Premium
Affinity Labeling of an Electron Transfer Pathway in Azurin by Cr(II) Ions
Author(s) -
Farver Ole,
Pecht Israel
Publication year - 1981
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198100004
Subject(s) - azurin , chemistry , chromium , peptide , electron transfer , trypsin , amino acid , yield (engineering) , ion , chymotrypsin , crystallography , biochemistry , enzyme , organic chemistry , materials science , metallurgy
Pseudomonas aeruginosa azurin is stoichiometrically reduced by chromium (II) ions to yield a relatively inert chromium (III) complex with azurin. When this derivative is proteolytically digested by either trypsin or chymotrypsin, only a single, yet different peptide labeled with chromium is obtained upon chromatographic separations. Amino acid analysis of these fragments shows that the tryptic peptide consists of residues Val‐80 to Lys‐92, while the chymotryptic peptide consists of the Thr‐84 to Val‐95 fragment. Based on the above findings, the chemical nature of the amino acid side chains of these peptides and the crystallographic model of azurin, it is suggested that the chromium is coordinated to Lys‐85 and Glu‐91. This assignment and the analysis of the three dimensional model of azurin serve in delineating an electron transfer pathway. A resonance transfer from an opening in the peptide sheath to Cu(II) through an extended relay of the aligned imidazoles of His‐35 and His‐46 is proposed.