Phylogenesis of the general structure of immunoglobulins.

The study of the general structure of macroglobulins and 7S (IgG) immunoglobulins of frog and tortoise by relaxation methods shows the rotational correlation time of 7S immunoglobulins to be 67–68 nsec whereas that of macroglobulins of frog is 135 nsec and of tortoise is 103 nsec. Experimental values of rotational correlation time for 7S immunoglobulins are close to those calculated for the model of this molecule approximated by the rigid rotational ellipsoid and lower than those estimated for macroglobulins. This indicates that frog and tortoise 7S immunoglobulins have a fairly compact general structure with no marked intramolecular rotational freedom for high-molecular fragments, whereas macroglobulins possess it to a limited extent. It is seen from our evidence on the rigidity of 7S immunoglobulins and the limited flexibility of macroglobulins in amphibia and reptiles, as compared to previous data on the limited flexibility of carp macroglobulins and on the pronounced flexibility of IgG and IgM of mammals, that the general structure becomes more flexible on passing from lower vertebrates to representatives of a more recent class of mammals. The reported increased flexibility of immunoglobulins accompanied by the progressive evolution of species is likely to provide one of the first indications of the possible directed selection in the course of molecular evolution.     

The evolutionary problems of the family of human and animal macroglobulins]

Studies have been made on physicochemical and immunochemical properties of macroglobulins, as well as of associated with pregnancy glycoproteins, from human subjects, mammals, birds, fishes and invertebrates. It was shown that these proteins exhibit similar composition, structure and capacity to bind proteinases inhibiting the latter. Using immunochemical methods, reactions of antigenic identity of these proteins were investigated. A hypothesis of evolutionary formation of macroglobulin family is discussed.     

Murinoglobulin, a novel protease inhibitor from murine plasma. Isolation, characterization, and comparison with murine alpha-macroglobulin and human alpha-2-macroglobulin

Two glycoproteins having trypsin-protein esterase activity were purified to apparent homogeneity from murine plasma. One was alpha-macroglobulin, a homologue of human alpha-2-macroglobulin, while the other, tentatively named murinoglobulin, did not correspond to any of the known plasma protease inhibitors that have been well characterized in men or other mammals. Murinoglobulin contained about 7.6% carbohydrate and was composed of a single-polypeptide chain of Mr = 180,000 as judged by the equilibrium sedimentation analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Murinoglobulin did not cross-react immunologically with mouse alpha-macroglobulin nor with human alpha-2-macroglobulin. Protease-inhibiting properties of murinoglobulin were compared with those of mouse alpha-macroglobulin and human alpha-2-macroglobulin. All the three proteins inhibited trypsin, papain, and thermolysin, although they differed considerably in both the degree of inhibition and the binding stoichiometry of protease-inhibitor complexes. The two macroglobulins inhibited pepsin at pH 5.5, whereas murinoglobulin was inactivated at this pH. Murinoglobulin was more sensitive to methylamine than the two macroglobulins. No protein corresponding to murinoglobulin was detected in human plasma.     

Isolation and purification of Lpm and alpha-2 M macroglobulins from mink serum]

A procedure for large-scale separation and purification of two mink serum macroglobulins, Lpm and alpha 2M, is described. Individual preparations of each of these macroglobulins were obtained in an immunologically pure state. After precipitation from the serum at 6.5-13% PEG 6000, Lpm and alpha 2M were separated by a pH stepwise gradient elution metal chelate affinity chromatography and purified by chromatographies on Biogel A 1.5 m and DEAE-Trisacryl M. Each of these macroglobulins was tested by counter-immunoelectrophoresis with the corresponding monospecific antiserum. The yields per 100 ml of the source serum were 23-44 mg of Lpm and 7-30 mg of alpha 2M which corresponded to 10-20% of their serum contents. Some of general biochemical properties of mink Lpm and alpha 2M and of all mammalian alpha-macroglobulins are discussed.     

Structure and Role of the Five Glycopeptides of Human IgM Immunoglobulins

Carbohydrate is attached at five sites in the constant sequence region of the µ heavy chain of human IgM. The oligosaccharides are of two kinds, simple and complex and affect the conformation and properties of macroglobulins.     

Evolution of the macroglobulin protein family: from bacteria to primates

Proteins of the macroglobulin family are thioether-containing glycoproteins that act as inhibitors of a wide range of hydrolases, transporters and regulators of cytokine, hormone, lipid and oligonucleotide synthesis. As ancient components of innate immunity, these proteins are involved in folding of endogenous proteins as well as recognition and presentation of exogenous antigens. Interaction of macroglobulins with transmembrane receptors triggers cascades of reactions that regulate energy metabolism, cell division and apoptosis, participate in reproduction and cancerogenesis. A broad spectrum of conformational and functional states of molecules, depending on the type of ligands, and an appropriate set of implemented functions allow us to consider these proteins as key regulators of proteostasis. This review addresses the structure and function of macroglobulin proteins during evolution of organisms staying at different phylogenetic levels.     

The general structure of shark (squalis acantias) and hen (galus domesticus) immunoglobulins

The study of the general structure of macroglobulins and 7S immunoglobulins of shark and hen by the polarisation fluorescence method shows that shark immunoglobulins have a compact general structure whereas 7S hen immunoglobulins have a fairly flexible general structure. It is seen from our evidence, as compared to previous data on other classes, that the general structure becomes more flexibles on passing from cold-blooded to representatives of warm-blooded vertebrates.     

Effect of Dexamethasone and Nitrogen Mustard on the Production of Rheumatoid Factor in Rheumatoid Arthritis

The effect of dexamethasone and nitrogen mustard on the production of rheumatoid factor, as measured by sensitized sheep cell and latex agglutination tests, was studied in 19 patients with classical rheumatoid arthritis. Dexamethasone was given orally in a daily dose of 6-8 mg. which was slowly reduced after a two-week period. Nitrogen mustard was infused in the usual therapeutic dose of 0.3 mg./kg. The level of circulating rheumatoid factor decreased, following administration of each agent, after a latent period of 10 days. The effect was most marked at around 30 days. Dexamethasone was more potent than nitrogen mustard. Both drugs together caused transient disappearance of rheumatoid factor in one patient.It is concluded that dexamethasone and nitrogen mustard have the capacity to suppress the formation of the macroglobulins associated with rheumatoid arthritis.     

The additivity principle in the reaction of angiotensin II and its analogs with antibodies and receptors of glomerular cells from the rat adrenal cortex

The binding of angiotensin II and its analogues (13) to rabbit antibodies and glomerular cell receptors from rat adrenal cortex was studied, using the radioimmunoassay method and radioreceptor analysis. Double modifications introduced into the angiotensin structure were found to increase in an additive fashion its binding to the antibodies and renal cell receptors. The relative binding activity of the analogues carrying a double modification can be assessed if the activities of the analogues with the appropriate single modifications are known. It was concluded that the testing of modifications in the peptide structure for their additivity may provide some insight into the conformational properties of peptides during their binding to the protein.     

Role of proteins of the macroglobulin family in the mechanisms of infection

Information on the properties of proteins of the macroglobulin family taking part in the host protection from viral, fungal and bacterial pathogens is reviewed. High plasticity and polyfunctional character of these proteins makes it possible to realize different protective functions. They inhibit the lysis of the cell wall by binding the hydrolases of the pathogen thus blocking its penetration into the cell, directly participate in the presentation of antigens to immunocompetent cells, transport antibacterial substances (interferons, lysozyme) to the zone of infection. In addition, macroglobulins take part in the apoptosis regulation in infected cells, utilization of the lysosomal enzymes of annihilated pathogens. The complexes of macroglobulins with some proteins are powerful inductors of antibody production. Further studies of the properties of these proteins will result in a better understanding of the nature of infectious process. The possibility of artificial formation of macroglobulin complexes with pathogen components or with substances possessing protective or anti-inflammatory properties opens prospects for using these proteins in the fields of vaccinology, gene therapy and molecular biology.     

Effect of alpha-ketoglutarate and its structural analogues on hysteretic properties of alpha-ketoglutarate dehydrogenase

The burst of product accumulation during the KGD reaction was investigated. It has been shown not to be the obligatory feature of catalysis, but appears when increasing the enzyme saturation by KG. Structural analogues of KG and the SH-group modification suppress the initial burst without preventing catalysis. The results obtained are in favour of the existence of the regulatory site for binding KG and its structural analogues essential for hysteretic properties of KGD.     

Metal dilution effects on the switching properties of CoFe Prussian blue analogues

Recent years have seen the discovery of unusual and fascinating electronic properties in Prussian blue analogues. Thus, some CoFe Prussian blue analogues exhibit a photomagnetic effect. Here, we present the first study of metal dilution effect on the switching properties in two different CoFe Prussian blue analogues. This investigation shows that metal dilution strongly depends on the stoichiometry of the compounds and the nature of the diluting agents. The switching properties can either be totally killed for low dilution rate or be persist at a CoFe pair scale.     

Conformational changes of alpha-macroglobulin and ovomacroglobulin from the green turtle (Chelonia mydas japonica)

Green turtle plasma alpha-macroglobulin and ovomacroglobulin underwent conformational changes when they were treated with proteinases or methylamine. Their conformational changes were studied by HPLC gel chromatography, circular dichroism, and electron microscopy. The Stokes radii of native green turtle alpha-macroglobulin and ovomacroglobulin were estimated to be 84.3 +/- 0.5 A, and 93.0 +/- 0.5 A, respectively, by means of an HPLC experiment. After reaction with methylamine or proteinases, the Stokes radius of alpha-macroglobulin changed to 83.0 +/- 0.5 A or 85.4 +/- 0.5 A, respectively, and that of ovomacroglobulin to 93.0 +/- 0.5 A or 87.1 +/- 0.5 A. The circular dichroic spectra of native alpha-macroglobulin and ovomacroglobulin exhibited a negative band at around 215 nm, indicating the presence of beta-structure. Reaction of the two macroglobulins with methylamine resulted in a slight decrease in the ellipticity and reaction with proteinases led to a slight increase. The electron micrographic images of native alpha-macroglobulin and ovomacroglobulin can be described as deformed rings for the former and rugby balls for the latter. A common characteristic feature of the two molecules was that the central parts of the molecules were only thinly occupied by subunit. After reaction of macroglobulins with proteinases, the void spaces became partially filled and their overall shape more rectangular. Methylamine treatment caused a structural change only in alpha-macroglobulin but not in ovomacroglobulin. The difference in the susceptibility of the macroglobulins to methylamine was taken as an indication of evolutional divergence of the two homologous proteins within the last 300 million years.     

Synthesis and evaluation of curcumin analogues as potential thioredoxin reductase inhibitors

Series of curcumin derivatives were synthesized; the inhibitory activities on thioredoxin reductase (TrxR) of all analogues were evaluated by DTNB assay in vitro. It is found that most of the analogues can inhibit TrxR in the low micromolar range; Structure-activity relationship analysis reveals that analogues with furan moiety have excellent inhibitory effect on TrxR in an irreversible manner, indicating that the furan moiety may serve as a possible pharmacophore during the interaction of curcumin analogues with TrxR. The effect of selected curcuminoids on growth of different TrxR overexpressed cancer cell lines was also investigated and discussed.     

Sterol-phospholipid interaction in model membranes: role of C5-C6 double bond in cholesterol

Several double-bond isomers of cholesterol where the normal C5-C6 double bond (delta 5) has been moved to different positions in the ring skeleton, i.e., delta 1, delta 4, delta 7, delta 8(9), delta 8(14), and delta 14, have been synthesized and incorporated in phosphotidylcholine vesicles. In addition, dienes like delta 5,7, delta 7,14, and delta 8,14 have also been studied. Many of these cholesterol analogues are intermediates in the sterol biosynthesis in different organisms. The incorporation studied indicated that more than 90% of the sterol was present in the vesicles. The effect of these cholesterol analogues was studied by glucose permeability, electron spin resonance, and fluorescence polarization spectroscopy. These studies indicated that delta 14-cholesten-3 beta-ol was most effective in restricting glucose permeability or in increasing the order parameter but was still not as effective as cholesterol. This was followed by delta 8(14)- and delta 8(9)-cholesten-3 beta-ol. The delta 1, delta 4, and delta 7 analogues and the dienols were relatively less effective in condensing the membrane. These studies indicate that the double bond at C5-C6 in cholesterol is most effective for optimal sterol-phospholipid interaction and may have formed the basis of the migration of the double bond from rings C and D in sterols to C5-C6 during the evolution of cholesterol.     

Substrate properties of C5-substituted pyrimidine 2'-deoxynucleoside 5'-triphosphates for thermostable DNA polymerases during PCR

In order to enhance a collection of modified deoxynucleoside triphosphates useful for in vitro selection or SELEX (systematic evolution of ligands by exponential enrichment) techniques, we designed and synthesized modified analogues of 2'-deoxyuridine triphosphate and 2'-deoxycytidine triphosphate bearing a flexible and hydrophilic 7-amino-2,5-dioxaheptyl linker at a C5 position. Both analogues were found to be substrates for thermostable DNA polymerases which belong to an evolutional family B during PCR.     

Colorimetric inorganic pyrophosphate assay using a double cycling enzymatic method

The biosynthesis of aminocoumarin antibiotics involves the action of amide synthetases which construct amide bonds between aminocoumarins and various acyl moieties. Libraries of aminocoumarin analogues have been generated by in vivo fermentation, via feeding known amide synthetase substrates into producing microbial strains. Critically, such feeding studies rely on the inherent or engineered substrate promiscuity of each amide synthetase. We have initiated a program of directed evolution in order to create mutant amide synthetases for the synthesis of new nonnatural amino coumarin analogues. We used the clorobiocin enzyme CloL as a model amide synthetase to design and validate a fluorimetric high-throughput screen, which can be used to report the activity of mutant amide synthetases toward a broad range of coumarin and acyl donor substrates. Our assay monitors the decrease in fluorescence of aminocoumarins on acylation. The utility of the assay was illustrated by screening a library of amide synthetase mutants created by error-prone PCR. The substrate specificity of an amide synthetase was also rapidly probed using this assay, affording several newly identified substrates. It is anticipated that this high-throughput screen will accelerate the creation of amide synthetase mutants with new specificities by directed evolution.     

Effects of chronic treatment of rats with "designer" amphetamines on brain regional monoamines.

(+)-Amphetamine and two structurally related analogues, 4-methoxyamphetamine and a recent "designer drug," 4-ethoxyamphetamine, were given to rats via subcutaneous osmotic minipumps for 1-14 days. Regional brain levels of the drugs as well as monoamine neurotransmitters and some of their major acidic metabolites were determined. Amphetamine produced depletions of dopamine in the striatum after at least 3 days of treatment but not in the nucleus accumbens of olfactory tubercle, even after 14 days of treatment. In contrast, the two ring-substituted amphetamine analogues increased levels of the monoamines and decreased levels of their acid metabolites. These data indicate that the two ring-substituted amphetamine analogues, at least one of which is a potent hallucinogen, have potent monoamine oxidase inhibition properties that are sustained during chronic treatment. Furthermore, these two compounds do not share amphetamine's regionally selective neurotoxic effects on dopamine-releasing terminals, even though brain and striatal drug levels are the same or higher than those of amphetamine.     

Rat alpha2 acute-phase macroglobulin. Isolation and physicochemical properties.

1. Rat alpha2 acute-phase macroglobulin was isolated from turpentine-injected rats by Sephadex G-200 chromatography and ion-exchange chromatography on DEAE-cellulose. This method, since it does not include (NH4)2SO4 treatment, allows the study of the physicochemical as well as the biological properties of the molecule. 2. The purity of the preparation was demonstrated by ultracentrifugation, polyacrylamide-gel electrophoresis, fused "rocket" immunoelectrophoresis as well as double immunodiffusion. 3. The rat alpha2 acute-phase macroglobulin was characterized in terms of its main physical and chemical properties. Its isoelctric point was determined by isoelectrofocusing to be 4.55; s020,w was 18.4S and E1%/1cm at 278 nm was 6.8. The mol.wt. was determined by light-scattering to be 770000. 4. The amino acid content was compared with that of rat alpha1 macroglobulin and was found very similar. The carbohydrate composition of alpha2 acute-phase macroglobulin was determined to be: hexose, 4.25%; glucosamine, 3.4%; sialic acid, 2%; fucose, 0.2%. From these results it was concluded that alpha2 acute-phase macroglobulin, although a typical acute-phase reactant, possesses the characteristic physicochemical properties of alpha macroglobulins.