Use of IR absorption of the carboxyl group of amino acids and their metabolites to determine pKs, to study proteins, and to monitor enzymatic activity
✍ Scribed by Wayne W. Wright; Jane M. Vanderkooi
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 261 KB
- Volume
- 3
- Category
- Article
- ISSN
- 1075-4261
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✦ Synopsis
hexafluorovaline) and some of their metabolites ( a-ketoglutarate, oxalacetate, pyruvate, succinate, citrate, and acetate) were determined in the infrared (IR) region from 1300 to 1700 cm 01 under conditions that are appropriate for biological studies (i.e., in phosphate-buffered D 2 O solution). The strongest transition in this region is n a OCO , with an extinction coefficient Ç 1 mM 01 cm 01 , and an emphasis was made to demonstrate use of this transition for enzymatic assays and to study proteins. To these ends, these relevant features were demonstrated. The value for n a OCO is a function of the residue p K: the higher the frequency, the lower the p K of the carboxylic acid. The high extinction of n a OCO permits detection of carboxyl groups in parvalbumin, a protein that is rich in Asp and Glu. The IR profiles for the amino acids and their metabolite products are sufficiently characteristic so that IR can be used to monitor enzymatic reactions involving amino acids. We show that transaminase reactions, which interconvert amino and keto acids, can be monitored by IR.