The study demonstrates the properties of conjugation of beta-galactosidase with a thermo-responsive polymer, poly-N-isopropylacrylamide (PNIPAAm) in comparison to a non-responsive polymer, polyacrylamide (PAAm). The maximum formation of bioconjugate (PNIPAAm-beta-galactosidase) was 75% (yield) with 50% chemically modified enzyme (using itaconic anhydride). The process of bioconjugation (bioconjugate concentration: 7.4%) decreases lower critical solution temperature from 32.5 degrees C (with pure PNIPAAm) to 26.5 degrees C. The effect of temperature on the activities of PNIPAAm-beta-galactosidase, PAAm-beta-galactosidase and native enzyme was also compared. At 70 degrees C, the maximum activity was observed for PNIPAAm-beta-galactosidase while for others it was at 60 degrees C. However, the effect of pH was insignificant on activities of both the bioconjugates than the native enzyme. The addition of ethylene glycol (20%, v/v) enhances the activity (by 45%) of PNIPAAm-beta-galactosidase with no loss in stability; however; the trend is reversed with the addition of ethanol. Further, employing bioconjugates even up to 24 cycles of precipitation (at 40 degrees C) followed by re-dissolution (4 degrees C) around 90% of activity could be retained by PNIPAAm-beta-galactosidase. The PNIPAAm-beta-galactosidase also showed much-improved thermal and storage stabilities. A lower Michaelis-Menten constant (K-m) was estimated with the PNIPAAm-beta-galactosidase than the native enzyme as well as PAAm-beta-galactosidase. Finally, PNIPAAm-beta-galactosidase was tested to synthesize galacto-oligosaccharides from lactose solution. (C) 2013 Elsevier Inc. All rights reserved.