Dataset Information

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

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 degrees . 3. At 16 degrees it has a half-life (t((1/2))) of 263min. 4. The enzyme is both cold-labile (t((1/2)) 131min. at 0 degrees ) and heat-inactivated (t((1/2)) 74min. at 38 degrees ); 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 (t((1/2)) 70min. at 0 degrees ; t((1/2)) 23min. at 38 degrees ). 6. Addition, to the purified enzyme, of a fraction containing lipid from the seed increased the half-life to about 510min. at either 0 degrees or 38 degrees . 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 K(m) value for argininosuccinate at pH7.5 is 1.3x10(-4). 10. The enzyme was inactivated completely within 15min. at 16 degrees by 0.5mm-p-hydroxymercuribenzoate, and subsequent exposure to 5mm-cysteine had no restorative effect.

SUBMITTER: Rosenthal GA

PROVIDER: S-EPMC1187728 | biostudies-other | 1969 May

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:The urea cycle consists of six consecutive enzymatic reactions that convert waste nitrogen into urea. Deficiencies of any of these enzymes of the cycle result in urea cycle disorders (UCD), a group of inborn errors of hepatic metabolism that often result in life threatening hyperammonemia. Argininosuccinate lyase (ASL) is a cytosolic enzyme which catalyzes the fourth reaction in the cycle and the first degradative step, that is, the breakdown of argininosuccinic acid to arginine and fumarate. Deficiency of ASL results in an accumulation of argininosuccinic acid in tissues, and excretion of argininosuccinic acid in urine leading to the condition argininosuccinic aciduria (ASA). ASA is an autosomal recessive disorder and is the second most common UCD. In addition to the accumulation of argininosuccinic acid, ASL deficiency results in decreased synthesis of arginine, a feature common to all UCDs except argininemia. Arginine is not only the precursor for the synthesis of urea and ornithine as part of the urea cycle but it is also the substrate for the synthesis of nitric oxide, polyamines, proline, glutamate, creatine, and agmatine. Hence, while ASL is the only enzyme in the body able to generate arginine, at least four enzymes use arginine as substrate: arginine decarboxylase, arginase, nitric oxide synthetase (NOS) and arginine/glycine aminotransferase. In the liver, the main function of ASL is ureagenesis, and hence, there is no net synthesis of arginine. In contrast, in most other tissues, its role is to generate arginine that is designated for the specific cell's needs. While patients with ASA share the acute clinical phenotype of hyperammonemia, encephalopathy, and respiratory alkalosis common to other UCD, they also present with unique chronic complications most probably caused by a combination of tissue specific deficiency of arginine and/or elevation of argininosuccinic acid. This review article summarizes the clinical characterization, biochemical, enzymatic, and molecular features of this disorder. Current treatment, prenatal diagnosis, diagnosis through the newborn screening as well as hypothesis driven future treatment modalities are discussed.

Project description:Serine proteases has been vastly reported to be found (and identified) only in seed extracts of Canavalia ensiformis (C. ensiformis), however, our group observed expressive serine protease activities in aqueous extracts from leaves, seeds, roots, and stem, especially in a leaf extract obtained with distillated water (CE-A). Additionally, this extract demonstrated very good stability in high temperatures and in the presence of chemical agents. In order to study the serine protease activity in leaves, CE-A was submitted to benzamidine-sepharose affinity column and an enriched fraction of serine proteases, named CE-ABza was purified 1.65 fold, yielding a total recovery of about 62%. Based upon zymographic analysis in a gelatin-SDS-PAGE-, the CE-ABza fraction presented an enzymatic activity band at approximately 90 kDa molecular mass region under non-reducing conditions and three bands at 17, 32 and also at 90 kDa under reducing condition. This fraction was able to hydrolyze, in a different way, peptidomimetic and protein substrates. The maximal activity was observed at basic pH values (8.0 to 9.5) and temperature about 40°C. These enzymes exhibited important thermal stability and were significantly inhibited by serine protease inhibitors, such as benzamidine and TPCK. Calcium, magnesium, manganese and zinc ions had a negative modulation on the CE-ABza activity. Mass spectrometry-based proteomics approach identified showed homology with 11 plant proteases from different legumes species, indicating their presence or demonstrating that CE-Bza proteases share specific region of the primary structure of theses enzyme, although the C. ensiformis genome and protein databases are yet to be publicly available. These results demonstrated that these molecules found in both the CE-A extract and the CE-ABza fraction presented important properties that could be used as potential pharmacological and biotechnological targets as therapeutic option. Besides, identification and characterization of C. ensiformis proteases contribute to the studies of plant enzymes.

Dataset Information

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

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure