肌红蛋白热变性中二级结构变化的临界温度高达 130°C 以及十二烷基硫酸钠对该变化的影响。

Critical temperature of secondary structural change of myoglobin in thermal denaturation up to 130 degrees C and effect of sodium dodecyl sulfate on the change.

机构信息

Department of Applied Chemistry and Biotechnology, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan.

出版信息

J Phys Chem B. 2010 Feb 25;114(7):2430-4. doi: 10.1021/jp908700j.

DOI:10.1021/jp908700j

PMID:20112986

Abstract

The secondary structural change of horse heart myoglobin was examined in the thermal denaturation up to 130 degrees C. The original helicity of 82% gradually decreased to 67% with rise of temperature until 75 degrees C. Thereafter, it suddenly decreased to 24% at 90 degrees C and then slightly decreased to 14% at 130 degrees C. The helices of this protein were mostly destroyed between 75 and 100 degrees C. On the other hand, upon cooling to 25 degrees C from temperatures below 75 degrees C, the helicity completely recovered to the original value, but it did not after heating to temperatures above 80 degrees C. Thus, myoglobin maintains the reversibility of the structural change up to a temperature as high as 75 degrees C. This protein had another critical temperature around 90-100 degrees C in addition to 75 degrees C in the present thermal denaturation. Upon cooling to 25 degrees C after heating to temperatures above 80 degrees C, the extent of recovered helicity decreased with rise of temperature before cooling. The additive effect of sodium dodecyl sulfate (SDS) on the structural change of myoglobin differed below and above the critical temperature at 75 degrees C. In the temperature range below 75 degrees C where the structural change was reversible, the presence of SDS cooperated with the thermal denaturation to disrupt the structure. On the contrary, the presence of the surfactant more or less restrained the decrement of helicity at high temperatures above 85 degrees C. The helicity decreased and increased with an increase of SDS concentration upon cooling to 25 degrees C after heating to temperatures below 75 degrees C and after heating to temperatures above 85 degrees C, respectively. Then, upon cooling to 25 degrees C from any temperature, the helicity settled to a magnitude around 60% in the presence of the surfactant above 0.6 mM.

摘要

研究了马心肌球蛋白在热变性过程中的二级结构变化，温度高达 130°C。随着温度的升高，其原始螺旋度从 82%逐渐降至 75°C 时的 67%，此后在 90°C 时突然降至 24%，然后在 130°C 时略有下降至 14%。该蛋白质的螺旋结构在 75-100°C 之间大部分被破坏。另一方面，当温度从 75°C 以下冷却到 25°C 时，螺旋度完全恢复到原始值，但在加热到 80°C 以上的温度后则不会。因此，肌红蛋白在高达 75°C 的温度下保持结构变化的可逆性。除了 75°C 时的热变性外，该蛋白质在 90-100°C 左右还有另一个临界温度。当加热到 80°C 以上的温度后再冷却到 25°C 时，随着冷却前温度的升高，恢复的螺旋度逐渐减小。十二烷基硫酸钠（SDS）对肌红蛋白结构变化的影响在 75°C 以下和以上的临界温度时不同。在结构变化可逆的 75°C 以下温度范围内，SDS 的存在与热变性协同作用破坏结构。相反，在 85°C 以上的高温下，表面活性剂的存在或多或少地抑制了螺旋度的下降。在加热到 75°C 以下和加热到 85°C 以上的温度后冷却到 25°C 时，SDS 浓度的增加导致螺旋度降低和增加，然后在任何温度下冷却到 25°C 时，在表面活性剂存在下，螺旋度稳定在 60%左右，表面活性剂浓度高于 0.6mM。