Bovine Serum Albumin-Catalyzed Deprotonation of [1-13C]Glycolaldehyde: Protein Reactivity toward Deprotonation of the α-Hydroxy α-Carbonyl Carbon
Bovine Serum Albumin-Catalyzed Deprotonation of [1-13C]Glycolaldehyde: Protein Reactivity toward Deprotonation of the α-Hydroxy α-Carbonyl Carbon
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DOI：
10.1021/bi101118g
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发表时间：
2010-09-07
期刊：
影响因子：
2.9
通讯作者：
Richard, John P.
中科院分区：
文献类型：
--
作者：
Go, Maybelle K.;Malabanan, M. Merced;Richard, John P.
在25℃和Pd 7.0的D2O中，牛血清白蛋白(BSA)催化[1-C-13]乙醇醛([1-C-13]GA)生成[1-C-13，2-H-2]GA和[1-C-13，2，2-di-H-2]GA。在反应初期，可以观察到[1-C-13，2-H-2]GA和[1-C-13，2，2-di-H-2]GA的生成，总收率为51+/-3%，随后在BSA的催化下，[1-C-13，2-H-2]GA被转化为[1-C-13，2，2-di-H-2]GA。这些氢交换反应的总二级速率常数[(k(E))(P)]等于0.25M-1 S(-1)。通过比较，0.04M-1 S(-1)[GO，M.K.，Amyes，T.L.和Richard，J.P.(2009)生化48,5769-5778]和0.06M-1 S(-1)[GO，M.K.，Koudelka，A.，Amyes，T.L.和Richard，J.P.(2010)生化49，分别对野生型和K12G突变体TIM催化的[1-C-13]GA的氢交换反应生成[1-C-13，2，2-di-H-2]GA进行了研究。这些数据表明，TIM和BSA对α-羟基α-羰基碳的去质子化有一定的催化活性。我们认为，这种活性是许多球状蛋白质固有的，必须提高这种活性，以证明有意义的从头设计的蛋白质催化剂的质子转移在α-羰基碳。
Bovine serum albumin (BSA) in D2O at 25 degrees C and pD 7.0 was found to catalyze the deuterium exchange reactions of [1-C-13]glycolaldehyde ([1-C-13]GA) to form [1-C-13,2-H-2]GA and [1-C-13,2,2-di-H-2]GA. The formation of [1-C-13,2-H-2]GA and [1-C-13,2,2-di-H-2]GA in a total yield of 51 +/- 3% was observed at early reaction times, and at later times, [1-C-13,2-H-2]GA was found to undergo BSA-catalyzed conversion to [1-C-13,2,2-di-H-2]GA. The overall second-order rate constant for these deuterium exchange reactions [(k(E))(p)] equals 0.25 M-1 s(-1). By comparison, (k(E))(p) values of 0.04 M-1 s(-1) [Go, M. K., Amyes, T. L., and Richard, J. P. (2009) Biochemistry 48, 5769-5778] and 0.06 M-1 s(-1) [Go, M. K., Koudelka, A., Amyes, T. L., and Richard, J. P. (2010) Biochemistry 49, 5377-5389] have been determined for the wild-type- and K 12G mutant TIM-catalyzed deuterium exchange reactions of[1-C-13]GA, respectively, to form [1-C-13,2,2-di-H-2]GA. These data show that TIM and BSA exhibit a modest catalytic activity toward deprotonation of the alpha-hydroxy alpha-carbonyl carbon. We suggest that this activity is intrinsic to many globular proteins, and that it must be enhanced to demonstrate meaningful de novo design of protein catalysts of proton transfer at alpha-carbonyl carbon.