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

In this study, we prepared human Cygb mutants (ΔC, ΔN, and ΔNC) with either one or both terminal domains truncated and investigated the enzymatic functions and structural features by spectroscopic methods. Evaluation of the superoxide-scavenging activity between Cygb variants showed that the ΔC and ΔNC mutants exhibited slightly higher activity involving superoxide scavenging as compared with wild-type Cygb. Subsequent experiments involving ligand titration, flash photolysis, and resonance Raman spectroscopic studies suggested that the truncation of the C- and N-terminal domains resulted in less effective to dissociation constants and binding rates for carbon monoxide, respectively. Furthermore, structural stability was assessed by guanidine hydrochloride and revealed that the C-terminal domain might play a vital role in improving structure, whereas the N-terminal domain did not exert a similar effect. These findings indicated that long terminal domains could be important not only in regulating enzymatic activity but also for structural stability, and that the domains might be relevant to other hypothesized physiological functions for Cygb. PMID: 29149638 [PubMed - as supplied by publisher]
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research