The invention relates to a process for preparing a serine-protease inhibitor. According to the invention, the process consists in subjecting ground and delipidated water melon (Citrullus vulgaris) seeds to aqueous extraction in acetate buffer 0.1M having a pH value of 5 and to fractional precipitation of the supernatant with ethyl alcohol, in two stages: a first stage during which the extract is treated, at the ambient temperature, with an equal amount of ethanol, for 1 h, and the precipitate is removed, and a second stage during which the filtrate obtained in the first stage is treated at a temperature of -20°C with 4 volumes of ethanol, then the resulting precipitate is solubilized in distilled water and brought in an equal volume of acetate buffer 0.1 M, pH 5.5, is purified in a column pre-balanced with acetate buffer and eluated with a NaCl solution in a 0...0.6 M concentration gradient in the same buffer, and the fractions brought to a pH value of 7.5 with a 2 M Tris solution are applied onto a column filled with immobilized tripsine pre-balanced with Tris-HCl buffer, pH 7.5, after which the serine-protease inhibitor is desorbed by eluation with glycocol-HCl buffer, pH 2.8, with 0...0.3 M concentration gradient in equal volumes, to finally result in a product with a specific activity of 9122 IU/mg of protein.Invenţia se referă la un procedeu de obţinere a unui inhibitor serin-proteazic. Procedeul conform invenţiei constă din aceea că seminţele de pepene verde () măcinate şi delipidizate, sunt supuse extracţiei apoase în tampon acetat 0,1M cuH 5 şi precipitare fracţionată a supernatantului cu alcool etilic în două trepte: o primă treaptă în care extractul se tratează timp de 1 h, la temperatura camerei, cu un volum egal de etanol, cu îndepărtarea precipitatului, şi o a doua treaptă în care filtratul din prima treaptă se tratează la -20°C cu 4 volume de etanol, după care precipitatul rezultat se solubilizează în apă distilată şi se aduce într-un volum egal de
