Biswas A, Das K P
Protein Chemistry Laboratory, Department of Chemistry, Bose Institute, 93/1 A.P.C. Road, Kolkata 700 009, India.
Protein J. 2007 Jun;26(4):247-55. doi: 10.1007/s10930-006-9066-8.
alpha-Crystallin is known to act as a molecular chaperone by preventing the aggregation of partially unfolded substrate proteins. It is also known to assist the refolding of a number of denatured enzymes, but the activity yield is often less than 20%. In this paper, we have tried to tune the refolding ability of alpha-crystallin in vitro by optimizing various external parameters. We wanted to find out the best possible condition under which it can exhibit maximum refolding capacity. We found that under suitable condition in vitro alpha-crystallin can refold denatured malate dehydrogenase, carbonic anhydrase and lactate dehydrogenase to recover more than 40% activity. We also measured the effect of several external factors such as nucleotides, osmolytes, electrolytes, temperature etc. on the in vitro alpha-crystallin mediated reactivation of above stated enzymes. We found that nucleotides and electrolytes had little effect on the refolding ability of alpha-crystallin. However, in presence of different osmolytes, we found that its ability to reactivate denatured substrate proteins enhanced significantly. Refolding in presence of pre-incubated alpha-crystallin reveals that hydrophobicity had stronger influence on the refolding capacity of alpha-crystallin than its oligomeric size.
已知α-晶状体蛋白可作为分子伴侣，防止部分未折叠的底物蛋白聚集。它还能协助多种变性酶的重折叠，但活性产率通常低于20%。在本文中，我们试图通过优化各种外部参数来体外调节α-晶状体蛋白的重折叠能力。我们想找出它能展现最大重折叠能力的最佳条件。我们发现，在合适的体外条件下，α-晶状体蛋白可以使变性的苹果酸脱氢酶、碳酸酐酶和乳酸脱氢酶重折叠，以恢复超过40%的活性。我们还测定了几种外部因素，如核苷酸、渗透剂、电解质、温度等对体外α-晶状体蛋白介导的上述酶再活化的影响。我们发现核苷酸和电解质对α-晶状体蛋白的重折叠能力影响很小。然而，在不同渗透剂存在的情况下，我们发现它再活化变性底物蛋白的能力显著增强。在预孵育的α-晶状体蛋白存在下进行重折叠表明，疏水性对α-晶状体蛋白重折叠能力的影响比其寡聚体大小更强。
