Thermal properties of frozen water in the native and amorphous starches with various hydration degrees.

The melting process of frozen water (FW) in various starches (rice, wheat, potato) that have crystal lattices of A- and B-type has been studied by means of differential scanning calorimetry (DSC). The dependences of the melting temperature (Tm) and heat (Qm) of FW on the size of the water clusters forming in starches with various humidity (the so-called size effect) and on conformational changes of starch molecules upon the destruction of native starch crystals (starch amorphization) have been considered. It has been found that in the native starches with low humidity (<35%) the Tm of FW lies below 0 °C and decreases with the decrease of their humidity.

[Peculiarities of wound infections in severe burns].

Infections in patients with burns remain as a one of the main unsolved problems. The present work is based on the analysis of the data obtained from the 642 patients with burns (adults and children) during 2000-2005. The staphylococcus infection is still the leading.

[Thermostability of DNA and its connection with the glassing process].

Using differential scanning calorimetry, the thermal denaturation of calf thymus DNA with different content of water (from 12 to 92%) was investigated. Dependences of melting temperature and enthalpy on the biopolymer hydration degree were established. Within the range of water concentrations from 92 to 50% the values of thermodynamic parameters of denaturation were obtained being in good agreement with the published data.

[Formation and melting of ordered structures in denatured myoglobin with differing water content: differential scanning calorimetry method].

The possibility of superstructure formation in denatured globular proteins has been studied through the temperature dependence of the absolute values of heat capacity in the myoglobin-water system with water content from 80 to 25% in the temperature range 20-160 degrees C. For all the composition range studied it is found that after the denaturation of myoglobin the new regular structures with reversible melting are formed. These structures are similar in properties to the thermotropic gels in concentrated myoglobin solutions.

[Thermal characteristics of a collagen-water system. II. Conformationalmobility of macromolecules in native and denatured states].

By calorimetric study of the collagen-water systems with 10-100% content of protein in the temperature range 20 + 90 degrees C we have measured the proper heat capacity of protein in native and denatured state. It is shown that S-like dependence of heat capacity on the water content for both native and denatured samples is caused by glass transition. At temperatures above the glass transition in moist collagen or above the denaturation of native collagen the translational mobility of segments in protein molecules appears.

[Thermal properties of collagen-water system. 1. Increments of heat capacity during denaturation and glass transition].

The absolute values of heat capacity of the collagen-water systems with different relative content of the components in both native and denatured state were studied by the method of differential scanning calorimetry in a wide temperature range (-40 +/- 140 degrees C) which includes the region of the denaturation phase transition as well as the region of the relaxation glass transition. From the experimental data the values of denaturation increment delta Cpnd-0.42 +/- 0.

[Melting of ordered structures in denatured collagen depending on biological age by differential scanning calorimetry].

Using the differential scanning calorimetry we were able for the first time to establish the correlation between the biological age of the collagen tissue (rat tail tendon, age from 20 days to 24 months) and the melting parameters of gels, which are formed after the collagen denaturation. We have found that the half-width of the gel melting curves delta T1/2, as well as the ratio of the gel melting heat to the denaturation heat Qm/Qd are sensitive to the biological age of the tissue. The gel melting temperature Tm, in distinction to the denaturation temperature, was found to be not sensitive to the age but entirely dependent on the gel formation temperature.

[Parameters of heat disruption of native collagen structures and their connection with biological growth].

By means of differential scanning calorimetry we have studied the influence of structural changes induced by the biological aging on the processes of thermal denaturation of collagen tissue (rat tail tendon, age from 14 days to 24 months). We have found that some parameters of the thermal denaturation process, namely, the denaturation temperature Td and the denaturation heat Qd are sensitive to the biological age of the tissue. Both Td and Qd are increasing with the age.

[New data on heat denaturation of collagen fibrils].

Using the differential scanning calorimetry we have found that the structural changes due to the aging have the influence on the temperatures of denaturation and the values of denaturation heats of the intact collagen (rat tail tendon). The magnitude of the specific heat jump at denaturation of the collagen fibrills differs from that for the isolated molecules.

[Denatured increments of heat capacity in globular proteins and its connection with vitrification processes].

Absolute values of heat capacity for some hydrated globular proteins have been studied by differential scanning calorimetry (DSC) method. It has been found that for the proteins with completely bound water, like in the case of protein solutions, the value of heat capacity of denatured proteins is higher than that prior to denaturation. Depending on temperature and humidity the denatured proteins can be either in high elastic or glass state.

[Calorimetric study of the glass transition of denatured collagen].

Temperature dependence of heat capacity of native and denatured collagen samples with different content of bound water (6 divided by 27%) has been studied by DSC method in the temperature range from -50 to 150 degrees C. Heat capacity of denatured samples demonstrates a jump of 0.50 J/g.

[Jump-like change in the heat capacity of denatured biological macromolecules].

Study of temperature dependence of heat capacity in denatured biopolymers (collagen, elastin, lysozyme, DNA) with 10-15% of bound water revealed a characteristic jump at some critical temperature Tc. It is argued that such behavior reflects glass transition in biopolymers.

[Thermal denaturation of collagen in solutions and fibrils].

Thermal denaturation of rat skin collagen in fibrils and water solutions has been studied by differential scanning calorimetry. Heating rates in the range 0.3-25 K/min were used.