Complete Amino Acid Sequence of the Lentil Trypsin−Chymotrypsin Inhibitor LCI-1.7 and a Discussion of Atypical Binding Sites of Bowman−Birk Inhibitors

Abstract

The complete primary structure of the lentil (Lens culinaris) trypsin-chymotrypsin inhibitor LCI-1.7 was determined by conventional methods in order to find relationships between partial sequences and the difference in action against human and bovine chymotrypsin. As other Bowman-Birk type inhibitors, LCI-1.7 contained 68 amino acid residues, seven disulfide bridges, and two reactive sites, Arg16-Ser17 for trypsin and Tyr42-Ser43 for chymotrypsin. Evaluation of sequence homologies showed that it belonged to the group III Bowman-Birk inhibitors. The atypical additional binding site of LCI-1.7 for human chymotrypsin was discussed and compared with such binding sites of two other Bowman-Birk inhibitors, the Bowman-Birk soybean proteinase inhibitor BBI, and the lima bean proteinase inhibitor LBI I, for human and bovine trypsin and chymotrypsin. A concept to reduce the action of these inhibitors against human enzymes by genetic engineering was proposed.

Bowman-Birk inhibitors in lentil: Heterologous expression, functional characterisation and anti-proliferative properties in human colon cancer cells

“…This sequence turned out to be 342 nucleotides long from the ATG to the stop codon, corresponding to a putative protein of 113 amino acids. Comparison of the deduced sequence with that from BBI protein previously isolated from lentil seeds (Ragg et al, 2006;Weder & Hinkers, 2004) revealed that the transcript here described produced a longer putative protein. The in silico translation of the full-length cDNA showed additional 42 amino acid residues at the N-terminus, previously described as belonging to the precursor peptide (Sonnante et al, 2005), and five extra residues at the C-terminus which had not been previously described (Fig.…”

“…In this contribution, we have reported the isolation of a full-length cDNA coding sequence for lentil trypsin/chymotrypsin BBI; its in silico translated protein was longer than the sequence of the lentil BBI extracted and sequenced from seeds (Ragg et al, 2006;Weder & Hinkers, 2004). The pre-protein showed a long N-terminal peptide, like other legume protease inhibitors (Clemente, MacKenzie, Jeenes & Domoney, 2004;Domoney et al, 1995;Sonnante et al, 2005), and five extra residues (ELIKY) at the C-terminus.…”

“…In lentil, a legume originating in the Near East (Sonnante, Hammer, & Pignone, 2009), four BBI isoinhibitors have previously been isolated from seeds (Weder & Kahleyss, 1998), showing differential activity towards digestive enzymes (Weder & Kahleyss, 2003); the amino acid sequence was obtained from one of these isoforms and its trypsin and chymotrypsin inhibitory activity evaluated (Weder & Hinkers, 2004). The structure of a BBI trypsin/chymotrypsin inhibitor from lentil seeds was described by Ragg et al (2006).…”

“…The in silico translated protein was longer than the sequence of the lentil BBI extracted from seeds (Weder & Hinkers, 2004). Therefore, two different forms of the lentil inhibitor were considered: a C-terminally processed mature form, corresponding to the protein isolated from lentil seeds in vivo, hereafter named mature lentil BBI, and its C-terminally unprocessed form, called complete lentil BBI.…”

Inhibitory properties and solution structure of a potent Bowman–Birk protease inhibitor from lentil (Lens culinaris, L) seeds

“…The isolated 67 amino acid protein had the same primary structure as a recently published BBI, named LCI1.7, extracted from Lens culinaris var. Microsperma [22], with the exception of a C‐terminal missing glutamic acid residue (SwissProt Acc. No.…”