[Synthesis of human [11-leucine]minigastrin I--II. Purification of the synthetic tridecapeptide amide and isolation of a side-product (author's transl)].

The preparation of the pure 11-leucine analogue of human minigastrin I, a linear tridecapeptidaemide with full "gastrin activity", from the crude synthetic material obtained after deblocking of the overall protected tridecapeptide amide derivative by means of trifluoroacetic acid, is achieved by ion-exchange chromatography on DEAE-Sephadex A-25 and subsequent partition chromatography on Sephadex G-25. The isolation of a synthetic side-product and its identification as human [10-(Nin-tert-butyl-tryptophan),11-leucine]minigastrin I by means of spectroscopic (UV, fluorescence, 1H-NMR, MS), enzymatic and chromatographic methods is described. The pure tridecapeptide amides human [Leu11]minigastrin I and human [Trp(1'-But)10,Leu11]minigastrin I are isolated in overall yields of 37.4% and 4.6%, respectively (mol-% with regard to the overall protected tridecapeptide amide derivative).