Carbohydrate glucose pool

This was possible to detect because the monoculture of Thalassiosira rotula employed showed partly synchronized cell divisions during exponential growth. Brockmann et al. [137] carried out combined measurements of dissolved amino acids and carbohydrates. Glucose and lysine occurred in highest concentrations. Mague et al., [22] found that extracellular production of free amino acids counted for 7.1% of the of the total extracellular C released in an exponentially growing culture of S. costatum Myklestad et al., [26] measured 10.7% for C. affinis or 3.6% when calculated as percent of total incorporated cell N. In contrast to this Admiraal et al., [139] found that none of three benthic diatoms released more than 0.1 % of the cellular N as free amino acids and concluded that benthic diatoms may act as net consumers of amino acids. Several authors did measure both intracellular and extracellular concentrations of many amino acids [22 140 -142]. The clear difference in relative composition of intracellular and extracellular fractions as pointed out by the first mentioned of these authors, show that the released pool is not just a portion of the intact cells content. 

The available pool of amino acids present in juice is not sufficient, by itself, to account for levels of fusel oils found in wine (Reed and Nagoda-withana, 1991). Its now known that they arise from not only amino acids, by the pathway described above, but from carbohydrate (glucose) sources as well (Thoukis, 1958) and over the course of fermentation (Castor and Guymon, 1952 Muller et al., 1993). 

FIGURE 16.12 Enzymatically synthesized amylose"-type nb/lcb glucans ( ) with a significant amount of the substrate glucose-1-PO4 separated on Sephacryl S-SOO/S-IOOO (60 + 9S x 1.6 cm) 3-ml fractions were collected for further analysis normalized (area = 1.0) eluogram profiles (ev) constructed from an off-line determined mass of carbohydrates for each of the pooled fractions flow rate 0.42 ml/ min V,xd = 126 ml, V , = 273 ml eluent O.OOS M NaOH. 

Several sugar-nucleotide pool defects have been identified Type I carbohydrate-deficient glycoprotein syndrome (CDGs type I), a defect in phosphomannomu-tase, one of the enzymes responsible for converting glucose to GDP-mannose, results in an absence of... 

Although carbon dioxide is plentiful in the natural environment it is only used in algae by photosynthesis. The usual source of carbon is via carbohydrates. Monosaccharides such as glucose are not found in nature, probably because if they are present they are rapidly utilised by cells [Lynch and Poole 1979]. Laboratory experimentation on the other hand, often uses glucose as a carbon source for the... 

The human body has the capacity to store carbohydrate in the form of muscle and liver glycogen, and to store fat as triglycerides in adipose and muscle tissue. However, there is no comparable storage pool for protein. Yet, under conditions of energy or protein deficit, proteins that serve a variety of functions must be catabolized. When needed, the body can utihze skeletal muscle protein as a somewhat dispensable protein and energy reserve. With an inadequate supply of protein, AAs can be mobifized from muscle protein catabolism and used to synthesize proteins more essential to survival than skeletal muscle. Similarly, with an inadequate supply of carbohydrate, AAs from protein catabohsm are used as substrate for gluconeogenesis to maintain an adequate supply of blood glucose. 

The citrate cycle is not only a degradative scheme, but at the same time furnishes a general pool of intermediate products. It accepts the C2 fragments from carbohydrate, fat, and protein catabolism it is involved in the synthesis of glucose (which will be discussed in Chapt. XV, the key substance being oxaloacetate) it provides the raw material for the synthesis of several amino acids, aspartate and glutamate, for example. Finally, the blood pigment also arises from succinyl-CoA, another intermediate of the cycle. 

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