Study of Biological Materials

The Mossbauer spectra of Fe + complexes with guanine, guanosine, and ribose have been investigated at 77K. The study indicates the influence of the sugar on the shape of the spectra of the investigated complexes of iron. The Mossbauer spectra of complexes of Fe + with ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) point to the difference in the electron donor properties of these biopolymers (caused by the structure of the sugar of the polymeric chain of nucleic acid). 

The Mossbauer effect has also been useful in the study of the chemical states of iron in intact cells of nitrogen-fixing bacteria. Mossbauer spectroscopy has also been used to study iron uptake and translocation in rice plants by Kilcoyne et al. (2000) who have collected spectra from intact root and leaf tissue of rice plants grown in anaerobic Fe(II)-enriched nutrient solutions. The spectra obtained from root tissue of plants grown in nutrient solutions typical of paddy soils arise primarily from Fe(III)-oxide components precipitated on the root cell walls. In contrast, the spectra obtained from root tissue from plants exposed to lower, toxic, pH conditions show that, in addition to Fe(III), uncomplexed Fe(II) is taken up. No evidence of Fe(II) was seen in the leaf tissue of any of the plants, where the spectra are characteristic of Fe(III) in ferritin and other complex forms. 

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It is now clear that in the absence of molecular oxygen most proteins phosphoresce in aqueous solutions at ambient temperature.(10) In this chapter we discuss the use of phosphorescence of tryptophan to study proteins, with emphasis on measurements at room temperature. Comparisons between phosphorescence and the more commonly used fluorescence spectroscopy are made. Comprehensive reviews of protein luminescence have been written by Longworth.(n 12 1 A discussion on the use of phosphorescence at room temperature for the study of biological materials was given by Horie and Vanderkooi.(13)... 

A complication in the study of biological materials is that the species of an element which are either formed and/or take part in physiological reactions in different compartments may vary. It is therefore necessary, especially during the sampling and pretreatment steps, that the constituents from different compartments are very carefully separated. For example, in the study of the speciation of an element in blood serum contaminants originating from the erythrocytes could lead to errors in the results. 

We do not wish to argue the importance of the chemical vs. the biological role in specific equilibrium reactions but rather to bring to attention certain studies of biological material which suggest a role in determining the chemical composition of the aquatic environment, with special reference to the fresh water environment. 

The gold clusters appear to be ideal models for bulk metals, metal surfaces, and colloidal particles. The gold clusters are used for labelling in electron microscopy studies of biological materials. 

The H has been the traditional nucleus for biological studies in the past decade and researchers have successfully utilized multidimensional NMR methods to assign spectra for proteins up to 30 kDa. Other nuclei such as C, N, and P have been used but their lower gyromagnetic ratios and/or natural abundances reduce sensitivity unless expensive isotopic enrichment methods are employed. An alternative nucleus for studies of biological materials is F. F NMR is a powerful technique due to several unique... 

In this article, examples are chosen from recent literature to highlight progress in the NMR study of biological materials. Many emphasise the need for a careful choice of experimental procedure and/or instrumental design. The field is now expanding and too large to cover comprehensively, but several review articles on previous work are available e.g. enzymes [9-12], protein structure [13-16], interactions of biological molecules [17-19], and medicinal chemistry [20]. 

Many different spectroscopic techniques have been employed in the study of biological materials. These methods include optical absorption, infrared and Raman spectroscopy, electron spin resonance (ESR), nuclear magnetic resonance (NMR) and more recently Mossbauer effect spectroscopy. 

The ESR technique has been employed for many years in the study of biological materials and several books dealing with ESR and its applications are in existance (21—25). A comprehensive treatment of the entire field of ESR by Abragam and Bleaney (26) has recently appeared. The reader is encouraged to consult these references for the experimental details and the general discussion of spin resonance. 

Interest in pressure as a thermodynamic and kinetic variable has been growing also in physico-chemical studies of biological materials in recent years [9-18]. The fundamental reasons why it can be desirable to carry out high pressure experiments on these systems are i) Changing temperature of a biochemical system at atmospheric pressure produces a simultaneous change in thermal energy and volume therefore, to separate thermal and... 

Kimmel and Saifer (1964) have recorded the infrared spectra of the 2,4-dini-trophenyl (DNP) and 3-phenyl-2-thiohydantoin (PTH) derivatives of 27 amino acids of importance in the study of biological materials, e.g., plasma, tissues, and urine. These workers have also made a quantitative study of the intensities of the major absorption bands according to the method of Flett (1962), and showed that the infrared spectra of DNP- and PTH-amino acids are a useful means for the determination of the N-terminal residues of various peptides and proteins, especially when used in conjunction with thin-layer chromatography. 

A very considerable number of elements has been shown to occur in a wide range of animal tissues and fluids in such minute amounts that they can appropriately be described as traces. Numerous studies of biological materials from widely separated sources have established the fact that copper, manganese, zinc, iodine, cobalt, nickel, aluminum, chromium, tin, silicon, titanium, lead rubidium, lithium, molybdenum, arsenic, fluorine, bromine, barium, and strontium are commonly present in low concentrations in blood, milk, and tissues of higher animals, and other metals, such as silver, gold, boron, cadmium, and cerium are occasionally present. No doubt others will be detected as more-refined analytical methods are developed. 

A further feature of modern Raman spectroscopic microscopes is that the laser is polarized, allowing determination of, for example, depolarization ratios, and molecular orientation in crystals or liquid crystals. Care must be taken to account for the polarization response of the vertically ruled diffraction grating however. To date, there have been few or no polarization dependent studies of biological materials although recent studies have demonstrated that polarization dependent Raman can detect structural changes in the extracellular matrix associated with basal cell carcinoma. ... 

The study of cementitious materials in the TEM is much, much more difficult than the SEM studies discussed previously. Unless you have at least 1 year to devote to learning about sample preparation and observation, we do not recommend even considering the technique. Very few staff in centralised facilities have experience with cementitious materials, which are very different from both classic inorganic materials (metals and ceramics) and from studies of biological materials or polymers. 

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