Characterization of dopuin, a polypeptide with special residue distributions.
A 62-residue polypeptide, dopuin, has been isolated from pig small intestine. It is distinguished by an N-terminal part with a high content of proline (7 in a 26-residue segment), a C-terminal part with a high proportion of histidine (3 in a 9-residue segment), and six half-cystine residues in three intrachain disulphide bridges (connecting positions 22-25, 23-54 and 35-44). The Cys and Pro distributions suggest a tight and special conformation. In contrast to PEC-60 and somatostatin, it has no established inhibitory effect on insulin secretion. At 10 nM concentration, a weak inhibitory tendency is less than half of that of the other two peptides. Like gastrointestinal trefoil peptides, dopuin has three disulphide bridges, Ala-Pro segments, and many charged residues, but they are differently distributed and dopuin belongs to a separate, apparently novel family. However, dopuin is similar to a peptide corresponding to an expressed-sequence-tag cDNA of human fetal liver and spleen, establishing the nature of the mature form of the product of this cDNA, and showing a general tissue, age, and species distribution of this peptide. A truncated form of vimentin, composed of its C-terminal 37 residues, vimentin-C37, was also purified and structurally characterized. These two peptides increase the complexity of known intestinal polypeptides and at least dopuin has properties compatible with specific biofunctions.
Chen
Z W
ZW
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Bergman
T
T
Ostenson
C G
CG
Efendic
S
S
Mutt
V
V
Jörnvall
H
H
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000737:chemistry; D005768:Gastrointestinal Hormones / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D004763:Glucagon-Like Peptides; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007421:Intestine, Small / Q000737:chemistry*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000196:embryology / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013154:Spleen / Q000196:embryology / Q000378:metabolism; D013552:Swine; D014746:Vimentin / Q000737:chemistry
D004220:Disulfides; D005768:Gastrointestinal Hormones; D007328:Insulin; D010446:Peptide Fragments; D010455:Peptides; D014746:Vimentin; C109197:dopuin; D004763:Glucagon-Like Peptides; C015236:glucagon-like-immunoreactivity