Separation and Identification of Urinary Proteins Following Digital Rectal Examination in Patients with Benign Prostatic Hypertrophy

Specimens of urine were obtained before and after digital rectal examination from four patients with benign prostatic hypertrophy (BPH) for comparative analysis of protein components by reversed-phase high performance liquid chromatography. Four characteristic peaks were detected in urine after compared with before the physical examination, and their molecular masses on SDS-polyacrylamide gel electrophoresis were 16, 16, 34 and 46 kDa. After the proteins were reduced, S-pyridylethylated and cleaved with cyanogen bromide, the amino-terminal amino acids were sequenced and a homology search was conducted. The two 16-kDa proteins were both identified as fl-microseminoprotein. The 34-kDa protein was identified as a prostate-specific antigen, and the 46-kDa protein was a Zn-a2-glycoprotein. The present findings provide important information on pre-analytical sampling of urine for the diagnosis of BPH.