Nucleic Acid and Protein Concentration and Content: How to Measure & Why

American Meat Science Association Quantitative methods for determination of RNA, DNA, and protein concentrations in tissues, organs, cell cultures and biochemical assay systems have many applications. Protein concentration estimates are required to determine yield and extent of purification in enzyme isolations and assays, and in protein purification protocols. Protein concentrations must be known to standardize loading of electrophoresis gels, to standardize enzyme activities, to characterize ligand binding data in receptor assays, and to assess changes or differences in growth of individual skeletal muscles, other tissues, and organs. Protein concentration estimates are also required to estimate carcass composition and composition of gain responses to experimental treatments or manipulations, and in measurement of tissue-specific fractional protein synthesis rates. Protein concentration measurements are employed as part of FSIS standards of identity compliance in the manufacture of processed meat products (i.e. PFF, moisture-protein ratio and water-added specifications), as well as in least cost formulation of products from several sources of raw materials. Some applications require quick, less sensitive methods for process management, while others must conform to “official” methods requirements. Similarly, several applications of quantitative measures of RNA and DNA have evolved along with our improved understanding of the regulation of the cell cycle and rates of transcription and translation which lead to native or altered forms of important gene products. The emergence of molecular techniques used to study the regulation of gene expression, enumeration of specific microorganisms, and in investigations of mechanisms by which muscle and tissue growth are regulated require increased sensitivity, specificity, and use in liquid or solid phase formats. A single source of names, brief descriptions, and characteristics of these methods is lacking. Therefore, the objective of this reciprocation session was to share this information in concise form with AMSA members and meeting attendees, and to promote discussion on use of these methods. This summary of methods is produced with the objective of providing a practical list of commonly used techniques for total protein, RNA, and DNA concentration estimates in most mammalian tissues or combinations thereof. Methods described can be adopted with relative ease and confidence of good accuracy and precision being achieved if procedures are faithfully followed. Important considerations are mentioned to assist the reader in selection and application of the techniques. The summary does not provide protocol details for each method, nor is the list exhaustive; but it is intended to be used as a quick reference in a research or certified laboratory setting.