Metabolic pathway affected

H. G. Holzhtitter, G. Jacobasch, and A. Bisdorff, Mathematical modeling of metabolic pathways affected by an enzyme deficiency. A mathematical model of glycolysis in normal and pyruvate kinase deficient red blood cells. Eur. J. Biochem. 149(1), 101 111 (1985). 

Several other genetically determined metabolic pathways affect the rate and degree of metabolism of phenelzine (Nardil) and certain benzodiazepines. Unpredicted medication responses to these agents are potentially linked to altered metabolism. 

The biochemistry of conjugation has been thoroughly reviewed in the recent publications of Caldwell (2), Hiron and Millburn (2), and a previous ACS Symposium Series monograph (4). Glucuronidation is the most versatile and quantitatively important metabolic pathway affecting a diverse group of substrates including alcohols, carboxylic adds, amines, and sulfur compounds (2.41. 

Hormone Function Major Metabolic Pathways Affected... 

Different enzymes and different tissue sites differ in the tenacity with which they can retain flavin coenzymes in times of riboflavin deficiency, so there is a characteristic pecking order for flavoen-zyme protection, which appears to reflect the metabolic importance of the different metabolic pathways affected. Apart from this pecking order, however, there is no repository of unused or nonfunctional riboflavin that can act as a store in times of dietary deficiency. Although some organs (such as liver) have relatively high concentrations of flavin enzymes, all of the flavin seems to be present as coenzyme moieties of flavin holoenzymes. Each tissue has a characteristic ceiling level of riboflavin at saturation, and a floor level characteristic of severe depletion, and these are determined, respectively, by the total amount of apoflavoprotein, and the amount of resistant holoenzyme, which cannot be depleted of its cofactor during riboflavin deficiency. 

The significance of pH is particularly interesting since pH may either augment or diminish NH3 production. The possible mechanisms by which pH affects NH3 production are (a) inhibition of bacterial metabolism, (b) pH-dependent changes in urea metabolic pathways, (c) pH-dependent bacterial utilization of glucose and urea as energy sources, and (d) increased bacterial uti-... 

Since the SUMO pathway affects multiple pathways ranging from transcription, DNA repair, and intracellular trafficking over cell signaling and cell cycle control to basic metabolism, it is not suiprising that links to diseases and viral assaults are emerging. However, the field is not yet at a stage sufficiently developed for pharmacological intervention. Below we will describe selected examples for links of the SUMO pathway to diseases and viral functions. 

Some aspects of the biochemistry of metabolic processes affecting nutrients appear to have significant consequences for the expected behavior of stable carbon isotopes as tracers of diet. Specifically, we have seen that the simple model of a total scrambling of carbon atoms during endogenous biosynthesis is inconsistent with the expected pathways of some nutrients, whereas other isotopic records in ancient human tissues can be adequately accounted for by this model. 

Metabolic pathways are regulated by rapid mechanisms affecting the activity of existing enzymes, eg, allosteric and covalent modification (often in response to hormone action) and slow mechanisms affecting the synthesis of enzymes. 

In Fig. 5, the biosynthetic pathways for the production of PHA with novel composition of hydroxyalkanoates and the enzymes involved are shown. The level of metabolic intermediates, which is determined by the cellular metabolic activities, is important for the synthesis of a desired PHA. Having the engineered metabolic pathways at hand, PHA synthase plays an important role affecting the composition of PHAs, because of substrate specificity of PHA synthase. 

Insect metabolic pathways, compounds affecting, 14 345 Insect pheromones, 14 346 Insect repellents, 14 345 Insect-resist agents, for wool treatment, 26 403-404... 

There are now thought to be several thousand different genetic diseases, about 10% of which have known biochemical lesions. As has already been seen with the thyroid diseases and diabetes, the phenotypic manifestation, hemophilia, for example, may have genetically, biochemically or clinically different causes. Some of the biochemically identified disturbances, such as those affecting glycogen or galactose, have been important in establishing metabolic pathways (see Chapter 4). 

We think about metabolic pathways as linear or cyclical sequences of reactions as described in Chapter 1. Individual reactions within a pathway are often dependant upon at least one other reaction. For example, we know from our studies of enzyme kinetics in Chapter 2 that the rate of an enzyme catalysed reaction is determined in part by the concentration of substrate. Remember, the substrate for one reaction is usually the product of a previous reaction, so the activity of an enzyme is affected by the activity of the preceding enzyme in the sequence. 

Phytoremediation of organic xenobiotics is generally based on mineralization or more frequently on degradation/transformation of the xenobiotics to environmentally less dangerous compounds, which are fixed in cell compartments or stored in the vacuole as soluble products or exuded back to the environment. Affection of the metabolic pathway by suppression or enhancement of expression of enzyme leading particular... 

A successful tool in the early studies of metabolic pathways was blocking the pathway at some specific point. This could be done by the use of either mutants or inhibitors. Schekman et al have isolated a number of yeast mutants with blocks in their secretion pathway (Schekman, 1982). It is not yet known which proteins these mutations affect, but this is clearly a most promising approach for identifying those components involved in transport. In animal cells there are no cellular mutants with blocks in the intracellular transport of protein from the ER to the cell surface. There are, however, genetic diseases which affect the routing of lysosomal enzymes to the lysosomes (Neufeld et al, 1975 Sly and Fischer, 1982). For viruses it has been possible to isolate temperature-sensitive mutants in which a mutation in the viral glycoprotein arrests... 

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