PubMed · 5525771
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R O Brady. 1970. Further developments in studies in sphingolipidoses: "missing enzymes".. https://pubmed.ncbi.nlm.nih.gov/5525771/
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High-resolution spectra of the CN B2 summation operator +-X2 summation operator + (0,0) band at 390 nanometers yield isotopic ratios for comets C/1995 O1 (Hale-Bopp) and C/2000 WM1 (LINEAR) as follows: 165 +/- 40 and 115 +/- 20 for 12C/13C, 140 +/- 35 and 140 +/- 30 for 14N/15N. Our N isotopic measurements are lower than the terrestrial 14N/15N = 272 and the ratio for Hale-Bopp from measurements of HCN, the presumed parent species of CN. This isotopic anomaly suggests the existence of other parent(s) of CN, with an even lower N isotopic ratio. Organic compounds like those found in interplanetary dust particles are good candidates.
The lipophilic beta-lactone, lipstatin, inhibits pancreatic lipase and has been shown earlier to be biosynthesized by Claisen condensation of two fatty acid moieties. We present data from incorporation experiments with [U-13C6]leucine showing that a branched chain analogue of lipstatin is biosynthesized from leucine.
The pK(A) values of (4RS)-[4-carboxy-5,8,11-tris(carboxymethyl)-1-phenyl-2-oxa-5,8,11-triazatridecan-13-oic acid] (BOPTA), a polyprotic molecule whose gadolinium complex is an important magnetic resonance imaging contrast agent for clinical use, have been determined in water, in physiologic solution (PS), in serum (S), and in cerebrospinal fluid (CSF), by means of 13C nuclear magnetic resonance spectroscopy data processed by a dedicated software package called DISCO. The aim of this study was to supply the BOPTA pK(A) values in media very similar to the in vivo environment and, consequently, to get a picture of the in vivo behavior of its Gd complex, whose thermodynamic stability is directly linked to the pK(A) values. The pK(A) values appeared to be almost equal both in D(2)O and in PS, while pK(1) and pK(5) values in CSF differ a little. In S, only pK(2) and pK(3) were calculated due to the narrow pH range used for data collection. However, these pK(A) values were found equal to those in the other media. These results represent the first direct spectroscopic evidence of a substantial invariability of BOPTA behavior in different media and they justify the extrapolation to biological fluids of the data obtained in water. The values also confirmed the high-quality performance of DISCO in calculating pK(A) values of polyprotic molecules in complex media.