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Isolation of pyroglutamic acid from hypothalamic tissue and significance of its inhibition of prolactin release

1978; Elsevier BV; Volume: 81; Issue: 2 Linguagem: Inglês

10.1016/0006-291x(78)91590-5

1090-2104

Yiu-Kuen Lam, Ronald Knudsen, Karl Folkers, Willi Frick, G. Doyle Daves, Douglas F. Barofsky, Cyril Y. Bowers,

Metabolism, Diabetes, and Cancer

Extensive fractionation of extractives of porcine hypothalamic tissue was scaled-up with the guidance of bioassays including the inhibition of prolactin release, because previously ca. <100 ng of fraction, which could have been essentially pure, was active at ca. <5 ng, to inhibit prolactin. Ultimately, an active entity was isolated and characterized as pyroglutamic acid. This amino acid was newly found to inhibit the release of prolactin at μg-levels. The presence and activity of pyroglumatic acid during fractionation for the presumed authentic prolactin inhibiting factor (PIF) was an unknown difficulty, which now may interest others working with PIF extracts and fractions. This difficulty may now be circumvented.