Valueva Tatyana A

Bio: Valueva Tatyana A is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Proteolytic enzymes & Chymotrypsin. The author has an hindex of 15, co-authored 58 publications receiving 827 citations.

Role of inhibitors of proteolytic enzymes in plant defense against phytopathogenic microorganisms.

Abstract: This review analyzes the literature on various mechanisms of proteolytic enzyme inhibitors involved in plant defense against attack by phytopathogenic microorganisms. The action of proteinase inhibitors from plants upon the enzymes from pathogenic microorganisms and viruses is reviewed. Considerable attention is given to the induction of proteinase inhibitors in plants in response to the invasion of pathogens. Some aspects of application of proteinase inhibitors in biotechnology for production of transgenic plants with enhanced resistance to diseases are discussed.

[Proteinase inhibitors and their function in plants: a review].

Abstract: The spread, classification, and properties of plant proteins capable of inhibiting proteinases have been reviewed. Data from the literature on the likely physiological functions of these inhibitors in plants are analyzed.

Protein-containing polymer composition for oral administration

Abstract: A therapeutic-containing composition adapted for the oral administration of a biologically active material which comprises a water insoluble but water swellable polymer chemically modified with an enzyme inhibitor containing a chemical functionality which has an interactive affinity for target receptors located on the transport barrier walls of the digestive tract of the intended recipient, and at least one therapeutic of low oral bioavailability.

[Proteinase inhibitors in plant biotechnology: a review].

Abstract: Possible utilities for natural inhibitors of proteolytic enzymes in plant biotechnology have been reviewed. Among the potential areas of use of the inhibitors are (1) construction of transgenic plants with increased resistance to insects and other pests and (2) development of procedures for biosynthesis of recombinant proteins. In the latter case, the inhibitors will serve to prevent the protein degradation by proteinases.

Evolutionary families of peptidase inhibitors.

Abstract: The proteins that inhibit peptidases are of great importance in medicine and biotechnology, but there has never been a comprehensive system of classification for them. Some of the terminology currently in use is potentially confusing. In the hope of facilitating the exchange, storage and retrieval of information about this important group of proteins, we now describe a system wherein the inhibitor units of the peptidase inhibitors are assigned to 48 families on the basis of similarities detectable at the level of amino acid sequence. Then, on the basis of three-dimensional structures, 31 of the families are assigned to 26 clans. A simple system of nomenclature is introduced for reference to each clan, family and inhibitor. We briefly discuss the specificities and mechanisms of the interactions of the inhibitors in the various families with their target enzymes. The system of families and clans of inhibitors described has been implemented in the MEROPS peptidase database (http://merops.sanger.ac.uk/), and this will provide a mechanism for updating it as new information becomes available.

Plant alpha-amylase inhibitors and their interaction with insect alpha-amylases.

Abstract: Insect pests and pathogens (fungi, bacteria and viruses) are responsible for severe crop losses. Insects feed directly on the plant tissues, while the pathogens lead to damage or death of the plant. Plants have evolved a certain degree of resistance through the production of defence compounds, which may be aproteic, e.g. antibiotics, alkaloids, terpenes, cyanogenic glucosides or proteic, e.g. chitinases, β-1,3-glucanases, lectins, arcelins, vicilins, systemins and enzyme inhibitors. The enzyme inhibitors impede digestion through their action on insect gut digestive α-amylases and proteinases, which play a key role in the digestion of plant starch and proteins. The natural defences of crop plants may be improved through the use of transgenic technology. Current research in the area focuses particularly on weevils as these are highly dependent on starch for their energy supply. Six different α-amylase inhibitor classes, lectin-like, knottin-like, cereal-type, Kunitz-like, γ-purothionin-like and thaumatin-like could be used in pest control. These classes of inhibitors show remarkable structural variety leading to different modes of inhibition and different specificity profiles against diverse α-amylases. Specificity of inhibition is an important issue as the introduced inhibitor must not adversely affect the plant's own α-amylases, nor the nutritional value of the crop. Of particular interest are some bifunctional inhibitors with additional favourable properties, such as proteinase inhibitory activity or chitinase activity. The area has benefited from the recent determination of many structures of α-amylases, inhibitors and complexes. These structures highlight the remarkable variety in structural modes of α-amylase inhibition. The continuing discovery of new classes of α-amylase inhibitor ensures that exciting discoveries remain to be made. In this review, we summarize existing knowledge of insect α-amylases, plant α-amylase inhibitors and their interaction. Positive results recently obtained for transgenic plants and future prospects in the area are reviewed.

In Posidonia oceanica cadmium induces changes in DNA methylation and chromatin patterning

Abstract: In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short- (6 h) and long- (2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.

Hydrogels and drug delivery

Abstract: Recent developments include the use of water-swollen, crosslinked biomedical polymers as carriers for the delivery of drugs, peptides and proteins, as targeting agents for site-specific delivery, or as components for preparation of protein or enzyme conjugates. The network structure and the thermodynamic nature of the components of these networks play a key role in their diffusional behavior, molecular mesh size changes (especially in environmentally responsive hydrogels), and the associated molecular stability of the incorporated bioactive agents.