Open AccessThe isolation, purification and amino‐acid sequence of insulin from the teleost fish Cottus scorpius (daddy sculpin)
Author(s) -
CUTFIELD John F.,
CUTFIELD Susan M.,
CARNE Alan,
EMDIN Stefan O.,
FALKMER Sture
Publication year - 1986
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1986.tb09728.x
Subject(s) - sculpin , insulin , cottus , biology , peptide sequence , amino acid , islet , biochemistry , pancreatic islets , chemistry , endocrinology , fish <actinopterygii> , fishery , gene
Insulin from the principal islets of the teleost fish, Cottus scorpius (daddy sculpin), has been isolated and sequenced. Purification involved acid/alcohol extraction, gel filtration, and reverse‐phase high‐performance liquid chromatography to yield nearly 1 mg pure insulin/g wet weight islet tissue. Biological potency was estimated as 40% compared to porcine insulin. The sculpin insulin crystallised in the absence of zinc ions although zinc is known to be present in the islets in significant amounts. Two other hormones, glucagon and pancreatic polypeptide, were copurified with the insulin, and an N‐terminal sequence for pancreatic polypeptide was determined. The primary structure of sculpin insulin shows a number of sequence changes unique so far amongst teleost fish. These changes occur at A14 (Arg), A15 (Val), and B2 (Asp). The B chain contains 29 amino acids and there is no N‐terminal extension as seen with several other fish. Presumably as a result of the amino acid substitutions, sculpin insulin does not redily form crystals containing zinc‐insulin hexamers, despite the presence of the coordinating B10 His.