A novel trypsin inhibitor from Peltophorum dubium seeds, with lectin-like properties, triggers rat lymphoma cell apoptosis

TRONCOSO, MARÍA FERNANDA; CERDÁ ZOLEZZI, PAULA; HELLMAN, ULF; WOLFENSTEIN-TODEL, CARLOTA.

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS

Elsevier Science

Lugar: Estados Unidos; Año: 2003 vol. 411 p. 93 - 104

0003-9861

A trypsin inhibitor (PDTI) was isolated from Peltophorum dubium seeds by affinity chromatography on a thyroglobulin-agarose or trypsin-agarose column. In both cases, SDS-PAGE showed two bands of Mr 20,000 and 22,000, which could not be resolved. Their amino-terminal sequence was identical and similar to Kunitz-type soybean trypsin inhibitor (SBTI). Mass spectrometry analysis of tryptic digests of both bands showed 16 coincident peaks, suggesting that they are closely related proteins. The Ki for trypsin and chymotrypsin inhibitory activity of PDTI was 1.6 x 10-7 M and 1.3 x 10-5 M, respectively. Lectin-like activity of PDTI and SBTI, detected by hemagglutination of rabbit erythrocytes, was inhibited by sialic acid containing compounds. PDTI and SBTI caused apoptosis of Nb2 rat lymphoma cells, demonstrated by decrease of viability, DNA hypodiploidy, DNA fragmentation and caspase-3-like activity. They had no effect on normal mouse splenocytes or lymphocytes, whereas they caused apoptosis of concanavalin A-stimulated mouse lymphocytes