Emergence and intensification of dairying in the Caucasus and Eurasian steppes.

Archaeological and archaeogenetic evidence points to the Pontic-Caspian steppe zone between the Caucasus and the Black Sea as the crucible from which the earliest steppe pastoralist societies arose and spread, ultimately influencing populations from Europe to Inner Asia. However, little is known about their economic foundations and the factors that may have contributed to their extensive mobility. Here, we investigate dietary proteins within the dental calculus proteomes of 45 individuals spanning the Neolithic to Greco-Roman periods in the Pontic-Caspian Steppe and neighbouring South Caucasus, Oka-Volga-Don and East Urals regions.

Ten millennia of hepatitis B virus evolution.

Hepatitis B virus (HBV) has been infecting humans for millennia and remains a global health problem, but its past diversity and dispersal routes are largely unknown. We generated HBV genomic data from 137 Eurasians and Native Americans dated between ~10,500 and ~400 years ago. We date the most recent common ancestor of all HBV lineages to between ~20,000 and 12,000 years ago, with the virus present in European and South American hunter-gatherers during the early Holocene.

Accessibility of tryptophan residues in immunoglobulin M as an index of its conformational changeability.

Demonstrated herein is the possibility of using the accessibility of tryptophan (Trp) residues in immunoglobulin M (IgM) upon modification with Koshland reagent (2-hydroxy-5-nitrobenzyl bromide) as an index of the conformational changeability of IgM. Of fourteen Trp's in the native IgM (per HL-region) only one appeared to be most accessible, evidently Trp312 in the mu-chain. Irreversible acidic and thermal conformational transitions in IgM increase the number of accessible Trp's approximately two-fold.

[Accessibility of tryptophan residues in immunoglobulin M molecule as an indicator of its conformational variability].

The accessibility of tryptophan residues in immunoglobulin M to modification with the Koshland reagent (2-hydroxy-5-nitrobenzyl bromide) was used as an indicator of its conformational variability. Of 14 tryptophan residues (per HL-fragment) in the native IgM, only one (presumably Trp312 in the mu-chain) was the most accessible. Irreversible acid- or temperature-induced conformational changes of IgM increased almost 2-fold the number of accessible tryptophan residues.

[Various research results on the role of carbohydrate groups in macroimmunoglobulins].

Evidence on the role of carbohydrates in the structure and function of macroimmunoglobulin (IgM) was obtained. The principal functions are the increase of hydrophilicity and preservation of a definite conformation of the protein molecule which, in its turn, is necessary for the implementation of its biological function. The protection of tryptophan residues at the molecule surface against the contacts with the surrounding water is conditioned by the above properties.

[Changes in the immunoglobulin M conformation in media with different degrees of acidity].

The pH-dependent conformational changes in immunoglobulin M were studied by differential spectrophotometry. It was found that the state of chromophores (tryptophan and tyrosine) which reflects conformational changes of the structure alters stepwise in the course of acidification. The native structure is not restored by neutralization.

[Isolation of thyroglobulin from the bovine thyroid free of endogenous proteolytic activity].

Thyroglobulin was isolated from the cattle thyroid gland by chromatography on Sephadex G-200 and Sepharose 4B. It was found homogeneous according to disc electrophoresis (pH 8.6) and analytical ultracentrifugation.

[Modification of tryptophan residues in immunoglobulin M by 2-hydroxy-5-nitrobenzyl bromide].

The modification of tryptophan residues in monoclonal immunoglobulin M (IgM) by 2-hydroxy-5-nitrobenzyl bromide (RK) was studied at pH 2.0-2.85 and 7.

[Study of conformational changes in immunoglobulin M using the method of differential spectroscopy].

Using differential and solvent-perturbation spectrophotometry, the nature of conformational changes in immunoglobulin M (IgM) in different regimens was investigated. The quantities of tryptophan and tyrosine chromophores exposed on the surface of the molecule and screened, were evaluated. The changes in pH (7.

[The role of carbohydrate groups in IgM. VIII. The effect of treatment of IgM with acids on the subsequent action of glycosidases and endogenous proteinases].

Exposure of IgM to acidic medium (pH approximately 3, 30 min, at 20 degrees) and subsequent returning to neutral conditions leads to irreversible changes in the state of the molecule. This results in the loss of IgM accessibility for the action of glycosidases and, at the same time, makes it more susceptible to the action of proteinases. Both effects are thought to be due to an irreversible conformational rearrangement of IgM in acidic medium.

[The role of thyroglobulin carbohydrates in its hormone-liberating function. Proteolysis of deglycosylated thyroglobulin].

The proteolysis of thyroglobulin was performed after partial cleavage of its carbohydrate moiety. It was demonstrated that enzymatic removal of some thyroglobulin sialic acids results in increasing its resistance to proteolysis. Apparently, sialic acids are essential for maintaining an optimal thyroglobulin conformation for the action of proteases at hormonal biosynthesis from the reserve form.

[Immunogenicity and thymus-dependence of the polymerized alpha-toxoid of Clostridium perfringens].

Polymeric alpha-toxoid with a molecular weight of 450 000--600 000 was obtained by condensation of alpha-toxoid of Cl. perfringens, type A, with glutaric aldehyde. Experiments on guinea pigs showed that in the adsorbed preparations the immunogenic properties of both monomeric and polymeric alpha-toxoids are practically identical.

[Isolation and characterization of beta-D-galactosidase from gastric juice].

A method for beta-D-galactosidase isolation from cattle gastric juice has been developed. Gastric juice mucus was removed by and addition of equimolar amounts of Na2HPO4 and CaCl2. The removal of proteases and other proteins was achieved by the treatment with resins KB-51X2 and AN-22.

[Anionic center of porcine pancreatic phospholipase A2].

The interaction between porcine pancreatic phospholipase A2 and low-molecular fragments of its substrate -- lecithine was studied using gel-diffusion of the enzyme in lecithin-agarose plates. When the inhibitor was added, a decrease in the magnitude of cleared areas (l/l0) around the depots filled with enzyme solution was observed. A marked decrease in l/l0 in the presence of alpha- and beta-glycerophosphates supported the statement that the cathionic center is a part of the enzyme active site SII.

[Selectivity of lysozyme oxidation by singlet oxygen].

Peptide analysis of tryptic hydrolysates of two lysozyme forms derived from oxidation of lysozyme with singlet oxygen shows that Trp-62, located at the active site, is destroyed. This is confirmed by the protective effect of the substrate (chitin), whose presense practically prevents the oxidation. A possibility of oxidating different tryptophan residues is discussed from the view-point of their availability to the reagent.

[Study of the composition of killer whale meat as a source of balanced proteins].

Investigations have shown the proteins of the Orca meat to consist largely of complete water-salt and alkaline-soluble fractions and of an insignificant amount of connective-tissue proteins. The proteins of the Orca meat contain all the amino acids, including essential ones. The lysine and histidine content there in is 1.

[Nature of tryptophan photooxidation products in lysozyme in the presence of methylene blue].

One out of six trytophan residues in two lysozyme modification, obtained under lysozyme photooxidation in the presence of methylene blue, is found to be oxidized to N'-formylkinurenine (in one modification) and to kinurenine (in the other modification). The transition of one modification into another via detaching of N'-formyl group by soft acid hydrolysis has shown that one and the same tryptophan residue is oxidized in both products, Possible mechanism of tryptophan oxidation to the products mentioned is discu-sed on the basis of the hypothesis on signlet mechanism of lysozyme photooxidation in the presence of methylene blue.