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Human Leukocyte Migration Inhibitory Factor (LIF)
Author(s) -
BENDTZEN K.
Publication year - 1977
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1977.tb00328.x
Subject(s) - pmsf , serine , chemistry , phenylmethylsulfonyl fluoride , biochemistry , esterase , serine protease , diisopropyl fluorophosphate , trypsin , enzyme , kunitz sti protease inhibitor , leukemia inhibitory factor , protease , embryonic stem cell , gene
Previously reported experiments suggested that an esterase or a protease, or both, might participate in the expression of human leukocyte migration inhibitory factor (LIF). To clarify this further, a wide variety of simple esters were tested for the ability to protect LIF against inactivation by the serine esterase inhibitor phenylmethylsulfonyl fluoride (PMSF). α‐ N ‐benzoyl‐L‐arginine ethylester (BAEE), a typical trypsin substrate, and bis‐ p ‐nitrophenyl phosphate (BNPP); a phosphodiester, were the only esters capable of retaining LIF activity in the presence of PMSF. Agents chemically closely related to these esters were inactive. Moreover, the protection afforded by BAEE and BNPP was the kind that would be anticipated if the esters and irreversible inhibitor competed for the same site on LIF. BAEE and BNPP also protected against inactivation by di‐isopropyl‐fluorophosphate (DFP), another irreversible serine esterase inhibitor. In addition, LIF‐treated leukocytes partly escaped migration inhibition in the presence of BAEE and BNPP, respectively. These results indicate that human LIF contains a serine residue necessary for lymphokine activity. It is still not proved, however, that LIF as an enzyme is capable of hydrolyzing BAEE and BNPP, although it seems highly possible. The substrate specificities of a putative LIF enzyme are discussed on the basis of the chemical structure of BAEE and BNPP.