[Essay of proteins after aldehyde treatment in biological objects (author's transl)]

Following fixation with formalin or glutaraldehyde, the protein content of bovine serum albumin, lysozyme, non-disintegrated yeast cells and liver nuclei of mice is determined by means of a brom-phenol blue staining procedure and the widely used Lowry-technique. The bromphenol blue technique permits determinations of soluble as well as particulate proteins or protein mixtures fixed with up to 6% formalin or 2% glutaraldehyde. Recovery rates differ no more than 20% as related to unfixed controls. Using the bromphenol blue method it is not necessary to separate aldehyde or any interfering material by additional steps prior to determination. Factors for correcting protein content of biological material after aldehyde treatment are available. In this way, comparative biochemical as well as cyto- and histochemical investigations of enzymatic activities after aldehyde fixation are possible. Some advantages of the bromphenol blue technique with special reference to the analysis of particulate and/or aldehyde-fixed specimens are discussed.