Porphyrins biomolecules

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). 

Much effort has also been directed toward mimicking electron transfer on natural photosynthetic systems. Recently, the group of Harada has been able to prepare monoclonal antibodies against metallo porphyrins and show that the biological edifice can control photoinduced electron transfer from the porphyrin to organic acceptor molecules in solution. As it was important to design a biomolecule able to accommodate not only the metalloporphyrin unit but also organic substrates, Harada recently used a hexacoordinated phosphorus... 

The applications of visible fluorescent immunosensors described are all susceptible to large interferences from biomolecules such as bilirubin and porphyrins. A more comprehensive review of immunosensors has been published by Robinson.(10S) The spectral interferences associated with visible fluorophores have prompted the design of an NIR optical immunosensor techniques with high sensitivity and low interference. 

In addition to their role as the building blocks of proteins, amino acids are precursors of many specialized biomolecules, including hormones, coenzymes, nucleotides, alkaloids, cell wall polymers, porphyrins, antibiotics, pigments, and neurotransmitters. We describe here the pathways to a number of these amino acid derivatives. 

Many important biomolecules are derived from amino acids. Glycine is a precursor of porphyrins. Degradation of iron-porphyrin (heme) generates bilirubin, which is converted to bile pigments, with several physiological functions. 

In addition to serving in their role as precursors of proteins, amino acids are essential precursors of other biomolecules, of which we discuss two examples The synthesis of porphyrin and the synthesis of glutathione. 

Metal complexes like lanthanide chelates (mainly europium or terbium), ruthenium phenanthrolines or bipyridyls, and platinum porphyrins can be used as fluorescent labels for biomolecules. Their long decay times are perfectly suited for a detection by time-resolved imaging, and the labeled target molecules can be used for the determination of intracellular recognition processes or for the screening of DNA and protein arrays. Ratiometric lifetime-based imaging methods in combination with sophisticated data acquisition and evaluation tools can substantially contribute to the development... 

The porphyrin motif, four pyrrole rings linked by carbon atoms to give a planar cyclic compound, is found in many biomolecules. It is present in haemoglobin and myoglobin and its derivatives are also at the core of vitamin B12, hydrogenases, cytochrome c, the chlorophyll photosystem and similar essential proteins. 

Another blchromophorlc system, studied as a model for biomolecules, consists of two covalently linked metal porphyrins [13] (55). 

This composite satellite image displays areas on the surface of the Earth where chlorophyll-bearing plants are located. Chlorophyll, which is one of nature s most important biomolecules, is a member of a class of compounds called porphyrins. This Glass also includes hemoglobin and cytochrome c, which is discussed in Feature 19-1. Many analytical techniques have been used to measure the chemical and physical properties of chlorophyll to explore Its role in photosynthesis. The redox titration of chlorophyll with other standard redox couples reveals the oxidation/ reduction properties of the molecule that help explain the photophysics of the complex process that green plants use to oxidize water to molecular oxygen. 

Recently, we have also used VCD and a combination of VCD and ECD to study the non-covalent interactions between two groups of important biomolecules, i.e. biopolymers - polypeptide and DNA - and cationic and anionic porphyrins [34-36]. 

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