. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THE STRUCTURE OF A FISH BRAIN ANP 281 Table I imino acid compositions of synthetic ANP Aminoacid Ratios Crude found Pure found Theor. Glycine Leucine 6 3 Arginine Methionine .60 2 1 Phenylalanine Serine .93 .85 1 2 Aspartic acid Isoleucine .99 T 1 Lysine Cystine (1/2) + .83 1 2 + : Present, hut not quantified. by weight. The peptide was removed from the resin with anhydrous HF/anisole (9/1) at 0°C for 1 h. The peptide was extracted with 10% acetic acid/wat
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THE STRUCTURE OF A FISH BRAIN ANP 281 Table I imino acid compositions of synthetic ANP Aminoacid Ratios Crude found Pure found Theor. Glycine Leucine 6 3 Arginine Methionine .60 2 1 Phenylalanine Serine .93 .85 1 2 Aspartic acid Isoleucine .99 T 1 Lysine Cystine (1/2) + .83 1 2 + : Present, hut not quantified. by weight. The peptide was removed from the resin with anhydrous HF/anisole (9/1) at 0°C for 1 h. The peptide was extracted with 10% acetic acid/water and yielded 118 mg after lyophilization. The amino acid analysis is shown in Table I (crude). The formyl group (from the indole ring of Trp) was removed and the disulfide bond formed by bubbling air through a 5 X 10~5 M solution of peptide in .5 M ammonium bicarbonate, which had been adjusted to pH with ammonium hydroxide. The pep- tide was purified by HPLC and quantitated by amino acid analysis (Table I, pure). Vasorelaxant activity Rings cut from the ventral aorta of toadfish (Opsamts beta) were suspended in physiological saline and their tension recorded. Peptide solutions were added and the drop in tension recorded (Evans et ai, 1989). Results Only one major peak of immunoreactivity showed up on the first HPLC fractionation (Fig. 1), but often there were two peaks at the second step separated by about 2 min in elution time (Fig. 2A). We suspected that the ear- lier-eluting peak might be an oxidation product of the second, and confirmed this by oxidizing the later peak, thereby shifting its retention time to that of the earlier peak (Fig. 2B). This shift is sufficient to move the ANP- like peak out from under the impurities remaining at the second step. We judged the peak to be pure enough for sequencing after the third step. Thus, deliberate oxida- tion allows purification of the peptide in fewer steps than would otherwise be required. From about 1500 brains (50 g t
Size: 1701px × 1470px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
