striatal extracts of guinea pigs , rats , and cattle were found to contain two large proteins ( greater than 40,000 and greater than 100,000 daltons ) that on treatment with trypsin yield opioid peptides differing chromatographically from the opioid nonapeptide generated by trypsin digestion of endorphins , beta-lipotropin , or pro-opiocortin .
C0205753
opioid peptides
C0014242
endorphins