Methods and compositions for performing nucleic acid duplication and amplification reactions are provided. A single-stranded nucleic acid binding protein is selected and provided in the reaction mixture which is assembled at a low, nonstringent temperature to include all of the necessary reagents for successful nucleic acid duplication or amplification reactions. By incorporating a single-stranded nucleic acid binding protein into the reaction mixture at low temperature, the generation of nonspecific products such as amplification products is improved despite the reaction mixture having been fully assembled at a nonstringent temperature.