Files in this Data Supplement:

• Supplemental file 1 - Supplemental text and legends to Fig. S1 to S5.
  MS Word file, 44K.
• Supplemental file 2 - Fig. S1 (Mdm2 levels are stable in the presence of heme).
  Zipped TIF file, 208K.
• Supplemental file 3 - Fig. S2 (Heme binds to PAS-A subdomain of hPer2 with equimolar stoichiometry A).
  Zipped TIF file, 208K.
• Supplemental file 4 - Fig. S3 (hCry1 levels are stable in the presence of heme).
  Zipped TIF file, 660K.
• Supplemental file 5 - Fig. S4 (Tryptophan fluorescence studies of heme-hPer2 interaction).
  Zipped TIF file, 65K.
• Supplemental file 6 - Fig. S5 (hPer2 stability in response to oxidative stress conditions).
  Zipped TIF file, 506K.