With developments in recombinant DNA and fermentation technology, microbial sources, especially yeasts, can become significant sources of nutrients and specifically designed functional proteins and supplement conventional proteins. These developments underscore the need for practical methods for isolating functional proteins from yeast cells. In this review, the nature of the forces (hydrogen bonding, electrostatic interactions, hydrophobic and van der Waals interactions) responsible for stabilizing nucleoprotein complexes are described and methods for disrupting these as an approach for isolating proteins are discussed. The need for practical methods to recover functional proteins low in contaminant nucleic acids is emphasized.