Santoro J, Juretschke H P, Rüterjans H
Biochim Biophys Acta. 1979 Jun 19;578(2):346-56. doi: 10.1016/0005-2795(79)90165-x.
The proposed interaction between the amino acid residues Asp 14 and His 48 of ribonuclease A has been confirmed by 13C-NMR spectroscopy. The titration behaviour of the resonance of the side-chain carboxyl group of Asp 14 suggests a pKa of 6.5--7.0 for His 48. An equilibrium between different conformation process of His 48. Upon this deprotonation a hydrogen bond between the side-chains of Asp 14 or His 48 and Tyr 25 seems to be formed as is suggested by the behaviour of a tyrosine C zeta resonance assigned to Tyr 25. One phenylalanine resonance broadens and moves upfield on the addition of the inhibitor Cyd-2'-P, being therefore assigned to Phe 120. The behaviour of this resonance suggests that the upfield shift results from the anisotropy of the cytidine ring. Three signals are assigned to the three Phe residues.
核糖核酸酶A的天冬氨酸残基14与组氨酸残基48之间可能存在的相互作用已通过13C核磁共振光谱得到证实。天冬氨酸残基14侧链羧基共振的滴定行为表明组氨酸残基48的pKa为6.5 - 7.0。组氨酸残基48的不同构象过程之间存在平衡。去质子化后，天冬氨酸残基14或组氨酸残基48与酪氨酸25的侧链之间似乎形成了氢键，这是由归属于酪氨酸25的酪氨酸Cζ共振行为所表明的。加入抑制剂Cyd - 2'-P后，一个苯丙氨酸共振变宽并向高场移动，因此归属于苯丙氨酸120。该共振行为表明高场位移是由胞苷环的各向异性引起的。三个信号归属于三个苯丙氨酸残基。
