Fatty acids, activation description

Conductivity, in water activity measurement, 67-70 Confocal laser scanning microscopy to characterize lipid crystals, 575-579 description of, 575, 577 Conjugated dienes and trienes, determination of, 515-517 Conjugated linoleic acid (CLA), fatty acid analysis, 437-438, 445-446 Convection oven, gravimetric measurement of water, 7-8, 10-11... 

Soluble amphiphiles are also known as detergents, tensides, or surfactants. Perhaps the most descriptive of these words is the word surfactant, which is a contraction of the phrase surface active agent . The term soap is usually restricted to the alkali metal salts of long-chain fatty acids (Table 12.1). The term amphiphile indicates that one part of the molecule likes a certain solvent while the other part likes another solvent and the two solvents are immiscible. Usually one solvent is water and the water-loving part is called hydrophilic. The other part is hydrophobic. It does not like to be in water and prefers to be in an oily environment or air. The hydrophobic part usually consists of a long, straight alkyl chain (CH3(CH2) c i nc = 8-20). For special applications the hydrocarbons might be completely or partially fluo-rinated. 

A rigorous kinetic description of interfacial catalysis has been hampered by the ill-defined physical chemistry of the lipid—water interface (Martinek et ai, 1989). Traditional kinetic assumptions are undermined by the anisotropy and inhomogeneity of the substrate aggregate. For example, the differential partitioning of reactants (enzyme, calcium ion, substrate) and products (lysolecithins, fatty acids) between the two bulk phases prevents direct measurement of enzyme and substrate concentrations. This complicates dissection of the multiple equilibria that contribute to the observed rate constants. Only recently has it become possible to describe clearly the activity of SPLA2S in terms of traditional Michaelis— Menten kinetics. Such a description required the development of methods to reduce experimentally the number of equilibrium states available to the enzyme (Berg etai, 1991). 

Evidence so far indicates that substrate and cofactor availability, and product inhibition, constitute the main modes for the regulation of fatty acid oxidation within mitochondria there is nothing to indicate that substrate flow over the p-oxidation spiral is further regulated by allosteric or covalent modification of the activity of any enzyme of this spiral. As is to be expected for a multistep metabolic pathway, diverse steps contribute to the overall regulation of fatty acid oxidation in different tissues under different conditions. /S/lore is known about this process in liver and heart than in other tissues and its brief description follows. 

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