Radiation target analysis indicates that phenylalanine hydroxylase in rat liver extracts is a functional monomer

FEBS Letters

Kaufman, Seymour²  Davis, Michael²  Kempner, Ellis S³  Parniak, Michael A¹ 

[1] Lady Davis Institute for Medical Research, SMBD-Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec H3T 1E2, Canada;National Institute of Mental Health, National Institutes of Health, Bldg. 6, Room 140, Bethesda, MD 20892, USA;National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA

关键词: Phenylalanine hydroxylase;    Radiation inactivation;    Functional size;    BH4;    tetrahydrobiopterin (6R-dihydroxypropyl-l-erythro-5;    6;    7;    8-tetrahydropterin);    6MPH4;    6-methyl-5;    6;    7;    8-tetrahydropterin;    PAH;    phenylalanine hydroxylase (phenylalanine 4-monooxygenase;    EC 1.14.16.1);   

DOI  :  10.1016/S0014-5793(99)00392-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The minimal enzymatically functional form of purified rat hepatic phenylalanine hydroxylase (PAH) is a dimer of identical subunits. Radiation target analysis of PAH revealed that the minimal enzymatically active form in crude extracts corresponds to the monomer. The ‘negative regulation' properties of the tetrahydrobiopterin cofactor in both crude and pure samples implicates a large multimeric structure, minimally a tetramer of PAH subunits. Preincubation of the samples with phenylalanine prior to irradiation abolished this inhibition component without affecting the minimal functional unit target sizes of the enzyme in both preparations. The characteristics of rat hepatic PAH determined by studies of the purified enzyme in vitro may not completely represent the properties of PAH in vivo.

【 授权许可】

Unknown