Structural studies of a small (linear, cyclic) peptide as a synthetic substrate for thermolysin

A synthetic peptide substrate, allowing a cleavage bond (GF) for the specif ic thermolysin and a switchable S-S bridge (reduced - linear- and oxidised - cyclic- form) was designed, synthesised, and enzymatically studied. Despi te the fact that strong substrate structural constraints are supposed to ap pear with the S-S bridge presence, the catalytic behaviour of the thermolys in does not seem strongly affected on the cyclic form compared to the linea r one. The two different forms of the peptide structure was studied using t heoretical secondary structure prediction, optical spectroscopic methods (C D, FTIR, Raman) and molecular modelling studies. Our results are discussed and correlated in term of structure-function and/or structure activity rela tionships. (C) 1999 Elsevier Science B.V. All rights reserved.