CALORIMETRIC HEAT OF HELIX-COIL TRANSITION OF POLY-L-GLUTAMIC ACID
CALORIMETRIC HEAT OF HELIX-COIL TRANSITION OF POLY-L-GLUTAMIC ACID
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DOI：
10.1021/ja00976a007
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发表时间：
1966-01-01
影响因子：
15
通讯作者：
HERMANS, J
中科院分区：
文献类型：
--
作者：
RIALDI, G;HERMANS, J
当多聚L谷氨酸钠溶液酸化时，聚合物经历了从无规卷曲到螺旋的转变。用卡尔维微量热计测量了与这些pH变化相关的热变。在由旋光度的变化检测到转变的范围内，热焓发生突变，但与pH无关。测得其构象变化热值为-1100卡/摩尔单体单位，与先前由不同温度下的电位滴定曲线测得的值一致。这种大的负值被认为是由于多肽氢键的负值可能更大所致。
When solutions of sodium poly-L-glutamate are acidified, the polymer undergoes a transition from random coil to helix. The changes in enthalpy associated with these pH changes have been measured using a Calvet microcalorimeter. The enthalpy was found to change abruptly in therange where the transition is detected from a change in optical rotation but is otherwise independent of pH. The enthalpy of the conformational change is determined to be— 1100 cal/mole of monomer unit, and is found to be in agreement with the value obtained earlier from potentiometric titration curves at various temperatures. This large negative value is considered to be due to a perhaps even larger negative heat of formation of the peptidehydrogen bond.