Anomalous rotatory dispersion of aspartate-glutamate transaminase: The effects of carbonyl reagents and substrate analogues
✍ Scribed by Yu.M. Torchinsky; L.G. Koreneva
- Book ID
- 103964072
- Publisher
- Elsevier Science
- Year
- 1964
- Weight
- 233 KB
- Volume
- 79
- Category
- Article
- ISSN
- 0926-6577
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✦ Synopsis
Anomalous rotatory dispersion of aspartate-glutamate transaminase:
The effects of carbonyl reagents and substrate analogues
We have recently demonstrated z that the curve of optical rotatory dispersion of aspartate-glutamate transaminase (L-aspartate: a-oxoglutarate aminotransferase, EC 2.6. I. I) prepared from pig heart as the homogeneous pyridoxal-phosphate protein, exhibits a pronounced positive Cotton effect, the position of which depends on pH and coincides with absorption bands of the protein-bound pyridoxal phosphate (~m,x ----430 m~ at pH 4.8; 2m,x = 362 m/~ at pH 8.2). A somewhat smaller positive Cotton effect was observed in the absorption band with ~max ~ 335 m/z arising on reduction with NaBH 4 of the intramolecular aldimine bond between the C0-group of pyridoxal phosphate and the e-NH 2 group of a lysine residue in the enzyme protein, or on addition of a CN-group to this bond in the presence of KCN in excess 1.
Our further studies had the aim of ascertaining whether anomalous rotatory dispersion was displayed in the absorption band with ~,,., = 333 m/~, which appears in the spectrum of aspartate-glutamate transaminase on addition of aspartate or glutamate and is due to protein-bound pyridoxamine phosphate (refs. 2, 3). The pyridoxamine-phosphate form of aspartate-glutamate transaminase was prepared