Modulation of the thermal stability of β-lactoglobulin by transglutaminase treatment

The influence of microbial transglutaminase (MTGase) treatment in the presence and absence of dithiothreitol (DTT) on the thermal stability of beta-lactoglobulin (beta-LG) was investigated using size-exclusion chromatography (SEC) combined with on-line multiangle laser light scattering (MALLS) and UV detection. SEC-MALLS-UV analyses showed that moderate MTGase treatment (up to 6 or 9 h) led to the decline in thermal stability of beta-LG, while excess treatment (e.g. 23 h) resulted in remarkable increase, irrespective of whether the reducing agent DTT was present or not. The modulation in thermal stability may be attributed to the partial unfolding of protein molecules and the subsequent re-arrangement of conformation.