Native form

The native form of chromatin in cells assumes a higher order stmcture called the 30-nm filament, which adopts a solenoidal stmcture where the 10-nm filament is arranged in a left-handed cod (Fig. 5). The negative supercoiling of the DNA is manifested by writhing the hehcal axis around the nucleosomes. Chromatin stmcture is an example of toroidal winding whereas eukaryotic chromosomes are linear, the chromatin stmctures, attached to a nuclear matrix, define separate closed-circular topological domains. 

Because of high interchain bonding, cellulose is insoluble in solvents and is incapable of flow on heating, the degradation temperature being reached before the material starts to flow. It is thus somewhat intractable in its native form. Cellulose, however, may be chemically treated so that the modified products may... 

Wild type Strain of microorganism isolated from nature. The usual or native form of a gene or organism. 

A stereocontrolled route to the native form of thromboxane B2 was carried out starting with a-methyl-D-glucoside (Ref. 3). 

Collectively known as the coinage metals because of their former usage, these elements were almost certainly the first three metals known to man. All of them occur in the elemental, or native , form and must have been used as primitive money long before the introduction of gold coins in Egypt around 3400 BC. 

As with organic solvents, proteins are not soluble in most of the ionic liquids when they are used as pure solvent. As a result, the enzyme is either applied in immobilized form, coupled to a support, or as a suspension in its native form. For production processes, the majority of enzymes are used as immobilized catalysts in order to facilitate handling and to improve their operational stability [24—26]. As support, either inorganic materials such as porous glass or different organic polymers are used [27]. These heterogeneous catalyst particles are subject to internal and external... 

Squalene epoxidase, like most enzymes responsible for the later steps of sterol biosynthesis [43, 51], is membrane-bound which makes its purification in native form challenging. The purification is additionally complicated by the presence of a large number of cytochrome P450 and other enzymes that have similar hydro-phobicity and size as squalene epoxidase and are hence difficult to remove [52]. Most studies have been carried out with rat liver microsome squalene epoxidase either partially purified or as a homogenate of the cell membrane fraction. In vitro reconstitution of squalene epoxidase activity is absolutely dependent on molecular oxygen, NADPH, FAD, and NADPH-cytochrome c reductase [52, 53]. In this respect, squalene epoxidase resembles the cytochrome P450 enzymes described... 

The active luciferase in the soluble luminescence system occurs in two molecular sizes, 130 kDa and 35kDa. The 130 kDa luciferase is the native form and occurs in extracts made at pH 8, and if luciferase is extracted with a pH 6 buffer, 130 kDa luciferase is converted into 35 kDa luciferase by the action of a protease (Krieger and Hastings, 1968 Fogel and Hastings, 1971 Krieger et al., 1974). The 130 kDa species is considered the naturally occurring form. 

Proguanil appears to have a dual activity. Part of it is metabolized to cycloguanil, which subsequently inhibits the protozaon dihydrofolate reduc-tase/thymidylate synthase (DHFR/TS) (Fig. 4). In addition, the native form, proguanil itself, exerts a potent antimalarial activity, especially in combination with other antimalarial drugs. The target of proguanil is unknown. 

Figure 4.14 Diagrammatic representation of (a) oxy-radical>mediated S-thioiation and (b) thiol/disulphide-initiated S-thiolation of protein suiphydryl groups. Under both circumstances mixed disuiphides are formed between glutathione and protein thiois iocated on the ion-translocator protein resulting in an alteration of protein structure and function. Both of these mechanisms are completely reversible by the addition of a suitabie reducing agent, such as reduced glutathione, returning the protein to its native form.

While PDF was originally proposed to be a zinc-metalloprotease [51], it is now generally accepted that Fe is the physiologically relevant metal ion occupying the active site in vivo [52], The native forms of most PDF enzymes are highly unstable due to propensity to oxidation, rendering them difficult to purify [53, 54], However, the Fe can be suitably replaced by either or Co, both of which provide a stable enzyme and main-... 

Copper (chemical symbol Cu, from the Latin name of the metal, cuprum), the metal that in Roman times was known as the Cyprian metal (since much of the metal came from Cyprus), is reddish brown, malleable and ductile, and can be easily shaped by cold- or hot-working techniques (see Fig. 35) (Scott 2002). Native copper occurs mainly in the form of boulders, nuggets, dendrites, and laminar outgrowths. It was certainly in its native form that copper was first recognized and used for over five millennia since then, however, the bulk of copper has been derived from copper ores by a variety... 

The development of novel pharmaceuticals species is tightly related to the mechanism of interactions between drugs and target integral membrane proteins. Solid-state NMR is highly attractive for these biological systems for two main reasons there is no limitation on molecular mass and it enables to study the membrane protein systems in their native forms. 

The dissolution of gold in its native form by cyanidation involves oxidation to Au1,... 

Raising the pi of macromolecules also can significantly alter the immune response toward them upon in vivo administration. Cationized proteins (those modified with diamines to increase their net charge or pi) are known to generate an increased immune response compared to their native forms (Muckerheide et al., 1987a, b Apple et al., 1988 Domen et al., 1987 Domen and Hermanson, 1992). The use of cationized BSA as a carrier protein for hapten conjugation can result in a dramatically higher antibody response toward a coupled hapten (Chapter 19). 

On the other hand, such approaches to the metalloenzymes described above in Figures 1 and 2 are still under way. Thus, the model clusters reproducing precisely their complex metal-sulfur assemblies in the native form have not yet been isolated. In this section, the studies aiming at the syntheses of the model compounds of two clusters in nitrogenase, FeMo cofactor and P-cluster, will be surveyed. The choice of these clusters as the representatives of the metal-sulfur clusters in metalloenzymes arises from the fact that these are the largest and most complicated metal-sulfur clusters known at present among those observed in natural enzymes. 

Oncaspar PEG L-asparaginase Enzon, Inc. and Rhone-Poulenc Rorere Acute lymphoblastic leukemia hypersensitive to native forms of L-asparaginase Feb. 1994... 

There are few drugs that are thioesters, but you may recall that one of the intermediates in the oxidation of aldehydes by aldehyde dehydrogenase is a thioester involving the thiol of the enzyme (Fig. 30 in Chapter 4), which is readily hydrolyzed back to the native form of the enzyme, a thiol, and the carboxylic acid product. Some drugs that are carboxylic acids, such as enaloprilate, are administered as ester prodrugs (enalopril), which are more readily absorbed from the intestine than the carboxylic acid and are then readily hydrolyzed to the active drug by esterases as mentioned in Chapter 1 (Fig. 1 in Chapter 1). 

Amino acids are separated in their native form on a sulphonated polystyrene resin using a system of sodium or lithium based buffers. Separation is effected by stepwise, rather than gradient elution, and the chromatography can be further optimized by carefully controlling the temperature of the analytical column. 

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