Investigation of the post mortem zinc protoporphyrin IX fluorescence with respect to its protein-bound and unbound occurrence in aqueous meat extracts

• Published in: Food chemistry Vol. 283; pp. 462 - 467
• Main Authors: Ghadiri Khozroughi, Amin, Braga, Tess Waldbach, Wagner, Janine, Rawel, Harshadrai
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-06-2019
• Subjects: Animals; Chromatography, Gel; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Fluorescence screening; MALDI-TOF-MS; Meat; Meat - analysis; Meat Products - analysis; Myoglobin - chemistry; Myoglobin - metabolism; Post mortem chemistry; Protein Binding; Proteins - chemistry; Proteins - metabolism; Protoporphyrins - analysis; Protoporphyrins - chemistry; Protoporphyrins - metabolism; SDS-PAGE; SEC-HPLC; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Water - chemistry; PP; LL; RT; MALDI-TOF-MS; FECH; DMSO; PMF; Fluorescence screening; TFA; Meat; SDS-PAGE; Post mortem chemistry; Mb; FRC; HCCA; Hb; SEC-HPLC; DMF; ZnPP; CA; tR; FePP
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2019.01.080

•90% of zinc protoporphyrin IX is protein-bound at 0 h of extract-incubation.•The share of unbound zinc protoporphyrin IX rises from 10% to 50% within 72 h.•An unknown fluorescence peak was detected at a protein mass of >100 kDa.
Zinc protoporphyrin IX (ZnPP) is known to accumulate in most meat products during storage. However, the pathway of its formation is not yet completely clarified. To gain more insights into the specificity of ZnPP occurrence, a SEC-HPLC-UV-fluorescence setup was established to screen the proteins in aqueous meat extracts for their ZnPP fluorescence during incubation. In accordance with previous studies it was identified by SDS-PAGE and MALDI-TOF-MS that ZnPP formation takes place in myoglobin. In this study, valuable new insights into the ZnPP forming pathway were gained, as our results indicated that a significant part of ZnPP – after being formed within the protein – is transitioned into free ZnPP during incubation. Additionally, the obtained results implied that ZnPP may also occur in proteins of higher molecular weight (>100 kDa).