Difference between human and guinea pig Hageman factors in activation by bacterial proteinases: cleavage site shift due to local amino acid substitutions may determine the activation efficiency of serime proteinase zymogens

Abstract

Human and guinea pig Hageman factors have been subjected to the action of pseudomonal elastase and serratial E15 proteinase. The pseudomonal elastase cleaved 22–24% of the human molecule at Arg 353-Val 354, and the remainder at Gly 357-Leu 358 resulting in the generation of about 20% of potential activity as activated Hageman factor, compared with trypsin activation, while ti hydrolyzed Arg 340-Ile 341 bond in guinea pig molecule and generated about 75% of activity as activated Hageman factor. The serratial proteinase did not hydrolyze the essential cleavage site (Arg 353-Val 354) of the human zymogen but Gly 356-Gly 357 (30%) and Gly 357-Leu 358 (70%) bonds. Both products showed no activity. The guinea pig zymogen, in contrast, was cleaved mostly at Arg 340-Ile 341 (70%) and less abundantly at Gly 344-Leu 345 (30%), generating about 85% of the whole potential activity as activated Hageman factor. From the high correspondence between the proportions of activationo of hydrolysis at the essential cleavage site in activation, it was concluded that hydrolysis of the bonds different from the essential bond did not cause activation, even when the spatial separation was only 3 or 4 residues. Considering the amino acid differences between human and guinea pig Hageman factors, - Met 351- Thr -Arg- Val -Val-Gly-Gly-Leu-Val-Ala 360- and - Leu 338- Ser -Arg- Ile -Val-Gly-Gly_leu-Val-Ala 347-, respectively, it was realized that even the minor amino acid substitutions caused the cleavage site shift which resulted in significant differences in activation efficiency of the proteinase zymogens.