l-Serine, d- and l-proline and alanine as respiratory substrates of Helicobacter pylori: correlation between in vitro and in vivo amino acid levels

Abstract

Helicobacter pyloriwhole cells showed high rates of oxygen uptake withl-serine andl-proline as respiratory substrates, and somewhat lower rates withd-alanine andd-proline. These respiratory activities were inhibited by rotenone and antimycin A at low concentrations. Since pyruvate was produced froml-serine andd- andl-alanine in whole cells, the respiratory activities with these amino acids as substrates occurred via pyruvate. Whole cells showed 2,6-dichlorophenolindophenol (DCIP)-reducing activities withd- andl-proline andd-alanine as substrates, suggesting that hydrogen removed from these amino acids also participated in oxygen uptake by the whole cells. High amounts ofl-proline,d- andl-alanine, andl-serine were present inH. pyloricells, and these amino acids also predominated in samples of human gastric juice.H. pyloriseems to utilized- andl-proline,d-alanine andl-serine as important energy sources in its habitat of the mucous layer of the stomach.