Exploration of the six tryptophan residues of Escherichia coli cystathionine β-lyase as probes of enzyme conformational change.

•17 Site-directed variants of Escherichia coli cystathionine β-lyase.•6 Tryptophans of cystathionine β-lyase investigated as conformational probes.•Effect of substitutions on activity and stability generally negligible.•4 Native tryptophan residues can be substituted to simplify fluorescence spectrum.•Trp188 is a probe of conformational changes at the domain interface and active site.