Substances bound

Riboflavin was first isolated from whey in 1879 by Blyth, and the structure was determined by Kuhn and coworkers in 1933. For the structure determination, this group isolated 30 mg of pure riboflavin from the whites of about 10,000 eggs. The discovery of the actions of riboflavin in biological systems arose from the work of Otto Warburg in Germany and Hugo Theorell in Sweden, both of whom identified yellow substances bound to a yeast enzyme involved in the oxidation of pyridine nucleotides. Theorell showed that riboflavin 5 -phosphate was the source of the yellow color in this old yellow enzyme. By 1938, Warburg had identified FAD, the second common form of riboflavin, as the coenzyme in D-amino acid oxidase, another yellow protein. Riboflavin deficiencies are not at all common. Humans require only about 2 mg per day, and the vitamin is prevalent in many foods. This vitamin... 

A number of transport mediators are transport proteins in the absence of an external energy supply, thermal motion leads to their conformational change or rotation so that the transported substance, bound at one side of the membrane, is transferred to the other side of the membrane. This type of mediator has a limited number of sites for binding the transported substance, so that an increase in the concentration of the latter leads to saturation. Here, the transport process is characterized by specificity for a given substance and inhibition by other transportable substances competing for binding sites and also by various inhibitors. When the concentrations of the transported substance are identical on both sides of the membrane,... 

Substances bound include endogenous compounds—bilirubin, estradiol, cortisol, and also drugs such as tetracycline, penicillin, and ethacrynic acid. 

In addition, chiral dendrimers (see Section 4.2) can be resolved with the aid of HPLC into their enantiomers, if the silica gel material used as stationary phase has optically active substances bound to its surface [9]. Since the chiral stationary phase (CSP) [10] undergoes different intensities of interaction with the enantiomeric dendrimers, they are retained to different degrees, and in the ideal case two completely separated (baseline separated) peaks are obtained. This separation technique was successfully applied inter alia to racemic mixtures of planar-chiral dendro[2.2]paracyclophanes, cycloenantiomeric dendro[2] rotaxanes, topologically chiral dendro[2]catenanes [11] as well as topologically chiral, dendritically substituted molecular knots (knotanes) [12] (Section 4.2.3). 

The only substances bound are those possessing the same pharmacological mechanism of action (specificity). 

Complex, blood-group-active substances have been employed as inhibitors of hemagglutination.196,693 Osawa and Matsumoto found692 inhibition of both Ulex lectins by human A-, B-, and H-active substances, whereas Lea substance and porcine, submaxillary mucin bound only to Ulex II. Chuba and coworkers693 reported that substances from porcine stomach (A-active), equine stomach (B-active), and baboon stomach (A-, B-, and O-active substances), as well as human A-, B-, and O-active substances, bound equally well to both U. europeus lectins. However, porcine, submaxillary mucin and nonsecretor saliva inhibited only Ulex II activity. 

The amount of flavouring substance bound by fat or oil depends on the chain length of the volatile compound within a homologous series. Thus, for instance, the distribution coefficient in oil-in-water systems increases with the increasing chain length of... 

Mechanism (1) is particularly important in peat and other organic-rich sediments, where clay and metal complexes are present in very low amounts in relation to the humus component. A typical example of humic substances bound by polyvalent complexes (item 2) is the Spodosol. These soils have developed under climatic and biologic conditions that have resulted in the mobilization and transport of considerable amounts of iron, aluminum, and organic matter into the B horizon. This illuvial horizon is a rich source of fulvic acids, which are readily separated from the sesquioxides by mild extractants. 

Melanin is an extremely inhomogeneous substance, bound to protein, (cf. 581a), and also binding metals such as iron (e.g., 531, 532). It is probable that a pure melanin, in the sense of a product derived from a single precursor, rarely occurs naturally. 

At present, several research groups are engaged in preparing suitable layers or membranes for this purpose. Compared to biosensors, these layers are far more stable and they can be prepared for a large variety of compounds. Compared to standard chemosen-sors they are far more selective, so that there is a good chance of a broad application. It is still necessary to develop extremely sensitive methods for detecting substances bound to the imprinted membrane. At present, conductometry [57, 70, 71, 106, 153, 154], capacitance [155], pH-potentiometry [41], voltammetry [69], optical detection [87, 156],... 

PROC 24 High (mechanical) energy work-up of massive metals or substances bound in materials and/or articles... 

In the strictly scientific sense, adhesion is the attraction between molecules across an interface. The receiving surface is termed the adherent and the material bound to it is the adhesive. According to this definition, the strength of the adhesion is determined by the number of contact points per unit surface area and the magnitude of the attraction forces at these points. In this definition, adsorption would be the decisive quantity, and it would only be necessary to allow for the forces between the adsorbent (the substrate) and the adsorbate (the substance bound to the surface). 

Marchlewsbca-Koj (330) fractionated male mouse urine and found that the pregnancy-blocking pheromone is a peptide or a substance bound with the peptide fraction. 

The majority of enzymes are based on complex, high-molecular-weight proteins, but there are exceptions, such as the ribozymes, which are RNA-based. Some proteins may themselves act as efficient catalysts, but many require the assistance of smaller entities to achieve this. Such substances, bound to the protein, are termed cofactors. 

Some emphasis is put upon the dimensionless numbers D-t and h-L/D, as well as M/M or M/M and C/Cjn. By using them, the kinetics or the profiles of concentration obtained in typical cases are transformed into master curves which can be used whatever the nature of the diffusing substance-polymer couple and the other parameters, e.g., the dimension of the film and the time, as well as the initial concentration of the substance bound to diffuse. 

Fig. 2. Infantile amaurotic family idiocy. Cerebral cortex. HE-stain. Enlargement 150-fold. All ganglion cells are ballooned and store gangliosides. Small dark glial cells surround ganglion cells and contain the storage substance bound to protein. (Reproduced by courtesy of Prof. P. B. Diezel)...

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