Günter Kegel

Amino acid sequence of the crustacean hyperglycemic hormone (CHH) from the shore crab, Carcinus maenas.

Crustacean hyperglycemic hormone (CHH) was isolated from sinus glands of Carcinus maenas, and its primary structure was determined by manual microsequencing, using the DABITC‐PITC double‐coupling method. The neurohormone consists of 72 amino acid residues (8524 Da). Three disulfide bridges are present and both the N‐ and C‐terminus are blocked. CHH does not show significant sequence homology to any known peptide hormone or protein.

Amino acid sequence of crustacean hyperglycemic hormone (CHH) from the crayfish, Orconectes limousus: Emergence of a novel neuropeptide family

The primary structure of the major form of CHH from sinus glands of the crayfish, Orconectes limosus, was determined by manual Edman microsequencing. It is a 72-residue peptide with a calculated Mr of 8400 Da. In the number of residues, it is identical to the CHH of Carcinus maenas and very similar to MIH (moult inhibiting hormone) of Homarus americanus. All three peptides have pGlu as N-terminus in common, and Val-NH2 is the C-terminal residue in Orconectes and Carcinus CHH. Six Cys residues occupy identical position in the three peptides. There is a 61% sequence identity with Carcinus CHH, and an 81% identity with Homarus MIH.

The role of the Y-organ and cephalic gland in ecdysteroid production and the control of molting in the crayfish,Orconectes limosus

SummaryThe production of ecdysteroids (monitored by RIA) by Y-organs and cephalic glands in vitro was measured and hemolymph ecdysteroid levels were determined in the crayfish,Orconectes limosus, both after eyestalk ablation and as a function of time during natural premolt. Y-organ synthesis of ecdysteroid increased in parallel with a rise in hemolymph ecdysteroid concentrations under both conditions, peaking in substage D2 of premolt. Y-organ ecdysteroid output after eyestalk ablation was 3–4 times higher. Thus, removal of the inhibiting system of the eyestalk effectively removes not only the principal control but also any modulation of ecdysteroid secretion by the Y-organs. Ecdysteroid levels remained low in Y-organ-ectomized crayfish, although premolt was initiated in some animals. The cephalic gland does not appear to contribute to the regulation of molting inOrconectes limosus. The Y-organs, on the other hand, are a principal source of ecdysteroids which regulate the major synthetic activities of premolt.

Isolation and characterization of red-pigment-concentrating hormone (RPCH) from six crustacean species

SummaryRed-pigment-concentrating hormone (RPCH) has been isolated from nerve tissue of six decapod crustaccan species. The primary structure of three of the six hormones, i.e., those ofCancer magister, Carcinus maenas andOrconectes limosus, was determined by manual microsequencing as: pELNFSPGW-NH2. This sequence is identical to that of RPCH fromPandalus borealis, the only previously known sequence of a crustacean RPCH. The other three hormones fromLiocarcinus puber, Nephrops norvegicus, andPacifastacus leniusculus could not be characterized completely. However, amino acid compositions, the presence of N-terminal pGlu, and the blocked N-terminal ends are in accordance with the primary structure established for the other three RPCHs. We suggest that all six peptides have the same amino acid sequence. These results indicate that RPCH, which is likely to be related to the peptides of the AKH family in insects, is highly conserved among crustacean species. This is in remarkable contrast to the high degree of molecular evolution exemplified by the many different AKH-like peptides among insect species.

The hyperglycemic neuropeptide of the terrestrial isopod, Porcellio dilatatus. I. Isolation and characterization

From isolated sinus glands of Porcellio dilatatus, a hyperglycemic neuropeptide (CHH) was purified by means of a single, two-step purification procedure which consisted of gel chromatography on Sephadex G-50, followed by high-performance liquid chromatography. The 5800- to 6100-Da peptide contains 50-52 amino acids residues. The amino acid composition is (Pro, Ile)1; His1-2; (Thr, Ser, Gly, Met, Tyr)2; (Val, Phe, Lys)3; (Ala, 1/2Cys, Leu, Arg)4; Glx5; Asx7; Trp, n.d. The amino acid composition differs from that of two decapod CHHs analyzed thus far. The N-terminus is blocked. The neuropeptide exhibits little or no interspecific hyperglycemic effect in the brachyuran, Uca pugilator, and its cross-reactivity and potency in the RIA for Carcinus-CHH is very low.

Structure-activity relationships of the crustacean myotropic neuropeptide orcokinin.

Orcokinin (OK, NFDEIDRSGFGFN) was recently identified from the crayfish, Orconectes limosus, as a potent hindgut-stimulating factor (14). To assess the importance of structural features of the peptide involved in effective ligand-receptor interactions, synthetic analogues of orcokinin were tested in the hindgut bioassay. Tests with N- and C-terminal-truncated analogues and the C-terminal-amidated analogue (OK-NH2) demonstrate that changes at the C-terminus interfere less with biological activity than changes at the N-terminus. Removal of more than one amino acid at the N-terminus resulted in a complete loss of activity, whereas the C-terminal deletion of three amino acids still produced an analogue with full intrinsic activity but with a drastic shift in threshold concentration of activity from 1 x 10(-10) to 1 x 10(-7) M. Deletion of four amino acids at the C-terminus resulted in a completely inactive analogue. The C-terminal hydroxyl group does not seem to be important because amidation (OK-NH2) resulted in almost no loss of activity. Replacing Arg7 with Ala produced an analogue almost equipotent to orcokinin. Replacement of Phe2 by Tyr resulted in considerable loss of activity. An important role of Phe2 is further suggested by the steep drop of activity after removal of this residue in the N-terminal-deleted analogues.

Lysine derivatives in crustacean calmodulins: a comparative study on five decapod species

Abstract 1. 1. Calmodulins from muscle tissue of five decapod crustacean species, Astacus leptodactylus, Homarus americanus, Nephrops norvegicus, Carcinus maenas and Palaemon serratus, representing the suborders Natantia and Reptantia were purified and characterized. 2. 2. Molecular weight, pI, and their potency to activate phosphodiesterase are identical to that of calmodulin from bovine brain. 3. 3. The amino acid composition of the purified proteins was determined to evaluate the possibility of phylogenetic relationship between TML-free and TML-containing calmodulins. 4. 4. Four of the purified calmodulins contain a mixture of TML and DML adding to mol per mol protein, Astacus leptodactylus calmodulin only contains 0.1 mol TML.