C, 3 domain. Neither F(ab')2-E nor C, 4 could interfere with the binding of IgE to rat mast cells. These two fragments did not show significant polymerization upon heating at 56 degrees C, while large amounts of polymers were produced from whole IgE, MARE-1 monoclonal antibody was found to react neither with F(ab')2 nor with C, 4, thereby suggesting its interaction with the C, 3 domain. MARE-1 was found to inhibit partially (about 55%) the binding of IgE to its receptor. Taken together the results indicate that the binding sites of IgE to rat mast cell receptor are located within the C, 3 domain. In addition, isolation of the C, 4 domain will be useful to evaluate its participation in the affinity of IgE to receptors of other cells such as lymphocytes or macrophages.
Mol Immunol 1987 Feb
PMID:Studies of the IgE binding sites to rat mast cell receptor with proteolytic fragments and with a monoclonal antibody directed against epsilon heavy chain: evidence that the combining sites are located in the C epsilon 3 domain. 295 98

An IgGl(lambda) Mot myeloma protein showed a unique susceptibility toward papain digestion. The Fab fragment of Mot was more digestible with papain than the Fc fragment. This phenomenon was found to occur by unusual cleavage of the Fd fragment with papain. Determination of the complete primary structure of the V region of the H chain of Mot identified two papain cleavage sites in the second complementarity-determining region (CDR). Amino acid sequence of the cleavage sites was Ser(55)-Asp-Asp-Argdecrease-Thr-Thr-Tyr-Gly-Pro-Argdecrease- Ser-Gln- (decrease = cleavage site). In the vicinity of these cleavage sites, many hydrophilic and polar residues are present and the predicted secondary structure near these cleavage sites suggested that this region was exposed on the surface of the molecule, and that the unusual papain cleavage of the IgG Mot might be caused by a unique conformation of the molecule, making it highly susceptible to enzyme digestion.
Mol Immunol 1986 Feb
PMID:Amino acid sequence of the variable region of heavy chain in immunoglobulin (Mot) having unusual papain cleavage sites. 308 50


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