Precipitation of human serum albumin from yeast culture liquid at pH values below 5.

In vivo and in vitro experiments showed that human serum albumin (HSA) co-precipitated with components of the commonly used yeast peptone dextrose (YPD) growth medium in aqueous solutions at pH <5. Yeast extract was found to be the primary component of YPD responsible for HSA precipitation. Among yeast extract constituents, RNAs are likely to be most important for HSA precipitation.