Biologically relevant unit

Some deposited structures in the PDB, such as binding proteins, may only represent part of the story. The biologically relevant unit may, in fact, be an aggregate of more than one chemically distinct structural domain the crystal structure in the PDB may represent only one of these domains. An example is the set of matrix metalloproteinases (MMP) structures. Some MMPs are bound to hemopoxin moi-... 

The reaction of [Pt(dien)Cl]Cl with S-adenosyl-L-homocysteine (SAH, a biologically relevant molecule, as it is the coproduct of the methyl transfer reaction by S-adenosyl-L-methionine see Fig. 15) results in a mixture of complexes (193), i.e., the mononuclear complex (1) [Pt(dien)(SAH-S)]2+, with platination of SAH at the sulfur atom, the mononuclear complex (2) [Pt(dien)(SAH-ADJ+, which has a Pt(dien)2+ unit coordinated to the amino group of the homocysteine unit, and the dinuclear complex (3) [ Pt(dien) 2(SAH-S,AD]3+, which has a Pt(dien)2+ unit coordinated to the sulfur atom as well as a Pt(dien)2+... 

The palladium-catalyzed formation of diarylamines has been used in several contexts to form molecules with biological relevance. The ability to prepare haloarenes selectively by an ortho-metallation halogenation sequence allows for the selective delivery of an amino group to a substituted aromatic structure. Snieckus has used directed metallation to form aryl halides that were subsequently reacted with anilines to prepare diarylamines (Eq. 34)) [156]. Frost and Mendon a have reported an iterative strategy to prepare (by palladium-catalyzed chemistry) amides and sulfonamides that may act as peptidomimetics. Diarylamine units are constructed using the DPPF-ligated palladium catalysts, and the products are then acylated or sulfo-nated with 4-bromo benzoyl or arylsulfonyl chlorides [157]. 

Iron-sulphur clusters constitute integral parts of several natural structures occurring in a large family of biologically relevant metalloproteins. The [Fe-S] units... 

One of the most commonly used type of broadband detectors for measurement of solar UVR, the so-called Robertson-Berger type detector [12,13], has a spectral sensitivity which is adapted to the standardized erythema action spectrum of the human skin [14]. It has the maximum of its sensitivity around 297 nm, then sensitivity decreases steeply to about 320 nm and in the UV-A range the sensitivity is about 1000 times smaller than at the maximum in the UV-B. Thus these detectors give a direct measure for the biologically relevant irradiance. However, as no one available detector has a spectral sensitivity perfectly matched with the erythema action spectrum, corrections are necessary to get a standardized output from these instruments. These corrections depend on the variation of the solar spectrum, mainly correlated with solar zenith angle and with total atmospheric ozone content, and are specific to an individual instrument. This conversion from detector based units into absolutely defined erythemally weighted units may not be necessary if relative variations of UVR are observed over longer time scales at one station only and no absolute comparison is made with results from other detectors. 

Three new azamacrocyclic-cyclophane, hybrid receptors have been created based on the incorporation of either 1,4,7,10-tetraazacyclododecane or 1,4,7-triazacyclononane units tethered by a short amidic spacer to an electron donor and a //-bonding crown ether. These direceptors are designed to act as hosts for biologically relevant guests <05JOC115>. 

---