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Stimulation and partial stabilization of human histidyl-tRNA synthetase by hemoglobin
T Biswas1, F W Miller, P H Plotz
1Arthritis and Rheumatism Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, MD 20892.
Abstract:
Histidyl-tRNA synthetase, an enzyme against which antibodies are directed in some patients with polymyositis, has been purified 5000-fold from HeLa cells, but was extremely labile to dilution or on storage at -80 degrees C. In order to facilitate study of the biochemical and immunological properties of the enzyme, a stabilizer was sought. Hemoglobin at 2 mg/ml was found to stimulate the enzyme and also partially preserved the activity of the enzyme stored at a low concentration (less than 10 micrograms/ml). Hematin, but not the globin protein, could substitute for hemoglobin in stimulating the enzyme.