Roles of N- and C-terminal domains in the ligand-binding properties of cytoglobin.

摘要: Cytoglobin (Cygb) is a member of the hexacoordinated globin protein family and expressed ubiquitously in rat human tissues. Although Cygb reportedly upregulated under hypoxic conditions both vivo vitro, suggesting physiological function to protect cells hypoxic/ischemic by scavenging reactive oxygen species or signal transduction, mechanisms associated with this have not been fully elucidated. Recent studies comparing Cygbs among several suggest that mammalian show distinctly longer C-terminal domain potentially involved unique functions. In study, we prepared mutants (ΔC, ΔN, ΔNC) either one terminal domains truncated investigated enzymatic functions structural features spectroscopic methods. Evaluation superoxide-scavenging activity between variants showed ΔC ΔNC exhibited slightly higher involving superoxide as compared wild-type Cygb. Subsequent experiments ligand titration, flash photolysis, resonance Raman suggested truncation C- N-terminal resulted less effective dissociation constants binding rates for carbon monoxide, respectively. Furthermore, stability was assessed guanidine hydrochloride revealed might play vital role improving structure, whereas did exert similar effect. These findings indicated long could be important only regulating but also stability, relevant other hypothesized