I noticed that lignin decolourization is generally measured using absorbance value at 280nm? However, protein/enzyme concentration is also measured at 280nm.
1. Is it possible that protein present in the media supernatant containing lignin also reflects in the absorbance value obtained for decolorization?
2. Can there be presence of a lot of protein/extracellular enzymes (or lignin degrading enzmes) in the supernatant that will overshadow the lignin decolourization, so there will be increased value of absorbance (at 280nm) instead of the expected decrease in absorbance value which shows decolourization?
Generally speaking, yes. It may or may not be a problem depending on the mutual ratio of lignins and proteins. In samples with low protein content, like wood or straw, this is not a problem. On the other hand, for example straw from biogasing reactor could be a difficult object for analisis becaus of all the bacterial proteins and enzymes. Then proteins or their dedraded residues could falsify the results.
In addition to the right answer from Jakub Szperlik concerning the low protein/lignin ratio, it seems to me that decoloration cannot be measured at 280 nm. This is UV and aromatic components absorb at that region.
Thanks everyone for your contributions, I also think protein might influence the absorbance value while studying lignin decolourization. Francisco Solano researchers often use 280nm because lignin has many aromatic rings in its structure and it is believed that degradation of lignin will lead to the break up of such aromatic structure, hence giving a reduction in absorption at 280nm.
Once again, thanks for taking your time to answer my question.
I see, thanks Esther Amosu, I thought that ligninolysis was through cleavage of the beta-O-4-bridge ether bonds, but the units after degradation still remain aromatic. If the aromatic ring is open and the aromatic ring are lost, your are right.
Dear esther,
I encountered the same problem when I was measuring the Acid Soluble LIgnin (ASL) lignin content of my biomass using a colorimetric assay. Later, I used a nanodrop and Bradford's assay of my acid pre-treated hydrolysate (neutralized later) to assess the protein content; there was very little protein as majority of it had got hydrolyzed during the acid treatment. Once the protein quantity (mg/mL) was recorded, I subtracted this value from the noted absorbance during lignin estimation, thereby eliminating doubts if I had protein interfering the Lignin estimation.
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Enzymology
- Enzymes