Andean potato´s peptide inhibitors

MARIANA EDITH TELLECHEA; SEBASTIÁN MARTÍN TANCO; DANIELA LUFRANO; JAVIER GARCÍA PARDO; JULIA LORENZO; LAURA BAKAS; WALTER DAVID OBREGÓN.

Congreso; Latin American Crosstalk in Biophysics and Physiology, 2015; 2015

Peptide protease inhibitors (PPIs) are regulatory molecules, which function is critical for maintaining organism homeostasis. To date, several studies have been related the dysregulation of PPIs with a great diversity of human diseases [1]. Among PPIs, potato carboxypeptidase inhibitor (PCI) is one of the best studied proteinaceous inhibitors [2], having in vitro antimalarial [3] and anti-proliferative activities [4].This work presents the biochemical study of protease inhibitors from Andean potato?s extract.Carboxypeptidase A (CPA) inhibitory activity was determined, and the MALDI-TOF/MS analysis, displayed the presence of a molecule of 4310 Da., fairly close to the mass of PCI [2]. Then, we did the isolation and partial sequenciation of this molecule. Results showed that its N-terminal differs with PCI being more similar with a sequence previously determined from cDNA of S. tuberosum by Banfalvi on 1996. As key structural feature, this theoretical protein with 39 amino acids, has six cysteines, probably involved in the formation of three disulfide bonds which stabilize characteristic structure of these inhibitors. Besides, the molecular weight of this protein is 4310 Da coincident with the mass obtained on the extracts. No reports have been found on their inhibitory activity so we perform the expression and characterization of this newly described protein (SMCI).Furthermore, we analyze the structural homology of this theoretical protein and a new identification was obtained. The best match corresponds to a protein from S. lycopersicum. This protein, known as TCMP2, presents both CPA inhibitory and antiangiogenic activity.Here, we identified small proteins, with equal amino acid number and similar molecular weight, but with a low sequence homology. It would be interesting to know the common ancestor of these molecules and the reasons of sequence divergences. Furthermore, through the characterization of this new molecule, SMCI, we would like to contribute to determine its potential biomedical applications.[1] Georgie Fear, et al. Pharmacology & Therapeutics 113 354?368, 2007.[2] Ryan, C. A. Biochem. Biophys. Res. Commun. 44, 1265-1270, 1971.[3] Patent. International Publication Number PCT WO 2008/077977 Al.[4] Marta Sitjà-Arnau, et al Cancer Letters Volume 226, Issue 2, Pages 169?184, 2005.