Thiol Redox Sensitivity of Two Key Enzymes of Heme Biosynthesis and Pentose Phosphate Pathways: Uroporphyrinogen Decarboxylase and Transketolase

Table 1

Label-free MS quantification of reversibly oxidised Cys residues of Hem12p and Tkl1p using Progenesis. Peptides detected in a shotgun proteomic screen of reversibly oxidised Cys residues using the redox affinity enrichment approach in WT and ΔGrx2 yeast strains ±1 mM H₂O₂. Units are arbitrary for intensity of parent ions.

Protein and Cys peptide	Peak intensity of oxidized Cys peptide (arbitrary units)
	WT	WT + H2O2	ΔGrx2	ΔGrx2 + H2O2
Tkl1p (Cys622)
LSVLPDNVPIMSVEVLATTCWGK	2.3	22.9**	9.5	58.5**
Hem12p (Cys26)
VERPPCWIMR	5.0	7.0	30.0*	23.2

*Hem12p had a sixfold increase in the detection of reversibly oxidised Cys26 in the ΔGrx2 strain compared to WT (𝑃=0.0042). **Tkl1p was increased in both strains after H₂O₂ treatment and more significantly in the ΔGrx2 strain; this peptide was detected with 𝑧=2 (𝑃=0.00471) and 𝑧=3 (𝑃=0.0109). Peak intensities are given in arbitrary units ×10⁴ (Tkl1p) and ×10³ (Hem12p).