In this work we establish the relationship between chemical glycosylation and protein thermodynamic, kinetic, and colloidal stability. While there have been reports in the literature that chemical glycosylation modulates protein stability, mechanistic details still remain uncertain. To address this issue, we designed and coupled monofunctional activated glycans (lactose and dextran) to the model protein alpha-chymotrypsin (alpha-CT). This resulted in a series of glycoconjugates with variations in the glycan size and degree of glycosylation. Thermodynamic unfolding, thermal inactivation, and temperature-induced aggregation experiments revealed that chemical glycosylation increased protein thermodynamic (Delta G(25 degrees C)), kinetic (t(1/2)(45 degrees C)), and colloidal stability. These results highlight the potential of chemical glycosylation with monofunctional activated glycans as a technology for increasing the long-term stability of liquid protein formulations for industrial and biotherapeutic applications. (c) 2006 Wiley Periodicals, Inc.