水稻的苯丙胺酸及酪胺酸去胺酶：I.酶的一般性質

L-Phenylalanine and L-Tyrosins Ammonia-lyase in Rice: 1. Some Properties of the Enzymes

童武夫(W. F. Tong) ； 魯平美(P. M. Luu) ； 黃雪嬌(S. J. Huang)

《師大生物學報》 15卷 (1980/12) Pp. 67-74

https://doi.org/10.29812/BBNTNU.198012.0008

摘要

水稻白化幼苗的上胚軸抽取液，可以測得苯丙胺酸及酪胺酸兩種去胺酶活性。於40～60%硫酸銨分割部份含有約百分之六十的酶總活性。苯丙胺酸去胺酶在5至60mM苯丙胺酸濃度範圍內，測得之Km值為6.45×10^-3。其最適當酸鹼值也如同其他植物組織的苯丙胺酸去胺酶一樣，為pH 9.0。酪胺酸去胺酶之Km值則為0.67×10^-3M。其最適當酸鹼值為pH 6.0，但在pH 9.0下其活性仍有百分之七十。在試管中以氧化或還原劑處理酶抽取液，並不影響苯丙胺酸去胺酶的電泳性質，但卻促進酶分子聚集現象的加強。特別是以2mM oxidized glutathione處理後，會使大部份酶活性消失。

並列摘要

Ammonia-lyase activities for both L-phepylalanine and L-tyrosine can be detected in the extract of epicotyls of etiolated rice seedlings. About 60 % of the activities of both enzymes could be recovered in the fraction of 40 to 60 % ammonium sulfate precipitation.Km value of phenylalanine ammonia-lyase which was determinated in the range of substrate concentration from 5 to 60 mM, was 6.45 x 10^-3M. The pH optimum of enzyme was 9.0 as the same as that in other plant tissues. Whereas, the Km, value of tyrosine ammonia-lyase was 0.67 x 10^-3 M. Its pH optimum was observed at 6.0 and about 70% activity was measured at pH 9.0. After in Vitro treatment of enzyme extract by oxidative or reductive reagents the electrophoretic pattern of phenylalanine ammonia-lyase was unaffected, but the aggregation of enzyme molecules exhibited more conspicuous. Most of the enzyme activity was losed by incubation of 2 mM oxidized glutathione.