Biomolecules derivatives

Figure 24.29. Selected Biomolecules Derived from Amino Acids. The atoms contributed by amino acids are shown in blue.

The carbon skeleton of cholesterol and those of all biomolecules derived from it originate with the acetyl group (a Ca unit) of acetyl-CoA. 

Patients usually need months of treatment (100-200 treatments), with about 70% of patient responding after 1-2 years. The expected response is related to the development of multiple perifollicular macules of repigmentation and contraction in size. Nevertheless, if after 4—6 months or 30-50 treatments, the patient does not respond, PUVA should be discontinued. Stable disease, for at least a year, is usually easier to treat. Completely repigmented areas can be stable for a decade or more without relapse, but if a lesion is not fully repigmented, reversal of acquired pigmentation may occur when treatment is discontinued [104,122]. KUVA and topical PUVA are alternative treatments to oral PUVA in vitiligo patients. KUVA uses an organic biomolecule derivate of 1,4-benzopyrone and furan called khellin as photosensitizer, and this is not phototoxic. Topical PUVA may be suitable for small lesions, while UVA alone is of limited benefit [122]. 

LB Films of Porphyrins and Phthalocyanines. The porphyrin is one of the most important among biomolecules. The most stable synthetic porphyrin is 5,10,15,20-tetraphenylporphyrin (TPP). Many porphyrin and phthalocyanine (PC) derivatives form good LB films. Both these molecules are important for appHcations such as hole-burning that may allow information storage using multiple frequency devices. In 1937 multilayers were built from chlorophyll (35). 

Interaction of biomolecules with ginghaosu (artemisinin) and its derivatives in the presence of Fe(II) ion—an exploration of antimalarial mechanism 99PAC1139. 

Mechlorethamine (nitrogen mustard) In vivo each chloroethylamine group undergoes intramolecular cy-clization with release of a chloride ion. The so formed highly reactive ethylen-immonium derivative alkylates DNA and other biomolecules and causes the cytotoxic effect. 

Some of their derivatives have been used as antiviral drugs. Due to their flexible chemistry, they can be exploited to design drug delivery systems and in molecular nanotechnology. In such systems, they can act as a central lipophilic core and different parts like targeting segments, linkers, spacers, or therapeutic agents can be attached to the said central nucleus. Their central core can be functionalized by peptidic and nucleic acid sequences and also by numerous important biomolecules. 

In 1994, thiols were firstly used as stabilizers of gold nanoparticles [6a]. Thiols form monolayer on gold surface [18] and highly stable nanoparticles could be obtained. Purification of nanoparticles can be carried out, which makes chemical method of metal nanoparticles a real process for nanomaterial preparation. Various thiol derivatives have been used to functionalize metal nanoparticles [6b, 19]. Cationic and anionic thiol compounds were used to obtain hydrosols of metal nanoparticles. Quaternary ammonium-thiol compounds make the nanoparticle surface highly positively charged [20]. In such cases, cationic nanoparticles were densely adsorbed onto oppositely charged surfaces. DNA or other biomolecule-attached gold nanoparticles have been proposed for biosensors [21]. 

Recent developments in DNA/RNA chemical synthesis have allowed us to attach some functional groups covalently to nucleic acids, thus permitting the introduction of a functionality or properties not normally present in the native biomolecule The use of non-nucleosidic linkers is probably the most popular approach for the 5 -terminal modification of chemically synthesized nucleic acid oligonucleotides and a number of such linkers are commercially available. The linker shown in Fig. 2 is designed as a phosphoramidate derivative so that it can be incorporated into the 5 -terminus of the sequence as the last... 

Liu S (2005) 6-Hydrazinonicotinamide Derivatives as Bifunctional Coupling Agents for "mTc-Labeling of Small Biomolecules. 252 117-153 Liu S, Robinson SP, Edwards DS (2005) Radiolabeled Integrin avp Antagonists as Radio-pharmaceuticals for Tumor Radiotherapy. 252 193-216 Liu XY (2005) Gelation with Small Molecules from Formation Mechanism to Nanostructure Architecture. 256 1-37... 

As with conductivity measurements, methods and results of theoretical treatments of CT in DNA have varied significantly. Mechanisms invoking hopping, tunneling, superexchange, or even band delocalization have been proposed to explain CT processes in DNA (please refer to other reviews in this text). Significantly, many calculations predicted that the distance dependence of CT in DNA should be comparable to that observed in the a-systems of proteins [26]. This prediction has not been realized experimentally. The dichotomy between theory and experiment may be related to the fact that many early studies gave insufficient consideration to the unique properties of the DNA molecule. Consequently, CT models derived for typical conductors, or even those based on other biomolecules such as proteins, were not adequate for DNA. 

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