Preferential utilization

Figure 10.4. Effect on apatite-collagen isotopic fractionation due to inhibition of amino acid production and preferred use of exogenous amino acids. Carnivore and herbivore, both based on C3 plants, have similar bulk isotopic composition of total edible tissues (T), leading to similar 5 C for apatite carbonate (AP). Collagen (CO) of carnivore is more enriched in Cthan that of herbivore, because of preferential utilization of amino acids derived from protein (P) of herbivore flesh in construction of carnivore s proteins. C ss = assimilated carbon.

Bouzier, A. K., Voisin, R, Goodwin, R. etal. Glucose and lactate metabolism in C6 glioma cells evidence for the preferential utilization of lactate for cell oxidative metabolism, Dev. Neurosci. 20 331-338,1998. 

The phototrophs that assimilate fixed nitrogen preferentially utilize ammonium over nitrate or nitrite. (Some phototrophs assimilate DON, such as urea, to meet their nitrogen needs, and, hence, are not strict autotrophs.) Ammonia is fevored over the more oxidized forms of DIN as less redox energy is required to incorporate its nitrogen into biomolecules, primarily amino acids and the nucleotide bases. 

Schroeder, H.W., Wang, J.Y. (1990). Preferential utilization of conserved immunoglobulin heavy chain variable gene segments during human fetal life. Proc. Natl. Acad. Sci. USA, 87, 6146-6150. 

S. thermophilus metabolizes lactose to l( +) lactic acid but utilizes only the glucose moiety of lactose, leaving the galactose moiety in the cheese (Tinson et al. 1982). In Swiss cheese manufacture, S. thermophilus metabolizes the lactose and L. helveticus metabolizes the galactose to d( —) and l( + ) lactic acid (Turner et al. 1983). The l( + ) lactate isomer is preferentially utilized by propionibacteria to form acetic and propionic acids, which are essential for the development of the characteristic flavor in Swiss cheese (Langsrud and Reinbold 1973). 

Yancopoulos, G.D., Desiderio, S.V., Paskind, M., Reamey, J.F., Baltimore, D., Alt, F.W. (1984). Preferential utilization of the most / -proximal VH gene segments inpre-B-cell lines. Nature 311, 727-733. 

Ogawa, S., Oku, A., Sawano, A., Yamaguchi, S., Yazaki, Y. and Shibuya, M. (1998) A novel type of vascular endothelial growth factor, VEGF-E (NZ-7 VEGF), preferentially utilizes KDR/Flk-1 receptor and carries a potent mitotic activity without heparin-binding domain. J. Biol. Chem., 273, 31273-31282. 

Bernier, R., and F. Stutzenberger. 1987. Preferential utilization of cellobiose by Thermomonospora curvata. Applied and Environmental Microbiology 53 1743—1747. 

The preferential utilization of glutamine as an energy source is cell-dependent. Maranga and Goochee (2006) have demonstrated that PER.C6 cells fall into a minor category of mammalian cell lines for which glutamine plays a minor role in energy metabolism. 

Ion exchange or sorption can also occur on colloids, since colloids possess an electric surface charge, at which ions can be exchanged or sorptively bound. The proportion of colloids not caught in small pores preferentially utilizes larger pores, thus sometimes travelling faster than some of the water in groundwater (size-exclusion effect). That is why the colloid-bound contaminant transport is of such special importance. 

Waniewski RA, Martin DL (1998) Preferential utilization of acetate by astrocytes is attributable to transport. J Neurosci 18 5225-5233... 

Classically, this separation of roles was accomplished by utilizing substrates that differed drastically in their ability to form enolate anions. In fact, the various name reactions mentioned above are distinguished not by basic differences in mechanism, but by the nature of the components preferentially utilized as substrates. For example, in the Perkin reaction, the condensation of an aromatic aldehyde with an aliphatic acid anhydride is based on the fact that the electrophilic component, e.g. benzaldehyde, lacks a-hydrogens and therefore is incapable of forming an enolate. At the same time the utilized electrophile, acetic anhydride, contains a carbonyl group with reduced propensity to interact with nucleophiles. Hence, it is incapable of undergoing self-condensa-... 

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