Biochemical and Biophysical Research Communications, Vol.340, No.3, 823-828, 2006
Introduction of alpha-hydroxymethyamino acid residues in substrate specificity P1 position of trypsin inhibitor SFTI-1 from sunflower seeds retains its activity
In many complexes formed by serine proteinases and their inhibitors, the hydroxyl group provided by water molecule or by the inhibitor Ser residue is located close to the inhibitor P-1-P-1' reactive site. In order to investigate the role of this group, we synthesized analogues of trypsin inhibitor SFTI-1 isolated from the seeds of sunflower modified in P-1 by alpha-hydroxymethylserine (HmSer) and both enantiomers of alpha-hydroxymethylvaline (HmVal). All the synthesized analogues inhibited bovine beta-trypsin and human leukocyte elastase. SFTI-1 analogues with HmVal and HmSer appear to be potent inhibitors of bovine beta-trypsin, whereas [Val(5)]SFTI-1 is practically inactive. Also trypsin inhibitory activity of [Ser(5)]SFTI-1 is significantly lower. Since the electrostatic interaction between protonated epsilon-NH2 group of the inhibitor P-1 position and beta-carboxylate of trypsin Asp(189) is the main driving force for interaction of both molecules, the results obtained are very interesting. We believe that these SFTI-1 analogues belong to a novel class of serine proteinase inhibitors. (c) 2005 Elsevier Inc. All rights reserved.