Comparative study of monoclonal immunoglobulin M and rheumatoid immunoglobulin M by differential scanning microcalorimetry.

Thermal denaturation of monoclonal immunoglobulin M (IgM) and rheumatoid immunoglobulin M (IgM-RF) and their Fab- and (Fc)5-fragments was studied by differential scanning microcalorimetry. The melting of IgM-RF started at a higher temperature than that of IgM and the maximum temperature of its main asymmetric peak of heat absorption was higher by 4 degrees C. At equal values of enthalpy, the thermal denaturation of IgM-RF and IgM consisted of four and five individual transitions, respectively, between pairs of states. The comparison of thermal denaturation parameters of Fab- and (Fc)5-fragments of IgM-RF and IgM showed a thermodynamic similarity of (Fc)5-fragments of both proteins, while their Fab-fragments differed in the interaction between VL-CL and VH-CH domains.

Preparation of cyclic 2',3'-monophosphates of oligoadenylates (A2'p)nA > p and A3'p(A2'p)n-1A > p.

The action of the guanylyl-preferring RNase from Bacillus intermedius (binase) on a mixture of oligoadenylates with randomly distributed 2'-5' and 3'-5' internucleotide bonds [(A2'/3'p)n] under conditions sufficient for complete hydrolysis of poly(A) results in a mixture containing a single circular oligoadenylate and two series of linear oligoadenylates ending in cyclic 2',3'-phosphate. Individual compounds formed upon digestion of (A2'/3'p)n with binase have been isolated. Their structure was determined on the basis of their chemical and enzymatic conversions and confirmed by 1H-, 13C- and 31P-NMR spectra. According to these data, the circular triadenylate contains one 2'-5' and two 3'-5' internucleotide bonds, linear oligoadenylates of one series contain exclusively 2'-5' internucleotide bonds [(A2'p)nA > p], while each compound of the other series contains a single 3'-5' internucleotide bond connecting the 5'-ultimate nucleotide residue with the penultimate one [A3'p(A2'p)n-1A > p]. The incubation of compounds of the former series A3' p(A2'p)n > p at pH 1.0 and the subsequent action of phosphatase results in successive formation of compounds of two other new series: A3'p(A2'p)nA2'(3')p and A3'p(A2'p)nA.

[Characteristics of the effect of egg lysozyme on micrococci and staphylococci]. / Osobennosti deistviia iaichnogo lizotsima na mikrokokki i stafilokokki.

The nature of the optical density of suspensions of Staph. aureus and M. luteus cells at various concentrations of chicken egg albumin lysozyme and two products of its chemical transformation was studied comparatively. The experiments were performed in 1/15 M Na-phosphate buffer at pH 6.2 and a temperature of 20-22 degrees C. It was shown that the decrease in the optical density of the suspensions observed at relatively low concentrations of lysozyme, i.e. 0.032-0.064 mg/ml, was due to lysis of both microbial species. The increase in the optical density of the suspensions at higher (0.5-2.0 mg/ml) concentrations of lysozyme was connected with formation of insoluble aggregates of an electrostatic character. Lysozyme in such aggregates is the positively charged component and the microbial cell material is the negatively charged component. When M. luteus strains are sensitive to lysozyme, the aggregates are formed from the cell fragments or lysis acid products. When Staph, aureus strains have higher resistance levels, the aggregates are formed from both the lysis products and the intact live cells which is of special interest.

[Action of egg lysozyme on representatives of the family Micrococcaceae. The action on staphylococci]. / Deistvie iaichnogo lizotzima na predstavitelei semeistva Micrococcaceae. Deistvie na stafilokokki.

The results of the study on the effect of various concentrations of lysozyme on staphylococci of three species, i.e. Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus saprophyticus are presented. The study was performed with the use of the turbidimetric method. It was found that all the staphylococci had a common tendency for changing the optic density (OD) of the suspensions under the effect of lysozyme which was different from that in Micrococcus luteus. However, the dynamics of decreasing the OD in Staph. saprophyticus was characterized by some properties which provided a supposition that the structures of the cell walls in Staph. aureus and Staph. epidermidis were close, while the cell walls in Staph. saprophyticus had some unknown characteristics.

[Action of egg lysozyme on representatives of the family Micrococcaceae. Its action on Micrococcus]. / Deistvie iaichnogo lizozima na predstavitelei semeistva Micrococcaceae. Deistvie na mikrokokki.

The results of the study of the effect of various concentrations of egg lysozyme on M. luteus and M. varians using 2 methods, i.e. serial dilutions in agar and turbidimetric are presented. It was found that the MIC of lysozyme for M. luteus ranged within wide limits, from less than 0.0003 to 1 mg/ml. M. varians was stable to lysozyme. The MIC for all the strains was 8 mg/ml. The turbidimetric method provided determination of general regularities in changes of the optical density in all the strains of M. luteus under the effect of various concentrations of lysozyme. On the basis of these data it was possible to consider the method as the most deep means for determining the intraspecies similarities in the surface structures of Micrococcus as compared to the method of serial dilutions in agar. The dynamics of the changes in the optical density of the M. luteus suspension markedly differed from that of M. varians.

[Preparation and characteristics of carboxymethylated lysozyme derivatives]. / Poluchenie i kharakteristika karboksimetilproizvodnykh lizotsima.

Hen egg-white lysozyme (EC 3.2.1.17) was carboxymethylated with iodoacetic acid and the individual products of various degree of modification were isolated by column chromatography on Amberlite CG-50. Peptide mapping of the products obtained reveals that His-15, Lys-1, -33, -96 (or -97) residues are blocked; the Lys-13 and -116 residues are unmodified. Salt activation of the carboxymethylated derivatives is facilitated with the increase of the number of modified groups; this fact is consistent with the increased lytic activity and affinity to substrate of the derivatives at lowered ionic strength.

[Isolation and some properties of mink lysozyme]. / Vydelenie i nekotorye s voistva lizotsima norka.

Lysozyme (EC 3.2.1.17) from spleen, kidney and liver of mink was isolated by affinity chromatography on deaminated chitin. The histidine content of mink lysozyme is unusually high and comprises 7 residues per mole of the protein. The acidic and basic amino acid residues are present in the mink lysozyme in nearly equal amounts (20-22); in this respect, the degree of amidation of the side chain carboxylic groups is relatively low (8-10). The lysozyme preparations obtained are found to contain an unknown, tightly bound component, absorbing at 400-420 nm.

[The role of the tryptophan-62 residue in the structure and function of lysozyme]. / O roli ostatka triptofana-62 v strukture i funktsii lizotsima

The thermostability and thermodinamics of formation of the enzyme-substrate complex of two oxidation products of chicken egg lysozyme with the tryptophane-62 residue modified to N'-formylkinurenine (with 2.5% activity) and kinurenine (with 27.5% activity) have been studied. In thermostability and pH effect on the substrate binding the lysozyme oxidation products do not differ from native lysozyme. The data obtained and thermodynamical characteristics of the enzyme-substrate complex formation suggest that the chemical nature of the 62 residue does not significantly affect the conformational properties of lysozyme, however, having a strongly pronounced effect on the binding of substrate and hence the total enzyme activity.

[Main causes of death of patients with diabetes mellitus]. / Vyiavlenie osnovnykh prichin smerti bol'nykh sakharnym diabetom

Among the causes of death in the patients with diabetes mellitus in Ukraine there prevailed cardiovascular disease (73.1 +/- 0.19%); malignant neoplasms ranked second (12.1 +/- 1.2%); tuberculosis constituted 1.6 +/- 1.2%, and all the rest of the diseases - 13.1 +/- +/- 1.2%, including coma - 0.5%. The frequency of death, particularly from cardiovascular diseases, is influenced by the patients' age, the severity and the duration of metabolic disturbances. The methods of treatment, particularly the saccharolytic sulphanilamide preparations, produce no effect on the death incidence.

[Production of a lysozyme-like enzyme by various representatives of the genus Staphylococcus]. / Produktsiia lizotsimpodobnogo fermenta razlichnymi predstaviteliami roda Staphylococcus

On the basis of studying 855 strains of various staphylococci it was shown that production of a lysozyme-like enzyme (LLE) failed to serve as a characteristic sign for all the representatives of Staphylococcus genus. It was mostly observed in S. aureus (in 85% of the strains). In nonpathogenic strains of S. epidermidis LLE could not be revealed either by the dish or by affine chromatography on chitin; among S. epidermidis, isolated from the patients there were cultures which did or did not form the LLE. Cultures occupying an intermediate position (coagulase-negative or mannite-negative) formed the LLE in 66.9% of cases. It was shown that the virulence and the general biological activity of the lysozyme-positive intermediate strains were higher than in the lysozyme-negative ones.