Purification and Characterization of Aspartate Aminotransferase Isoenzymes from Rice Bran

Yagi, Toshiharu; Sako, Masayuki; Moriuti, Shinya; Shounaka, Masafumi; Masaki, Kazunari; Yamamoto, Satoshi

doi:10.1271/bbb.57.2074

Cited by 11 publications

(7 citation statements)

References 9 publications

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“…The molecular weight and pI values (Table 1) are very similar to those that were found by other authors and in other plant species (Reynolds et al, 1981;Griffith and Vance, 1989;Turano et al, 1990;Yagi et al, 1993). SDS-PAGE shows a single band for each isoenzyme, indicating a similar sub-unit molecular weight.…”

Section: Resultssupporting

confidence: 87%

“…Both isoenzymes showed a high affinity for keto-acid substrates, and a higher affinity to aspartate than glutamate. These results agree with other AAT isoenzymes that were studied from different sources (Reynolds et al, 1981;Griffith and Vance, 1989;Turano et al, 1990;Yagi et al, 1993). The reaction mechanism for both AAT-1 and AAT-2 was determined from the double reciprocal plots of the initial velocity against the concentration of one substrate at a fixed concentration of the other substrate.…”

Section: Gel Exclusion (Da)supporting

confidence: 85%

“…In the reverse reaction in which L-glutamate and oxaloacetate are substrates, optimum pH for AAT-1 and AAT-2 was 7.5-8.5 and 8.5-9.0, respectively. Other studies showed only small differences in pH optimum values, according to different sources of the AAT isoenzymes (Reynolds et al, 1981;Griffith and Vance, 1989;Turano et al, 1990;Yagi et al, 1993). For AAT isoenzymes from rice bran, Yagi et al (1993) found some differences on optimum pH curves between the forward and reverse reactions.…”

Section: Gel Exclusion (Da)mentioning

confidence: 90%

“…Other studies showed only small differences in pH optimum values, according to different sources of the AAT isoenzymes (Reynolds et al, 1981;Griffith and Vance, 1989;Turano et al, 1990;Yagi et al, 1993). For AAT isoenzymes from rice bran, Yagi et al (1993) found some differences on optimum pH curves between the forward and reverse reactions. The forward reaction appears to be less pH dependent than the reverse reaction, although both isoenzymes showed a similar behavior with rapidly decreasing enzymatic activity above pH 8.…”

Section: Gel Exclusion (Da)mentioning

confidence: 90%

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Characterization of Aspartate Aminotransferase Isoenzymes from Leaves of Lupinus albus L. cv Estoril

Ml¹,

Mp²,

Ap³

2002

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Two aspartate aminotransferase (EC 2.6.1.1) isoenzymes (AAT-1 and AAT-2) from Lupinus albus L. cv Estoril were separated, purified, and characterized. The molecular weight, pI value, optimum pH, optimum temperature, and thermodynamic parameters for thermal inactivation of both isoenzymes were obtained. Studies of the kinetic mechanism, and the kinetics of product inhibition and high substrate concentration inhibition, were performed. The effect of some divalent ions and irreversible inhibitors on both AAT isoenzymes was also studied. Native PAGE showed a higher molecular weight for AAT-2 compared with AAT-1. AAT-1 appears to be more anionic than AAT-2, which was suggested by the anion exchange chromatography. SDS-PAGE showed a similar sub-unit molecular weight for both isoenzymes. The optimum pH (between 8.0 and 9.0) and temperature (60-65ºC) were similar for both isoenzymes. In the temperature range of 45-65ºC, AAT-2 has higher thermostability than AAT-1. Both isoenzymes showed a high affinity for keto-acid substrates, as well as a higher affinity to aspartate than glutamate. Manganese ions induced an increase in both AAT isoenzymes activities, but no cooperative effect was detected. Among the inhibitors tested, hydroxylamine affected both isoenzymes activity by an irreversible inhibition mechanism.

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Section: Resultssupporting

confidence: 87%

Section: Gel Exclusion (Da)supporting

confidence: 85%

Section: Gel Exclusion (Da)mentioning

confidence: 90%

Section: Gel Exclusion (Da)mentioning

confidence: 90%

See 2 more Smart Citations

Characterization of Aspartate Aminotransferase Isoenzymes from Leaves of Lupinus albus L. cv Estoril

Ml¹,

Mp²,

Ap³

2002

BMB Reports

View full text Add to dashboard Cite

show abstract

“…They couple the protein, carbohydrate, and fat metabolism and tricarboxylic acid cycle. AlAT was extensively studied in plants, animals, and microorganisms: primary structure (Good and Muench, 1992;Tanaka et al , 1992;Umemura et al , 1994;Wadsworth et al , 1995;Petrovic et al , 1996), amino acid composition (Ovchinnikov et al , 1972;Kagamiyama et al , 1977;Ishiguro et al , 1991;Wadsworth et al , 1995), isoelectric points (pI) (Yamamoto et al , 1992;Yagi et al , 1993;Umemura et al , 1993;Petrovic et al , 1996); crystals were obtained and X-ray crystallographic analysis was carried out (Kochkina, 1991(Kochkina, , 2000. However, the data about transaminases of fishes are still scarce.…”

mentioning

confidence: 99%