Snake venom L-amino acid oxidase

L-Amino acid oxidase undergoes two types of reversible inactivation one obtained by raising the pH from 5.5 to 7.5 and the temperature from 25 to 38 °C, while the second one is caused by storage at -5 to -60 °C and depends on the pH (it is favored by acidic pH values) and on the ionic composition of the storage buffer. In both cases reactivation is achieved by incubating the enzyme at pH 5 and 38 °C for Ih. Snake venom L-amino acid oxidases should be maintained in the dark at 4°C and near neutral pH to avoid inactivation. 

Dihydro-2/7-l,4-selenazine-3,5-dicarboxylic acid (162) is formed via the a-keto acid (161), which is obtained by the the deamination of selenolanthionine (160) with snake venom L-amino acid oxidase (Scheme 38) <90MI 624-01 >. The mono acid (164) is formed from the similar treatment of L-selenolysine (163), but its isomer (165) is the result of replacing the snake venom with diamine oxidase from pea seedlings (Scheme 39) <81MI 624-oi>. 

A much more active L-amino acid oxidase, discovered in snake venom by Zeller, has been isolated by Singer and Kearney and identified as a flavoprotein with FAD as the prosthetic group. The enzyme has a molecular weight of about 62,000, and the spectrum shows absorption bands at 389 and 465 m/x. With L-leucine as the substrate, the turnover number at 38° is 3100 moles of substrate oxidized per minute per mole of flavin even crude venom has higher activity than the purified rat liver enzyme. Snake venom L-amino acid oxidase exists in active and inactive forms which are interconvertible under the influence of pH and inorganic ions. 

---