Purification and general properties of argininosuccinate lyase from jack bean, Canavalia ensiformis (L.) DC

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Abstract
1. Argininosuccinate lyase (EC 4.3.2.1) from jack bean [Canavalia ensiformis (L.) DC] seeds was purified 532-fold from an acetone–butanol-dried powder. 2. The enzyme functions reversibly and exhibits maximum stability at 16°. 3. At 16° it has a half-life (t½) of 263min. 4. The enzyme is both cold-labile (t½ 131min. at 0°) and heat-inactivated (t½ 74min. at 38°); inactivation appears to be irreversible. 5. Treatment of the acetone–butanol-extracted powder with sodium dodecyl sulphate increased the sensitivity of the enzyme to temperature (t½ 70min. at 0°; t½ 23min. at 38°). 6. Addition, to the purified enzyme, of a fraction containing lipid from the seed increased the half-life to about 510min. at either 0° or 38°. 7. Arginine or homoarginine, and to a smaller extent some other amino acids or fumarate, protected the enzyme from cold-inactivation. 8. Reactivation attempts with both the cold- and heat-inactivated enzyme failed. 9. The Km value for argininosuccinate at pH7·5 is 1·3×10−4. 10. The enzyme was inactivated completely within 15min. at 16° by 0·5mm-p-hydroxymercuribenzoate, and subsequent exposure to 5mm-cysteine had no restorative effect.