期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：5
页码：1414-1418
DOI：10.1073/pnas.70.5.1414
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Formation of 13C-resonances attributable to carbamino derivatives has been observed in human erythrocyte hemolysate preparations equilibrated with 13CO2 at 33{degrees}. Carbamino formation is most marked in deoxyhemoglobin and at alkaline pH, and is very largely inhibited by the addition of 2,3-diphosphoglycerate or conversion to oxyhemoglobin. The prominent carbamino resonance at 30.0 ppm upfield of CS2 is visible in the spectrum of packed, deoxygenated erythrocytes equilibrated in 13CO2. This chemical shift falls close to that observed with sperm-whale myoglobin and within 2 ppm upfield of that seen with simple amino acids and peptides. The bicarbonate-carbonate resonance near 33 ppm is broad in the hemoglobin preparations, which always contain some carbonic anhydrase, but becomes narrow in the presence of the carbonic anhydrase inhibitor, acetazolamide. The nuclear magnetic resonance condition of intermediate exchange rate with dissolved CO2 (68.4 ppm) obtains in the absence of inhibitor. The process has marked consequences in reducing the spin-lattice relaxation time, T1, of the bicarbonate resonance by more than 10 times. The deoxyhemoglobin carbamino resonance has a T1 value of 700 msec, indistinguishable from that of the protein carbonyl resonance envelope.
