Resumen

ROJAS, Evelin et al. GMP Isolation and Yield by Whey Precipitation With Trichloroacetic Acid. Rev. Cient. (Maracaibo) [online]. 2009, vol.19, n.3, pp.295-302. ISSN 0798-2259.

During cheese manufacturing k-casein is hydrolyzed by rennin (Quimosine E.C.3.4.23.4) on peptidic bond Fen¹⁰⁵- Met¹⁰⁶ releasing two fractions: para-k-casein and glycomacropeptide (GMP). GMP shows a particular chemical structure in which ramified lateral chain aminoacids prevail, without aromatics aminoacids, but with carbohydrates short chains linked to some threonine residues; because of this, a variety of biological activities have been attributed to molecule. It has been considered that in Venezuela, 713 tons of whey are generated annually. An important volume of this byproduct is produced in the Zulia State, becoming itself a source of peptides and proteins of high nutritional quality that has been subused. With the purpose of evaluating GMP isolation and yield from ricotta whey precipitation with 50% trichloroacetic acid treatment, 6 extractions where performed with this acid to 50 mL of each analyzed whey: ricotta whey, resuspended commercial whey and acid whey (negative control). By means of chemical tests and PAGE-SDS 15%, indirect presence of GMP was verified in all preparations. Bands of 6.5, 18.3 and 19.0 kDa were observed in ricotta and commercial whey. Bands of 18.3 and 19.0 possibly correspond to the peptide trimeric structure. GMP yield in terms of protein content was 1.17 mg/50mL (1.17%) and 4.51 mg/50mL (0.81%), for ricotta and commercial whey, respectively. Results show that it feasible to obtain preparations of GMP, however, in order to produce this peptide industrially for its use, evaluation of low cost procedures for GMP purification is required.

Palabras clave : Glycomacropeptide; PAGE-SDS; whey.