Cholecystokinin octapeptides purified from chinchilla and chicken brains

Cholecystokinin octapeptides (CCK8's) have been purified from methanol extracts of 30 chinchilla and 50 chicken brains containing 9.3 nmol and 8.5 nmol of the peptides respectively. Immunoreactive CCK was concentrated on a DEAE trisacryl column and purification effected by two successive HPLC steps. The peptides were each shown to have a sulfated tyrosine. The sequences of the two peptides are compared with the corresponding CCK8's of pig and guinea pig (GP). Chinchilla & GP: D Y V G W M D F; Chicken & pig: D Y M G W M D F. Since chinchilla insulin resembles other mammalian insulins more than does GP insulin, it is of particular interest that the CCK8's of these two species are identical and raises the question as to whether other brain-gut peptides of the chinchilla, which is a New World mammal as is the GP, would resemble those of the GP or the corresponding peptides of Old World mammals.