Constant urinary proteins in healthy humans in a 520-day isolation experiment

The aim of this study was the search of permanent proteins of the urinary proteome during a 520-day isolation experiment at the Institute of Biomedical Problems (IBMP) Ground-Based Test Facility in controlled conditions, using an autonomous life support system. The object of the study was urine sampled from 6 normal male subjects aged 25 to 37. The biological material samples (the second morning urine fractions) were collected for proteomic investigations against the background, on the 50th, 93rd, 124th, 153rd, 180th, 251st, 274th, 303rd, 330th, 371st, 400th, and 427th days of isolation, and on the 7th day after its completion. The samples were analyzed using chromatography–mass spectrometry, while the obtained results were analyzed using bioinformatics resources. The following seven permanent proteins were identified and observed during the entire period of urine investigations: epidermal growth factor, polymeric immunoglobulin receptor, plasma serine protease inhibitor, Alpha 1 microglobulin/bikunin precursor (AMBP), keratin (type II cytoskeletal 1), collagen alpha-1 (VI) chain, and serum albumin.