Thiourea enhances mapping of the proteome from murine white adipose tissue

Adipose tissue imposes problems in two-dimensional (2-D) analysis due to it s extremely high content of fat. To improve protein separation detergents a nd chaotropes were varied in the IEF step. The most important factor for ob taining distinct spots in the 2-D gel was whether thiourea was included or not. Many high molecular weight spots became resolved by using thiourea, wh ile no spots disappeared or showed inferior characteristics, thus approxima tely twice as many spots were possible to quantify. Hydrophobic indices wer e compared for a set of proteins that gave rise to sharper spots with prote ins that were not improved on the use of thiourea. The comparison did not g ive any statistically significant difference between the two groups of prot eins. One of the effects obtained by inclusion of thiourea was that the dom inating protein, serum albumin, appeared as more condensed spots allowing o ther minor proteins to be detected. This work resulted in a protocol which greatly enhances the resolution of proteins in adipose tissue. A 2-D map of mouse white adipose tissue from epididymal fat pads was constructed in whi ch 140 spots were identified by mass spectrometry. This work lays the groun d for our further studies on white adipose tissue in metabolic diseases suc h as obesity and dyslipidemia.