passages.id: split_1_test_1773_passage
passages.type: progene_text
passages.text: Here , we demonstrate that cysteine sulfinic acid is also a partial substrate for E. coli asparagine synthetase , acting as a nucleophile to form the sulfur analogue of beta-aspartyl-AMP , which is subsequently hydrolyzed back to cysteine sulfinic acid and AMP in a futile cycle .