Cancer proteomics: the state of the art.

Now that the human genome has been determined, the field of proteomics is ramping up to tackle the vast protein networks that both control and are controlled by the information encoded by the genome. The study of proteomics should yield an unparalleled understanding of cancer as well as an invaluable new target for therapeutic intervention and markers for early detection. This rapidly expanding field attempts to track the protein interactions responsible for all cellular processes. By careful analysis of these systems, a detailed understanding of the molecular causes and consequences of cancer should emerge. A brief overview of some of the cutting edge technologies employed by this rapidly expanding field is given, along with specific examples of how these technologies are employed. Soon cellular protein networks will be understood at a level that will permit a totally new paradigm of diagnosis and will allow therapy tailored to individual patients and situations.

Comparison of Ellman's reagent with N-(1-pyrenyl)maleimide for the determination of free sulfhydryl groups in reduced cellobiohydrolase I from Trichoderma reesei.

The enzyme cellobiohydrolase I (CBH I) from Trichoderma reesei was treated with 5 mM dithiothreitol at different pH values in order to reduce some or all of its 12 disulfide bridges. A discrepancy was found in the number of free sulfhydryl (SH) groups generated upon the reduction of CBH I when they were measured using N-(1-pyrenyl)maleimide (PM) or Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoic acid). For example, the number of SH mol generated/mol CBH I at pH 8.5 was determined to be 16 and < 1 when measured using PM or Ellman's reagent, respectively. The low value obtained with Ellman's reagent may be due to the electrostatic repulsion between the carboxylic acid groups in CBH I and those in Ellman's reagent. The fluorimetric assay used for determining SH molecules in reduced CBH I, based on their reaction with PM, is described.