Small heat shock proteins, e.g., Pyrococcus fuiosus (Pfu-sHSP), confer thermotolerance on cellular cultures and on proteins in cellular extracts during prolonged incubation at elevated temperature, demonstrating the ability to protect cellular proteins and maintain cellular viability under heat stress conditions. Such heat shock proteins are effective to combat enzymatic aggregation and intracellular precipitation during heat stress, and thereby enable enhancement of the utility and stability of enzymes in various applications, e.g., Taq polymerase in PCR applications, digestive enzymes in microbial degradative applications, etc.