Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 1 of 1
Full-Text Articles in Internal Medicine
Plasma Native And Peptidase-Derivable Met-Enkephalin Responses To Restraint Stress In Rats. Adaptation To Repeated Restraint, K. Pierzchala, G. R. Van Loon
Plasma Native And Peptidase-Derivable Met-Enkephalin Responses To Restraint Stress In Rats. Adaptation To Repeated Restraint, K. Pierzchala, G. R. Van Loon
Internal Medicine Faculty Publications
Met-enkephalin and related proenkephalin A-derived peptides circulate in plasma at picomolar concentration as free, native pentapeptide and at nanomolar concentration in cryptic forms. We have optimized conditions for measurement of immunoreactive Met-enkephalin in plasma and for generation by trypsin and carboxypeptidase B of much greater amounts of total peptidase-derivable Met-enkephalin in plasma of rats, dogs, and humans. Free Met-enkephalin (11 pM) is constituted by native pentapeptide and its sulfoxide. Characterization of plasma total Met-enkephalin derived by peptidic hydrolysis revealed a small amount (38 pM) of Met-enkephalin associated with peptides of molecular mass less than 30,000 D, and probably derived from …