Determination of changes in protein conformation caused by pH and temperature

Protein denaturation has a major impact on meat quality parameters such as water holding capacity, tenderness and color. Specific information about structural changes of the individual muscle proteins post-mortem could help understand the factors affecting meat quality. An aromatic dye, 4,4′-dianilino-1,1′-binaphthyl-5,5′-disulfonic acid (bisANS) that binds to the hydrophobic patches of proteins was used to monitor changes in the conformation of individual sarcoplasmic proteins caused by pH. The bisANS reagent was covalently linked to the proteins with UV-light and the proteins were separated and identified using gel electrophoresis and mass spectrometry. The results showed that the sarcoplasmic proteins creatine kinase M, aldolase A and lactate dehydrogenase showed increased hydrophobicity whereas carbonic anhydrase III showed decreased hydrophobicity with increasing pH. Temperature only had a marked effect on the results at around 40 °C, there being no change between 25 and 35 °C.