Abstract

Chemical modification of human degraded form of plasminogen with NH2-terminal lysine (Lys-plasminogen) and the elastase fragments kringle 1 + 2 + 3 and kringle 4 with the tryptophan reagent [14C]dimethyl(2-hydroxy-5-nitrobenzyl)sulfonium bromide results in the incorporation of label and the parallel loss of lysine binding ability. In the case of kringle 4, only one-half of the lysine binding sites could be inactivated, but the modified and unmodified forms could be separated by affinity chromatography. The modified form contained 1 mol of 2-hydroxy-5-nitrobenzyl groups/mol of kringle 4 and did not bind to lysine-Sepharose. Lysine analogs such as 6-aminohexanoic acid protected kringle 4 against modification. Peptide-mapping studies on this form showed that essentially all of the label was in two chymotryptic peptides containing a tryptophan corresponding to Trp426 in the plasminogen sequence. Competition experiments with anti-kringle 4 antibodies having an affinity for the lysine binding site showed that the binding of 2-hydroxy-5-nitrobenzyl-kringle 4 to antibodies was about 10 times weaker than for unmodified kringle 4. These results indicate that the integrity of specific tryptophan residue is critical to the binding of lysine and related amino acids to kringle 4of human plasminogen.

Highlights

  • + plasminogen with NH2-terminallysine (Lys-plasminogen) and the elastase fragments kringle 1 + 2 3 and five weaker ones

  • Kringle 1, obtained by chymotryptic digestion of kringle 1 2 + 3, contains one strong andpossibly one weak binding site [19]. the complete amino acid sequence of plasminogen has been determined, littleis known about thechemical nature of the lysine binding sites

  • We show that chemical modification of a single tryptophan residue in kringle 4 abolishes lysine binding activity and provides evidence that thisresidue is at against modification

Read more

Summary

Introduction

+ plasminogen with NH2-terminallysine (Lys-plasminogen) and the elastase fragments kringle 1 + 2 3 and five weaker ones. The modifiedform contained 1mol of2-hydroxy-5-nitrobenylgroups/mol ofkringle 4 and didnot bind to lysine-Sepharose Lysine analogs such as 6-aminohexanoic acid protected kringle 4. Competition experiments with anti-kringle 4 antibodies having an affinity for the lysine binding site showed that the binding of 2-hydroxy-5-nitrobenzyl-kringl4e to antibodies was about 10 times weaker than for unmodified kringle 4. These results indicate that the integrity of specific tryptophan residue is critical to the Preparation of Plasminogen a n d of Kringle Fragments-Lysplasminogen‘ was prepared from Cohn fraction IIS (a gift of the American Red Cross) without separationof affinity forms as described earlier [16]. Chemical Modificatzon-[’4C]-2-Hy~oxy-5-nitrobenzyb~romide binding of lysine and related amino acids to kringle 4 was prepared using

Objectives
Results
Conclusion
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call