Molecular equivalence numbers Subject

Linear hydrocarbon radicals have been the subject of intensive laboratory spectroscopic and radio-astronomical research since the early 1980s. In recent years, a considerable number of rotational spectroscopic studies of medium to longer hydrocarbon chains such as C5H, CeH, CgH, and ChH have been carried out using a pulsed molecular beam FTMW spectrometer. The high resolution offered by such a spectrometer allowed the detection of the hyperfine sphtting of rotational transitions. These measurements improved fine and hyperfine coupling constants and provided rest frequencies with accuracies better than 0.30 km s in equivalent radial velocity up to 50 GHz. Indeed, some of the small C H radicals with n < 9 have subsequently been detected in space, in molecular cloud cores, and in certain circumstellar shells. These hydrocarbon chains are among the most abundant reactive space molecules known. 

The primary amino acid sequence of rabbit muscle aldolase has been determined [27]. The molecular weight of the protein is 160000, and it has 4 equivalent subunits each bearing an active site. Some aldolases are found as tetramers of a and subunits which differ only by the conversion of Asn 358 to an aspartate residue. Because this enzyme is essential to glycolysis, because it is readily available, and because it is mechanistically interesting it has been the subject of a large number of studies. These include determinations of active-site residues, order of substrate addition, stereochemistry, and chemical mechanism which will be integrated below in an attempt to generate a picture of the active-site structure. 

When a premixed solution of DBA-OC10,10 with hexakis(phenylethynyl)benzene HPEB (about 2.5 equivalent excess) whose molecular size would fit the pore size formed on the surface by DBA-OC10,10 was subjected to STM observations, two types of pores were visualized one containing a clear star-shaped feature ascribed to immobilized HPEB and the other with a fuzzy feature, most likely due to mobile HPEB (Figure 6.12). In addition, a small number of vacant pores were also observed. 

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