. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PIGMENT-DISPERSING HORMONE 139 80 60 40 X o Q. 20 0. 20 30 40 50 60 70 80 Fraction Number FIGURE 3. Partition chromatography on Sephadex G-50 superfine of the combined major PDH zones obtained by cation-exchange chromatography (fractions 26-33 in Fig. 2) from kg of eyestalk powder. Column: X cm; eluant (without TDE): organic phase of n-butanol-HOAc-HjO, 4:1:5, v/v; flow rate of ml/h, fraction size ml; Vm, volume of mobile phase, ml; V,, total volume of column, 156 ml. Bioassay: 5 jul aliquots from
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PIGMENT-DISPERSING HORMONE 139 80 60 40 X o Q. 20 0. 20 30 40 50 60 70 80 Fraction Number FIGURE 3. Partition chromatography on Sephadex G-50 superfine of the combined major PDH zones obtained by cation-exchange chromatography (fractions 26-33 in Fig. 2) from kg of eyestalk powder. Column: X cm; eluant (without TDE): organic phase of n-butanol-HOAc-HjO, 4:1:5, v/v; flow rate of ml/h, fraction size ml; Vm, volume of mobile phase, ml; V,, total volume of column, 156 ml. Bioassay: 5 jul aliquots from alternate fractions were lyophilized, the residues dissolved in ml saline, and 50 n\ injected into each of 3 test Llca. The PDH activity is expressed as Standard Integrated Response values, as defined by Fingerman el al. (1967). regarded as the carboxyl-terminal residue. Further characterization of this residue, by HPLC analysis of the products of dilute acid cleavage, showed that the carboxyl- terminal Ala occurs in an amidated form. Thus the primary structure of the purified PDH from Cancer magister is: Asn-Ser-Glu-Leu-Ile-Asn-Ser-Ile-Leu-Gly-Leu-Pro-Lys- Val-Met-Asn-Asp-Ala-NH2. A synthetic preparation of this octadecapeptide (Rao el al., 1985) and the purified native PDH from Cancer magister were equipotent in assays for melanophore pigment dispersion in destalked Uca pugilator (Fig. 6). DISCUSSION The present study shows that the PDH purified from eyestalks of Cancer magister is structurally identical to the major form of PDH in eyestalks of Uca pugilator (Rao et al, 1985). For convenience in discussion this octadecapeptide will be hereafter called /3-PDH, whereas the first characterized PDH (=DRPH) from Pandalus borealis (Fernlund, 1976) will be designated as «-PDH. The amino acid sequences of the two PDHs show identity, the differences being found at positions 3, 4, 11, 13, 16, and 17, as shown below: a-PDH: Asn-Ser-G3ly-Met-Ile-Asn-Ser-Ile-Leu-Gly-Ile-Pro-A
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
