Characterization tests carbohydrates

From a strategic perspective, product characterization is paramount to the development of identity, purity, or assay procedures since it involves the determination of many of the structural and physicochemical properties of the product under study. Consequently, product characterization is, by necessity, first in the series of test procedures to be developed. For glycoproteins, in addition to the more basic structural properties inherent to proteins such as amino acid sequence and higher-order structural elements (i.e., secondary, tertiary, and quaternary structures), in-depth characterization of carbohydrate-mediated properties are required. 

Although a number of assays and technologies are available to characterize and test protein molecules, such as peptide mapping, protein sequencing, carbohydrate analysis, electrophoresis, ELISA, and mass spectroscopy, they are not as definitive as the methods used for small molecule drugs. Hence, the test for similarity is not as well defined in the case of proteins. However, as... 

Myophosphorylase deficiency is the classic example of a carbohydrate-related dynamic syndrome. Affected persons are unable to mobilize glycogen therefore they cannot perform high-intensity work and must rely extensively on lipid metabolism. Several other defects of glycolysis produce similar symptoms. All are characterized by inability to do anaerobic work and to produce lactate during ischemic exercise, which is the basis for the customary screening test for these disorders. Patients are asked to perform maximal hand grip contractions at the rate of one per second for 60 seconds with the forearm circulation... 

Steroid hormones (Section 21.8) are produced by the adrenal cortex and the gonads (testes in males, ovaries in females). The adrenocortical hormones include glucocorticoids, which affect carbohydrate metabolism, modulate inflammatory reactions, and are involved in reactions to stress. The mineralocorticoids control the level of excretion of water and salt by the kidneys. If the adrenal cortex does not function adequately, one result is Addison s disease, characterized by hypoglycemia, weakness, and increased susceptibility to stress. This disease is eventually fatal unless it is treated by administration of mineralocorticoids and glucocorticoids to make up for what is missing. The opposite condition, hyperfunction of the adrenal cortex, is frequently caused by a tumor of the adrenal cortex or of the... 

Two approaches to measuring enzymatic activity exist. In vitro tests use commercially available isolated enzymes that have been purified and characterized. In medical laboratories in vitro enzyme tests are used as diagnostic aids to determine blood constituents. In food chemistry, carbohydrates, organic acids, and alcohols are quantified by using isolated enzymes. The second method is to determine the activity of enzymes in vivo. A synthetic substrate labeled with a chromophore is added to the sample. The enzyme in the sample catalyses the cleavage of the substrate chromophore bond and the chromophore can be detected photometrically or fluorom-etrically. The amount of dye released per hour corresponds to the enzyme activity as substrate turnover per hour. 

Two monosaccharides may be combined with the loss of one molecule of water to form a disacchaiide. Polysaccharides and other complex carbohydrates are then produced by the condensation of more monosaccharide subunits with the loss of a molecule of water for each additional monosaccharide. Depending upon its constitution, hydrolysis of a polysaccharide yields either a single monosaccharide or a mixture of monosaccharides. In this chapter, some of the fundamental chemical and physical properties of carbohydrates will be investigated using simple mono-and disaccharides several classic qualitative tests to characterize and classify carbohydrates will also be performed. 

---