Enzymatic methods for the determination of l-serine concentration and l-[14C]serine specific radioactivity in blood plasma

✍ Scribed by A.I. Cassady; P.E.B. Reilly

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 618 KB
• Volume: 118
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(81)90151-2

✦ Synopsis

Methods are described for the use of L-serine dehydratase purified from Clostridium acidiurici for the determination of L-serine concentration and L[ 14C]serine specific radioactivity in sheep plasma. A spectrophotometric assay using this enzyme accurately measured the concentration of L-serine in standard solutions and in a commercially available mixture of amino acids and related compounds. This assay was shown to be suitable for measurement of plasma L-serine concentrations in excess of 30 pM. The reverse isotope dilution method was used for plasma L-[ 14C]serine specific radioactivity measurements. Carrier L-serine was added to plasma and separated from neutral and anionic compounds using ion-exchange chromatography. The L-serine was then converted to pyruvate with L-serine dehydratase and this was purified as the phenylhydrazone derivative. After recrystallization, drying and weighing, the derivative was assayed for radioactivity. The accuracy of this method was verified by adding L-[U-"Clserine to plasma and comparing the experimentally determined L-[ 14C]serine specific radioactivity with the calculated value. The method yielded a value which was 98.6 + 0.8% (5) of this calculated value.