RESUMEN

BACKGROUND: An extensive study of the folding and stability of proteins and their complexes has revealed a number of problems and questions that need to be answered. One of them is the effect of chaperones on the process of fibrillation of various proteins and peptides. METHODS: We studied the effect of molecular chaperones, such as GroEL and α-crystallin, on the fibrillogenesis of the Aß(1-42) peptide using electron microscopy and surface plasmon resonance. RESULTS: Recombinant GroEL and Aß(1-42) were isolated and purified. It was shown that the assembly of GroEL occurs without the addition of magnesium and potassium ions, as is commonly believed. According to the electron microscopy results, GroEL insignificantly affects the fibrillogenesis of the Aß(1-42) peptide, while α-crystallin prevents the elongation of the Aß(1-42) peptide fibrils. We have demonstrated that GroEL interacts nonspecifically with Aß(1-42), while α-crystallin does not interact with Aß(1-42) at all using surface plasmon resonance. CONCLUSION: The data obtained will help us understand the process of amyloid formation and the effect of various components on it.

Asunto(s)

Amiloidosis , alfa-Cristalinas , Amiloide/química , Péptidos beta-Amiloides/metabolismo , Proteínas Amiloidogénicas , Humanos , Chaperonas Moleculares/genética , Fragmentos de Péptidos/química

RESUMEN

Functionally important multidomain bacterial protein bS1 is the largest ribosomal protein of subunit 30S. It interacts with both mRNA and proteins and is prone to aggregation, although this process has not been studied in detail. Here, we obtained bacterial strains overproducing ribosomal bS1 protein from Thermus thermophilus and its stable fragment bS1(49) and purified these proteins. Using fluorescence spectroscopy, dynamic light scattering, and high-performance liquid chromatography combined with mass spectrometric analysis of products of protein limited proteolysis, we demonstrated that disordered regions at the N- and C-termini of bS1 can play a key role in the aggregation of this protein. The truncated fragment bS1(49) was less prone to aggregation compared to the full-size bS1. The revealed properties of the studied proteins can be used to obtain protein crystals for elucidating the structure of the bS1 stable fragment.

Asunto(s)

Proteínas Bacterianas/metabolismo , Proteínas Ribosómicas/metabolismo , Thermus thermophilus/metabolismo , Dicroismo Circular , Iones , Luz , Espectrometría de Masas , Unión Proteica , Dominios Proteicos , Estructura Secundaria de Proteína , Proteolisis , ARN Bacteriano/metabolismo , ARN Mensajero/metabolismo , Dispersión de Radiación , Espectrometría de Fluorescencia , Temperatura

RESUMEN

Studies of the process of amyloid formation by Aß peptide have been topical due to the critical role of this peptide in the pathogenesis of Alzheimer's disease. Many articles devoted to this process are available in the literature; however, none of them gives a detailed description of the mechanism of the process of generation of amyloids. Moreover, there are no reliable data on the influence of modified forms of Aß peptide on its amyloid formation. To appreciate the role of Aß aggregation in the pathogenesis of Alzheimer's disease and to develop a strategy for its treatment, it is necessary to have a well-defined description of the molecular mechanism underlying the formation of amyloids as well as the contribution of each intermediate to this process. We are convinced that a combined analysis of theoretical and experimental methods is a way for understanding molecular mechanisms of numerous diseases. Based on our experimental data and molecular modeling, we have constructed a general model of the process of amyloid formation by Aß peptide. Using the data described in our previous publications, we propose a model of amyloid formation by this peptide that differs from the generally accepted model. Our model can be applied to other proteins and peptides as well. According to this model, the main building unit for the formation of amyloid fibrils is a ring-like oligomer. Upon interaction with each other, ring-like oligomers form long fibrils of different morphology. This mechanism of generation of amyloid fibrils may be common for other proteins and peptides.

Asunto(s)

Péptidos beta-Amiloides/química , Proteínas Amiloidogénicas/síntesis química , Proteínas Amiloidogénicas/química , Animales , Humanos

RESUMEN

We analyzed the structural properties of the peptide hormone insulin and described the mechanism of its physiological action, as well as effects of insulin in type 1 and 2 diabetes. Recently published data on the development of novel insulin preparations based on combining molecular design and genetic engineering approaches are presented. New strategies for creation of long-acting insulin analogs, the mechanisms of functioning of these analogs and their structure are discussed. Side effects of insulin preparations are described, including amyloidogenesis and possible mitogenic effect. The pathways for development of novel insulin analogs are outlined with regard to the current requirements for therapeutic preparations due to the wider occurrence of diabetes of both types.

Asunto(s)

Insulina/análisis , Animales , Humanos , Insulina/metabolismo

RESUMEN

As has been recently shown, the toxicity of protein aggregates is determined by their structure. Therefore, special attention has been focused on the search for factors that specify the structural features of formed amyloid fibrils. The effect of amino acid substitutions in apomyoglobin on the structural characteristics of its amyloid aggregates has been analyzed. The morphology and secondary structure of amyloids of the wild-type protein and its mutant variants Val10Ala, Val10Phe, and Trp14Phe have been compared, and the regions involved in intermolecular interactions in fibrils have been determined using limited proteolysis and mass spectrometry. No considerable differences have been found in the morphology (shape, length, or diameter) or the content (percentage) of the cross-ß structure of apomyoglobin amyloids and its mutant variants. Amyloid cores of wild-type apomyoglobin and variants with Val10Phe and Trp14Phe substitutions have been formed by different regions of the polypeptide chain. The case study of apomyoglobin demonstrates that the location of amyloidogenic regions in the polypeptide chain of wild-type protein and its mutant forms can differ. Thus, possible structural changes in amyloids resulting from amino acid substitutions should be taken into account when studying phenotype aggregation.

Asunto(s)

Amiloide/química , Apoproteínas/química , Mioglobina/química , Sustitución de Aminoácidos , Animales , Apoproteínas/genética , Mioglobina/genética , Estructura Secundaria de Proteína

RESUMEN

The products of the reassembly reaction of tetradecameric two-ring quaternary structure of GroEL chaperonin under the pressure of its heptameric co-chaperonin GroES have been visualized by electron microscopy. It has been shown that one-ring heptameric oligomers of GroEL have been formed at the beginning (after ~5 min) of the reaction, while at the final stage of the reaction (after ~70 min), both one-ring heptamers in complex with one GroES and two-rings tetradecamers in complexes with one (asymmetrical complex) or two (symmetrical complex) GroES heptamers are present. The relationship between the data of light scattering, native electrophoresis, and electron microscopy obtained earlier has been discussed.

Asunto(s)

Chaperonina 10/química , Chaperonina 60/química , Proteínas de Escherichia coli/química , Escherichia coli/química , Chaperonina 10/ultraestructura , Chaperonina 60/ultraestructura , Proteínas de Escherichia coli/ultraestructura , Microscopía Electrónica , Unión Proteica , Pliegue de Proteína

RESUMEN

TA characteristic feature of amyloid structures is polymorphism. The study of amyloid structures and their formation process was carried out for synthetic and recombinant Ab(1-40) and Ab(1-42) peptide preparations. In the study of these peptides, we recognized fibrils of different morphologies. We observed fibrillar formations in the form of single fibrils, ribbons, bundles, bunches, and clusters. Polymorphism of fibrils was observed not only when the environmental conditions changed, but under the same conditions and this was a common characteristics of all amyloid formations. Fibrils of Ab(1-40) peptides tended to form aggregates of fibrils in the form of ribbons, while Ab(1-42) peptide under the same conditions polymerized in the form of rough fibrils of different diameters and tends to branch. We assume that the formation of fibrils of Ab(1-40) and Ab(1-42) peptides occurs according to a simplified scheme: a destabilized monomer ® a ring oligomer ® a mature fibril consisting of ring oligomers. Proceeding from the proposition that the ring oligomer is the main building block of amyloid fibril (similar to the cell in the body), it is easy to explain fibril polymorphism, as well as fragmentation of mature fibrils under various external influences, branching and irregularity of diameter (surface roughness) of fibrils. One aspect of the study of amyloidogenesis is the determination of the regions of the protein chain forming the core of the amyloid fibril. We theoretically predicted amyloidogenic regions for two isoforms of Ab peptides capable of forming an amyloid structure: 16-21 and 32-36 residues. Using the method of tandem mass spectrometry, these regions were determined experimentally. It was shown that the regions of Ab(1-40) peptide from 16 to 22 and from 28 to 40 residues were resistant to the action of proteases, i.e. its formed the core of the amyloid fibril. For Ab(1-42) peptide the whole sequence is not available for the action of proteases, which indicates a different way of associating ring oligomers in the formation of fibrils. Based on electron microscopy and mass spectrometry data we proposed a molecular model of the fibril formed by Ab(1-40) and Ab(1-42) peptides.

Asunto(s)

Amiloide/metabolismo , Amiloidosis , Secuencia de Aminoácidos , Péptidos beta-Amiloides , Humanos , Modelos Moleculares , Fragmentos de Péptidos , Péptidos

RESUMEN

During its life cycle, a cell can be subjected to various external negative effects. Many proteins provide cell protection, including small heat shock proteins (sHsp) that have chaperone-like activity. These proteins have several important functions involving prevention of apoptosis and retention of cytoskeletal integrity; also, sHsp take part in the recovery of enzyme activity. The action mechanism of sHsp is based on the binding of hydrophobic regions exposed to the surface of a molten globule. α-Crystallins presented in chordate cells as two αA- and αB-isoforms are the most studied small heat shock proteins. In this review, we describe the main functions of α-crystallins, features of their secondary and tertiary structures, and examples of their partners in protein-protein interactions.

Asunto(s)

Proteínas de Choque Térmico/química , Cadena A de alfa-Cristalina/química , Cadena B de alfa-Cristalina/química , Animales , Apoptosis/fisiología , Citoesqueleto/química , Citoesqueleto/metabolismo , Proteínas de Choque Térmico/metabolismo , Humanos , Dominios Proteicos , Estructura Secundaria de Proteína , Relación Estructura-Actividad , Cadena A de alfa-Cristalina/metabolismo , Cadena B de alfa-Cristalina/metabolismo

RESUMEN

A method for the synthesis and high purification of fragments of Aß(1-42) peptide has been elaborated. We have synthesized the amyloidogenic fragment Aß(16-25) predicted by us and studied the process of its aggregation by electron microscopy and X-ray analysis. Electron microscopy images show that the peptide forms a film, which is not characteristic of amyloid fibrils. At the same time, according to the X-ray diffraction data, its preparations display the presence of two main reflections (4.6-4.8 and 8-12 Å) characteristic of cross-ß structure of amyloid fibrils. Thus, the fragment Aß(16-25) that we predicted is a promising object not only for studying the process of polymerization of the peptides/proteins, but also for using it as a nanomaterial to study a number of biological processes.

Asunto(s)

Péptidos beta-Amiloides/metabolismo , Nanoestructuras/química , Amiloide/química , Amiloide/metabolismo , Cristalografía por Rayos X , Microscopía Electrónica , Estructura Secundaria de Proteína , Espectrometría de Masa por Ionización de Electrospray

RESUMEN

The studies of amyloid structures and the process of their formation are important problems of biophysics. One of the aspects of such studies is to determine the amyloidogenic regions of a protein chain that form the core of an amyloid fibril. We have theoretically predicted the amyloidogenic regions of the Aß(1-40) peptide capable of forming an amyloid structure. These regions are from 16 to 21 and from 32 to 36 amino acid residues. In this work, we have attempted to identify these sites experimentally by the method of tandem mass spectrometry. As a result, we show that regions of the Aß(1-40) peptide from 16 to 22 and from 28 to 40 amino acid residues are resistant to proteases, i.e. they are included in the core of amyloid fibrils. Our results correlate with the results of the theoretical prediction.

Asunto(s)

Péptidos beta-Amiloides/metabolismo , Amiloide/metabolismo , Fragmentos de Péptidos/metabolismo , Secuencia de Aminoácidos , Péptidos beta-Amiloides/síntesis química , Péptidos beta-Amiloides/química , Cromatografía Líquida de Alta Presión , Cristalografía por Rayos X , Microscopía Electrónica , Resonancia Magnética Nuclear Biomolecular , Fragmentos de Péptidos/síntesis química , Fragmentos de Péptidos/química , Conformación Proteica , Proteolisis , Espectrometría de Masa por Ionización de Electrospray

RESUMEN

The aim of this research was to design a method of immobilization of high-purity human butyrylcholinesterase on the surface of gold nanoparticles preserving the activity of the enzyme. In order to achieve this aim, the method of fractionation and purification of human butyrylcholinesterase from plasma was modified. The synthesis of 15-nm gold nanoparticles was carried out by citrated method. A method of conjugation of the high-purity butyrylcholinesterase with gold nanoparticles was developed. It was found that the Immobilization of butyrylcholinesterase on the surface of gold nanoparticles resulted in a significant (to 23%) increase in the specific activity of the enzyme.

Asunto(s)

Butirilcolinesterasa , Compuestos de Oro/síntesis química , Nanopartículas del Metal , Butirilcolinesterasa/química , Butirilcolinesterasa/aislamiento & purificación , Estabilidad de Enzimas , Compuestos de Oro/química , Humanos , Concentración de Iones de Hidrógeno , Nanopartículas del Metal/química , Tamaño de la Partícula

RESUMEN

We have developed a highly efficient method for purification of the recombinant product Aß(1-40) peptide. The concentration dependence of amyloid formation by recombinant Aß(1-40) peptide was studied using fluorescence spectroscopy and electron microscopy. We found that the process of amyloid formation is preceded by lag time, which indicates that the process is nucleation-dependent. Further exponential growth of amyloid fibrils is followed by branching scenarios. Based on the experimental data on the concentration dependence, the sizes of the folding nuclei of fibrils were calculated. It turned out that the size of the primary nucleus is one "monomer" and the size of the secondary nucleus is zero. This means that the nucleus for new aggregates can be a surface of the fibrils themselves. Using electron microscopy, we have demonstrated that fibrils of these peptides are formed by the association of rounded ring structures.

Asunto(s)

Péptidos beta-Amiloides/metabolismo , Amiloide/metabolismo , Fragmentos de Péptidos/metabolismo , Amiloide/química , Péptidos beta-Amiloides/química , Péptidos beta-Amiloides/genética , Cinética , Microscopía Electrónica , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Espectrometría de Fluorescencia , Espectrometría de Masa por Ionización de Electrospray

RESUMEN

Bacterial Hfq proteins are structural homologs of archaeal and eukaryotic Sm/Lsm proteins, which are characterized by a 5-stranded ß-sheet and an N-terminal α-helix. Previously, it was shown that archaeal Lsm proteins (SmAP) could produce long fibrils spontaneously, in contrast to the Hfq from Escherichia coli that could form similar fibrils only after special treatment. The organization of these fibrils is significantly different, but the reason for the dissimilarity has not been found. In the present work, we studied the process of fibril formation by bacterial protein Hfq from Pseudomonas aeruginosa and archaeal protein SmAP from Methanococcus jannaschii. Both proteins have high homology with E. coli Hfq. We found that Hfq from P. aeruginosa could form fibrils after substitutions in the conserved Sm2 motif only. SmAP from M. jannaschii, like other archaeal Lsm proteins, form fibrils spontaneously. Despite differences in the fibril formation conditions, the architecture of both was similar to that described for E. coli Hfq. Therefore, universal nature of fibril architecture formed by Hfq proteins is suggested.

Asunto(s)

Proteínas Arqueales/química , Proteína de Factor 1 del Huésped/química , Secuencia de Aminoácidos , Proteínas Arqueales/metabolismo , Proteínas Arqueales/ultraestructura , Proteína de Factor 1 del Huésped/metabolismo , Proteína de Factor 1 del Huésped/ultraestructura , Methanocaldococcus , Datos de Secuencia Molecular , Conformación Proteica , Pseudomonas aeruginosa

RESUMEN

In this review we analyze the main works on amyloid formation of insulin. There are many environmental factors affecting the formation of insulin amyloid fibrils (and other amyloidogenic proteins) such as: protein concentration, pH, ionic strength of solution, medium composition (anions, cations), presence of denaturants (urea, guanidine chloride) or stabilizers (saccharose), temperature regime, agitation. Since polymorphism is potentially crucial for human diseases and may underlie the natural variability of some amyloid diseases, in this review we focus attention on polymorphism that is an important biophysical difference between native protein folding suggesting correspondence between the amino acid sequence and unique folding state, and formation of amyloid fibrils, when the same amino acid sequence can form amyloid fibrils of different morphology. At present, according to the literature data, we can choose three ways of polymerization of insulin molecules depending on the nucleus size. The first suggests that fibrillogenesis can occur through assembly of insulin monomers. The second suggests that precursors of fibrils are dimers, and the third assumes that precursors of fibrils are oligomers. Additional experimental works and new methods of investigation and assessment of results are needed to clarify the general picture of insulin amyloid formation.

Asunto(s)

Amiloide/metabolismo , Insulina/metabolismo , Amiloide/química , Animales , Humanos , Insulina/química , Insulina/genética , Conformación Proteica , Pliegue de Proteína , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/genética

RESUMEN

This review is devoted to substantiation of new characteristics for classification of living organisms. The novel view of a role of flexible regions in protein functioning and evolution is suggested. It is based on the newly revealed correlation between the number of loops in elongation factors and the complexity of organisms. This correlation allowed us to formulate a hypothesis of evolution of this protein family. In addition, the study of the ribosomal protein S1 family made it possible to consider the number of structural domains as a reliable indicator of a microorganism's affiliation with a particular division and to judge about "direction" of their evolution. The findings allow us to consider the loops and repeats in these proteins as unique imprints of molecular evolution.

Asunto(s)

Bacterias/genética , Eucariontes/genética , Evolución Molecular , Proteínas/química , Proteínas/genética , Animales , Bacterias/química , Bacterias/metabolismo , Eucariontes/química , Eucariontes/metabolismo , Humanos , Modelos Moleculares , Estructura Terciaria de Proteína , Proteínas/metabolismo

RESUMEN

Different representatives of bacteria have different number of amino acid residues in the ribosomal proteins S1. This number varies from 111 (Spiroplasma kunkelii) to 863 a.a. (Treponema pallidum). Traditionally and for lack of this protein three-dimensional structure, its architecture is represented as repeating S1 domains. Number of these domains depends on the protein's length. Domain's quantity and its boundaries data are contained in the specialized databases, such as SMART, Pfam and PROSITE. However, for the same object these data may be very different. For search of domain's quantity and its boundaries, new approach, based on the analysis of dicted secondary structure (PsiPred), was used. This approach allowed us to reveal structural domains in amino acid sequences of S1 proteins and at that number varied from one to six. Alignment of S1 proteins, containing different domain's number, with the S1 RNAbinding domain of Escherichia coli PNPase elicited a fact that in family of ribosomal proteins SI one domain has maximal homology with S1 domain from PNPase. This conservative domain migrates along polypeptide chain and locates in proteins, containing different domain's number, according to specified pattern. In this domain as well in the S1 domain from PNPase, residues Phe-19, Phe-22, His-34, Asp-64 and Arg-68 are clustered on the surface and formed RNA binding site.

Asunto(s)

Proteínas Bacterianas/química , Bases de Datos de Proteínas , Proteínas Ribosómicas/química , Spiroplasma/química , Treponema pallidum/química , Proteínas Bacterianas/genética , Escherichia coli/química , Escherichia coli/genética , Estructura Terciaria de Proteína , Proteínas Ribosómicas/genética , Spiroplasma/genética , Treponema pallidum/genética

RESUMEN

AIM: to characterize the markers of endothelial dysfunction and the effect of antihypertensive drugs on them in patients with chronic urate tubulointestinal nephritis (UTIN) and articular gout. SUBJECTS AND METHODS: The study enrolled 81 patients aged 39 to 59 years with gout and urate nephropathy. All the patients were diagnosed as having grade 1-2 arterial hypertension. A lower glomerular filtration rate (GFR) was noted in 49.9%; microalbuminuria (MAU) and elevated serum endothelin-1 (ET-1) levels were recorded in all the patients. Combination antihypertensive therapy based on the use of angiotensin-converting enzyme (ACE) inhibitors and/or an angiotensin II receptor blocker (ARB) in combination with calcium channel blockers was performed during 12 months. The time course of changes in blood pressure, the parameters of target organ lesion, and the markers of endothelial dysfunction were monitored. RESULTS: Before the study, all the examinees were found to have MAU and increased serum ET-1, which are regarded simultaneously as signs of renal lesion and as markers of endothelial function. A combination of an ACE inhibitor or an ARB could diminish albuminuria and reduce ET-1 concentrations, lower systolic and diastolic blood pressure significantly, and increase GFR. CONCLUSION: The patients with articular gout and chronic UTIN are observed to have signs of endothelial dysfunction eliminated by combination antihypertensive therapy.

Asunto(s)

Antihipertensivos/uso terapéutico , Endotelio Vascular/fisiología , Gota/complicaciones , Hipertensión/etiología , Nefritis Intersticial/complicaciones , Ácido Úrico/orina , Bloqueadores del Receptor Tipo 2 de Angiotensina II/administración & dosificación , Bloqueadores del Receptor Tipo 2 de Angiotensina II/uso terapéutico , Inhibidores de la Enzima Convertidora de Angiotensina/administración & dosificación , Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Antihipertensivos/administración & dosificación , Biomarcadores/sangre , Bloqueadores de los Canales de Calcio/administración & dosificación , Bloqueadores de los Canales de Calcio/uso terapéutico , Quimioterapia Combinada , Endotelina-1/sangre , Endotelio Vascular/efectos de los fármacos , Femenino , Gota/sangre , Gota/tratamiento farmacológico , Gota/fisiopatología , Gota/orina , Humanos , Hipertensión/sangre , Hipertensión/tratamiento farmacológico , Hipertensión/fisiopatología , Hipertensión/orina , Masculino , Persona de Mediana Edad , Nefritis Intersticial/sangre , Nefritis Intersticial/tratamiento farmacológico , Nefritis Intersticial/fisiopatología , Nefritis Intersticial/orina , Albúmina Sérica/análisis , Resultado del Tratamiento

RESUMEN

Here we are the first to report that multifunctional Y-box binding protein 1 (YB-1) forms extended fibrils with a diameter of 15-20 nm. The YB-1 fibrils were visualized by atomic force and electron microscopy after 1-h incubation in solution with 2 M LiCl. Their length grew with incubation time and could exceed 10 microm; their shape is helical or zigzag-like. They possess polarity and tend to associate with one another to give structures of a higher order, like ribbons or bundles. The YB-1 fibrillar architecture has a distinct periodicity with a repeat unit of about 52 nm.

Asunto(s)

Proteína 1 de Unión a la Caja Y/química , Amiloide/química , Amiloide/ultraestructura , Humanos , Cloruro de Litio/química , Microscopía de Fuerza Atómica , Concentración Osmolar , Unión Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Factores de Tiempo , Proteína 1 de Unión a la Caja Y/genética , Proteína 1 de Unión a la Caja Y/aislamiento & purificación

RESUMEN

Reflux of gastric contents can be associated with many ENT disorders. Some authors describe an association with obstructive sleep apnea, but it is not clear whether the reflux causes the apnea or vice versa. Furthermore, authors did not distinguish between gastroesophageal reflux and extraesophageal reflux, which is essential to understand a connection with obstructive sleep apnea. Therefore, we performed polysomnography and two-channel pH testing simultaneously in patients with obstructive sleep apnea syndrome (OSAS) and compared the findings with data of healthy volunteers. After exclusion of a changed sleep architecture due to the pH testing system, the results show that patients with OSAS do not suffer more often from reflux than healthy volunteers. This is true for gastroesophageal as well as for extraesophageal reflux. Furthermore, an increasing number of reflux events during the night is not correlated with the number of apnea events. Thus, in summary our data cannot support the postulation that there is a connection between obstructive sleep apnea syndrome and reflux disease.

Asunto(s)

Reflujo Gastroesofágico/diagnóstico , Reflujo Gastroesofágico/epidemiología , Medición de Riesgo/métodos , Apnea Obstructiva del Sueño/diagnóstico , Apnea Obstructiva del Sueño/epidemiología , Comorbilidad , Femenino , Humanos , Incidencia , Masculino , Factores de Riesgo , Estadística como Asunto , Adulto Joven

RESUMEN

The dynamics of changes in spectra of oligosaccharide fragments formed during enzymatic degradation of plant pectins at low enzyme/substrate ratio was studied. It is shown that degradation of deesterified pectin molecules is a discrete and determined process manifested in establishment of a stable polysaccharide spectrum. It is noted that introduction of chemical modifications into the polysaccharide substrate structure preserves the discreteness of the polymer molecule fragmentation but changes the spectrum of formed oligosaccharide fragments. It is supposed that degradation is defined by the spatial (three-dimensional) organization of the polysaccharide molecule.

Asunto(s)

Pectinas/metabolismo , Poligalacturonasa/metabolismo , Cromatografía por Intercambio Iónico , Pectinas/química , Poligalacturonasa/aislamiento & purificación