A neurosecretory hyperglycemic hormone from the sinus gland of the Mexican crayfish Procambarus bouvieri (Ortmann)--II. Structural comparison of two isoforms of the hormone.

1. The hyperglycemic activity of a crude extract of Procambarus bouvieri (Ortmann) sinus glands was resolved into two UV-absorbing peaks by means of a single step of reverse-phase high performance liquid chromatography (RP-HPLC) on a mu-Bondapak-Phenyl column. These peaks have been designated Crustacean Hyperglycemic Hormones CHH-B and CHH-C in the order of elution. 2. The ratio CHH-B/CHH-C was approximately 3:1, both in area under the curve and in protein content. 3. A structural comparison of the two isoforms of the CHH showed a substantial homology manifested in molecular weight (6000-6200), pI (4.79), number of residues (52-53), number of cysteines (4), number of acid residues, including their amides (12), number of basic residues (8), missing amino acids (methionine, histidine and tryptophane), amino end (blocked) and carboxyl end (isoleucine). 4. The only clear difference between the two isoforms of the CHH is their degree of hydrophobicity which might be due to minor differences in the number of neutral hydrophobic residues and/or postranslational modifications of the type amidation/deamidation of acid residues which cannot be detected in acid hydrolysates.