Initial step of B12-dependent enzymatic catalysis: energetic implications regarding involvement of the one-electron-reduced form of adenosylcobalamin cofactor
Tóm tắt
Density functional theory analysis was performed to elucidate the impact of one-electron reduction upon the initial step of adenosylcobalamin-dependent enzymatic catalysis. The transition state (TS) corresponding to the Co–C bond cleavage and subsequent hydrogen abstraction from the substrate was located. The intrinsic reaction coordinate calculations predicted that the reaction consisting of Co–C5′ bond cleavage in [CoIII(corrin•)]–Rib (where Rib is ribosyl) and hydrogen-atom abstraction from the CH3–CH2–CHO substrate occurs in a concerted fashion. The computed activation energy barrier of the reaction (15.0 kcal/mol) was lowered by approximately 54.5% in comparison with the reaction involving the positively charged cofactor model (Im–[CoIII(corrin)]–Rib+, where Im is imidazole; energy barrier = 33.0 kcal/mol). The Im base was detached during the TS search in the reaction involving the one-electron-reduced analogue. Thus, to compare the energetics of the two reactions, the axial Im ligand detachment energy for the Im–[CoIII(corrin•)]–Rib model was computed [7.6 kcal/mol (gas phase); 4.6 kcal/mol (water)]. Consequently, the effective activation energy barrier for the reaction mediated by the Im-off [CoIII(corrin•)]–Rib was estimated to be 22.6 kcal/mol, which implied an overall 31.5% reduction in the energetic demands of the reaction. Considering that the lengthened Co–Naxial bond has been observed in X-ray crystal structure studies of B12-dependent mutases, the catalytic impact induced by one-electron reduction of the cofactor is expected to be higher in the presence of the enzymatic environment.
Tài liệu tham khảo
Marzilli LG (1993) In: Reedijk J (ed) Bioinorganic catalysis. Marcel Dekker, New York, p 227
Kräutler B, Arigoni D, Golding BT (eds) (1998) Vitamin B12 and B12 proteins. Lectures presented at the 4th European symposium on vitamin B12 and B12 proteins. Wiley-VCH, New York
Banerjee R (1999) Chemistry and biochemistry of B12. Wiley, New York
Toraya T (2003) Chem Rev 103:2095–2127
Toraya T (2000) Cell Mol Life Sci 57:106–127
Banerjee R (2003) Chem Rev 103:2083–2094
Brown KL (2005) Chem Rev 105:2075–2149
Randaccio L, Geremia S, Nardin G, Wuerges J (2006) J Coord Chem Rev 250:1332–1350
Randaccio L, Geremia S, Wuerges J (2007) J Organomet Chem 692:1198
Halpern J (1985) Science 227:869–875
Finke RG (1998) In: Kräutler B, Arigoni D, Golding BT (eds) Vitamin B12 and B12 proteins, chap 25. Wiley-VCH, Weinheim
Chowdhury S, Banerjee R (2000) Biochemistry 39:7998–8006
Kumar M, Kozlowski PM (2009) J Phys Chem B 113:9050–9054
Kozlowski PM, Kamachi T, Kumar M, Nakayama T, Yoshizawa K (2010) J Phys Chem B 114:5928–5937
Lexa D, Savéant J-M (1983) Acc Chem Res 16:235–243
Birke RL, Huang Q, Spataru T, Gosser DK Jr (2006) J Am Chem Soc 128:1922–1936
Vass I, Styring S (1991) Biochemistry 30:830–839
Miller A-F (2008) Acc Chem Res 41:501–510
Blomberg MRA, Siegbahn PEM, Babcock GT (1998) J Am Chem Soc 120:8812–8824
Becke AD (1986) J Chem Phys 84:4524–4529
Perdew JP (1986) Phys Rev B 33:8822–8824
Jensen KP, Ryde U (2003) J Phys Chem A 107:7539–7545
Kuta J, Patchkovskii S, Zgierski MZ, Kozlowski PM (2006) J Comput Chem 27:1429–1437
Kozlowski PM, Kamachi T, Toraya T, Yoshizawa K (2007) Angew Chem Int Ed 46:980–983
Finke RG, Hay BP (1984) Inorg Chem 23:3041–3043
Hay BP, Finke RG (1986) J Am Chem Soc 108:4820–4829
Finke RG, Hay BP (1988) Polyhedron 7:1469–1481
Luo LB, Li G, Chen HL, Fu SW, Zhang SY (1998) J Chem Soc Dalton Trans 2103–2107
Kozlowski PM, Kuta J, Galezowski W (2007) J Phys Chem B 111:7638–7645
Galezowski W, Kuta J, Kozlowski PM (2008) J Phys Chem B 112:3177–3183
Brown KL, Peck-Siler S (1988) Inorg Chem 27:3548–3555
Sirovatka-Dorweiler J, Matthews RG, Finke RG (2002) Inorg Chem 41:6217–6224
Mancia F, Evans PR (1998) Structure 6:711–720
Gruber K, Reitzer R, Kratky C (2001) Angew Chem 113:3481–3484
Alfonso-Prieto M, Biarnés X, Kumar M, Rovira C, Kozlowski PM (2010) J Phys Chem B 114:12965–12971
Lexa D, Savéant J-M (1978) J Am Chem Soc 100:3220–3222
Kim M-H, Birke RL (1983) J Electroanal Chem 144:331–350
Spataru T, Birke RL (2006) J Electroanal Chem 593:74–86
Schosser SG, Hannak RB, Konrat R, Gruber K, Mikl C, Kratky C, Kräutler B (2005) Chem Eur J 11:81–93
Fukuoka M, Nakanishi Y, Hannak RB, Kräutler B, Toraya T (2005) FEBS J 272:4787–4796
Friendorf M, Kozlowski PM (2004) J Am Chem Soc 126:1928–1929
Buckel W, Golding BT, Kratky C (2006) Chem Eur J 272:352–362