Studies-of quantitative analysis of protein expression in Saccharomyces cerevisiae

In the present study amino acid analysis is applied to quantitation of Sacc haromyces cerevisiae proteome expression. The quantitation levels obtained are compared to data using densitometric analysis of silver or amido black staining and to the theoretical expression level (codon bias) of the identi fied proteins determined from their amino acid analysis (AAA). The results show that relative volume ratio (%vol) using Melanie II is a better paramet er for spot quantitation than relative optical density ratio (%OD), and ami no black staining provides good linearity within the range 1-100 pmol prote in. However, AAA shows that theoretical expression levels are not well corr elated with actual protein expression level, although there is better corre lation when isoforms of the expressed protein are identified and included. It is concluded that amino acid analysis provides accurate protein quantita tion and has a continuing role in proteome studies in terms of the rapid an d inexpensive quantitation of proteins displayed on proteome maps. We do ho wever recognize that in the context of future clinical applications and lar ge-scale proteome discovery projects, quantitation and post-translational m odification need to be analyzed by 'proteomatic' (ie., proteome automatic b ioinformatic analysis directly from the gel) techniques.