The metabolism of l-asparagine in asparagus officinalis

Abstract

1. 1. l-Asparagine is present at a concentration ranging from 0.004–0.04 M in Asparagus officinalis. 2. 2. Sensitive radiometric techniques have been used to examine enzymes responsible for the synthesis and metabolism of l-asparagine in Asparagus. 3. 3. l-Asparagine synthetase was undetectable but p-cyano-L-alanine synthase was abundant. 4. 4. Additionally, β-cyano- l-alanine hydratase, several l-asparagine transaminases and a feeble, possibly exogenous, l-asparaginase were also detectable. 5. 5. Attempts to measure the substrates of β-cyano- l-alanine synthase in freeze-clamped specimens indicated that both l-eysteine and cyanide were present at concentrations well below the K m of the enzyme for them. 6. 6. Studies to demonstrate alternate routes for the biosynthesis of l-asparagine failed; thus, β-cyano- l-alanine synthase remains the most plausible candidate as the primary participant in the biosynthesis of l-asparagine in Asparagus.