Changes and characteristics of the crustacean hyperglycemic hormone (CHH material) in Palaemon serratus pennant (crustacea, decapoda, natantia) during the different steps of the purification

Amino acid sequences and activities of multiple hyperglycemic hormones from the Kuruma prawn, Penaeus japonicus

By means of a single-step reversed-phase HPLC, six CHH family peptides were isolated from sinus gland extracts of the kuruma prawn, Penaeus japonicus. Five of these peptides (Pej-SGP-I, -II, -III, -V, and -VI) expressed hyperglycemic activity and were considered to be the hyperglycemic hormones of this prawn. The amino acid sequences of the five peptides were determined (the amino acid sequence of Pej-SGP-III had been previously determined), revealing that all consisted of 72 amino acid residues with a free amino-terminus and an amidated carboxyl-terminus. They showed considerable sequence similarity to one another, but much less similarity to Pej-SGP-IV with molt-inhibiting activity, the sequence of which had also been determined previously. Examination of the dose-response relationship of these peptides showed that they were equally potent but had different efficacies, which were in the order of Pej-SGP-V, -VI > -III, -I > -II, corresponding well with their sequence characteristics.

Neuropeptides from the sinus gland of the lobster Homarus americanus: Characterization of hyperglycemic peptides

In order to characterize hyperglycemic peptides from the sinus gland of the lobster, Homarus americanus, a bioassay was developed with juvenile H. gammarus. This assay was used for determining the hyperglycemic activity of peptides perified by reversed-phase high-performance liquid-chromatography, from acidic extracts of sinus gland. The major peptides are eluted in three sets of two peptides. Among them, two pairs show hyperglycemic activity when assayed on lobster; when assayed on crayfish, three peptides are active. The less hydrophobic pair consists of basic peptides (pI: 8.7), with a MW of 8633 Da., determined by fast-atom bombardment mass spectrometry. The most hydrophobic pair consists of acid peptides (pI: 5.0), with a MW of 8577 Da. Amino acid composition of the hyperglycemic peptides shows strong homologies within each pair.