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Site‐directed mutants of human myeloperoxidase A topological approach to the heme‐binding site
Author(s) -
Jacquet Alain,
Deleersnyder Virginie,
Garcia-Quintana Lida,
Bollen Alex,
Moguilevsky Nicole
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80437-l
Subject(s) - heme , mutant , myeloperoxidase , binding site , chemistry , biochemistry , microbiology and biotechnology , biology , enzyme , gene , immunology , inflammation
Two site‐directed mutants of human promyeloperoxidase, MPO(His 416 →Ala) and MPO(His 502 →Ala), have been expressed in Chinese hamster ovary cells and purified. Overall purification yields and apparent molecular masses of the mutant proteins were similar to those of the wild‐type enzyme. Both mutant species were analyzed spectroscopically to check the presence of the hemic iron in the proteins and were assayed for peroxidasic activity. The data show that substitution of His 502 leads to the loss, or to an inappropriate configuration, of the heme together with the loss of activity, suggesting that this residue could be the proximal His involved in the binding to the iron centers. On the other hand, substitution of His 416 by alanine had no effect on either of the studied parameters.