Calorimetric Analysis of the Plasma Proteome

Abstract

The plasma proteome is a complex mixture of over 3000 proteins that has been routinely exploited by physicians for clinical diagnostic assays. More recently, the low abundance region of the proteome has been examined for potential biomarkers of disease. A novel calorimetric assay has been developed that exploits a new physical basis with which to interrogate the plasma proteome. This section provides a brief overview of the use of the plasma proteome in clinical diagnosis and biomarker discovery and then introduces the new calorimetric assay. Some initial results are reported that indicate the potential clinical utility of the assay.

Differential Scanning Calorimetry, as a New Method to Monitor Human Plasma in Melanoma Patients with Regional Lymph Node or Distal Metastases

“…Garbett and co-workers demonstrated in these calorimetric studies average thermograms for individuals diagnosed with various diseases (Lyme disease, rheumatoid arthritis) and cancers (endometrial, ovarian, lung), among others in 5 patients with MM. These data suggest that each type of cancer or disease may have a characteristic signature in their thermogram (Garbett, et al, 2007(Garbett, et al, , 2009Michnik, 2011). This method is based on the biophysical technique of DSC, which monitors heat changes in a sample as a function of temperature.…”

Preliminary use of differential scanning calorimetry of cerebrospinal fluid for the diagnosis of glioblastoma multiforme

“…In this communication, we describe the use of differential scanning calorimetry (DSC), which exploits the high sensitivity of modern microcalorimeters, to reliably measure heat changes of 0.1 microcalories and thus indirectly measure complex molecule (i.e., protein-protein) interactions [6,7]. This technique has recently been used to study disease-specific changes in blood plasma proteome [8][9][10], and its efficiency has been demonstrated for identification of cervical cancer and several autoimmune diseases [11,12]. We hypothesized that DSC can be used to probe characteristic changes in denaturation profiles (thermograms) of the CSF proteome associated with GBM biomarkers.…”

Profile of systemic treatment with the antiviral lectin Griffithsin in guinea pigs.

“…The changes in the disease thermogram are proposed to be a manifestation of the interactome hypothesis where low molecular weight proteins or peptides unique to a disease state bind to the more abundant plasma proteins and alter normal interactions between them [101]. DSC is extremely sensitive to changes in concentration of protein components in a mixture as well as to binding interactions between components making this a powerful technique to probe perturbations in the plasma interactome [102]. Measuring a small protein's impact on the more abundant plasma proteins can provide invaluable data to describe stabilizing and destabilizing effects that a protein may have when introduced into a system.…”

“…Differences in heat flow as a consequence of thermal events occurring in the sample cell provide a characteristic curve, or thermogram, in the form of excess heat capacity of the sample as a function of temperature [102]. Every protein has a characteristic denaturation thermogram reflecting a unique thermodynamic signature for the melting of the tertiary structure of that protein [100].…”

“…For a mixture of proteins, such as plasma, the thermogram reflects the superposition of the denaturation thermograms of the major protein components according to their relative concentration and the presence of any binding interactions [100]. Observation of changes in the plasma thermogram as a consequence of binding allows the quantification of binding interactions through comparative shifts in denaturation temperatures of the major plasma proteins [102]. For example, a protein ligand which prefers the denatured state of a larger protein will result in a decrease in the denaturation temperature of the larger protein once bound [96].…”