Laser-induced photoacoustic calorimetric determination of enthalpy and volume changes in photolysis of 5′-deoxyadenosylcobalamin and methylcobalamin

Photolysis of 5′-deoxy-5′-adenosylcobalamin (AdoCbl) in neutral aqueous solution and methylcobalamin (MeCbl) in neutral and acid aqueous solution has been investigated using pulsed, time-resolved photoacoustic calorimetry in the temperature range 10–30 °C. The enthalpy changes for the above cobalamins, 129 ± 17, 163 ± 21 and 176 ± 23 kJ mol–1, respectively, are consistent with the values obtained by thermolytic kinetic methods. The reaction volume changes for them, 6 ± 1, 2 ± 0.5 and 5 ± 1 ml mol–1, respectively, are probably due to the conformational changes of the corrin ring and its side chains accompanying Co–C bond cleavage.

[1]  K. Brown,et al.  Thermolysis of Neopentylcobalamin Analogs Complexed to Haptocorrin: Side Chain Entropy and Activation of Organocobalamins for Carbon-Cobalt Bond Homolysis. , 1996, Inorganic Chemistry.

[2]  Silvia E. Braslavsky,et al.  TIME-RESOLVED VOLUME CHANGES DURING THE BACTERIORHODOPSIN PHOTOCYCLE : A PHOTOTHERMAL BEAM DEFLECTION STUDY , 1995 .

[3]  H. Marques,et al.  Side Chain Entropy and the Activation of Organocobalamins for Carbon-Cobalt Bond Homolysis: Thermolysis of Neopentylcobalamin-c-monocarboxylate, -c-N-methylamide, -c-N,N-dimethylamide, and -c-N-isopropylamide , 1995 .

[4]  K. Hellingwerf,et al.  Photoinduced volume change and energy storage associated with the early transformations of the photoactive yellow protein from Ectothiorhodospira halophila. , 1995, Biophysical journal.

[5]  Jean-Louis Habib Jiwan,et al.  Volume changes associated with intramolecular electron transfer during MLCT state formation. Time‐resolved optoacoustic studies of ruthenium cyano complexes , 1995 .

[6]  R. Matthews,et al.  How a protein binds B12: A 3.0 A X-ray structure of B12-binding domains of methionine synthase. , 1994, Science.

[7]  K. Brown,et al.  Toward an Understanding of the Activation of Organocobalt Corrinoids for Co-C Bond Homolysis in Aqueous Solution: Temperature Control in the Determination of Kinetic Constants for the Thermal Decomposition of Neopentylcobalamin , 1994 .

[8]  X. Zou,et al.  Side Chain Entropy and Activation of Organocobalamins for Thermal Homolysis: Thermolysis of Neopentyl-13-epi- and Neopentyl-8-epicobalamin in Neutral Aqueous Solution , 1994 .

[9]  S. Braslavsky,et al.  Combination of laser-induced optoacoustic spectroscopy (LIOAS) and semiempirical calculations for the determination of molecular volume changes : the photoisomerization of carbocyanines , 1994 .

[10]  A. Calafat,et al.  Investigations of B12 derivatives with inorganic ligands using 2D NMR spectroscopy. Ligand responsive shifts suggest that the deoxyadenosyl moiety in coenzyme B12 has a steric trans influence , 1993 .

[11]  K. Peters,et al.  A photoacoustic calorimetry study of horse carboxymyoglobin on the 10-nanosecond time scale. , 1993, Biophysical journal.

[12]  R. Finke,et al.  Neopentylcobalamin (NeopentylB12) cobalt-carbon bond thermolysis products, kinetics, activation parameters, and bond dissociation energy : a chemical model exhibiting 106 of the 1012 enzymic activation of coenzyme B12's cobalt-carbon bond , 1993 .

[13]  M. Chance,et al.  Continuous-wave quantum yields of various cobalamins are influenced by competition between geminate recombination and cage escape. , 1993, Biochemistry.

[14]  J. M. Pratt.  Nature’s design and use of catalysts based on Co and the macrocyclic corrin ligand: 4 x 109 years of coordination chemistry , 1993 .

[15]  S. Braslavsky,et al.  Time-resolved photothermal and photoacoustic methods applied to photoinduced processes in solution , 1992 .

[16]  T. Logan,et al.  Photoacoustic calorimetry study of human carboxyhemoglobin , 1992 .

[17]  J. J. Grabowski,et al.  Enthalpy measurements in organic solvents by photoacoustic calorimetry : a solution to the reaction volume problem , 1992 .

[18]  K. Brown,et al.  Effects of axial ligation on the thermolysis of benzyl- and neopentylcobamides: analysis of the base-on effect , 1991 .

[19]  L. Marzilli,et al.  Rare .alpha.-alkyl isomers of cobalamins: synthesis, characterization, and properties of two diastereomers of the .alpha.-alkylcobalamin, .alpha.-(2-oxo-1,3-dioxolan-4-yl)cobalamin , 1991 .

[20]  K. Brown,et al.  Stabilization of thermally labile alkylcobalamins by a haptocorrin from chicken serum. , 1991, Journal of Biological Chemistry.

[21]  H. L. Carrell,et al.  X-ray crystallographic and two-dimensional NMR investigations of a coenzyme B12 analogue with 5'-deoxyadenosine replaced by 9-(CH2)3-adenine , 1991 .

[22]  S. Sligar,et al.  Role of the arginine-45 salt bridge in ligand dissociation from sperm whale carboxymyoglobin as probed by photoacoustic calorimetry. , 1990, Biochemistry.

[23]  R. Finke,et al.  Cobalt-carbon homolysis and bond dissociation energy studies of biological alkylcobalamins: methylcobalamin, including a.gtoreq.1015 Co-CH3 homolysis rate enhancement at 25.degree. following one-electron reduction , 1990 .

[24]  J. Goodman,et al.  Reaction volumes of excited state photoprocesses , 1989 .

[25]  J. Goodman,et al.  Determination of the enthalpy and reaction volume changes of organic photoreactions using photoacoustic calorimetry , 1989 .

[26]  L. Marzilli,et al.  Solution behavior and complete proton and carbon-13 NMR assignments of the coenzyme B12 derivative (5'-deoxyadenosyl)cobinamide using modern 2D NMR experiments, including 600 MHz proton NMR data , 1989 .

[27]  T. Toraya,et al.  Acceleration of cleavage of the carbon-cobalt bond of sterically hindered alkylcobalamins by binding to apoprotein of diol dehydrase. , 1988, Biochemistry.

[28]  K. Peters,et al.  Time-resolved photoacoustic calorimetry: probing the energetics and dynamics of fast chemical and biochemical reactions. , 1988, Science.

[29]  J. Halpern,et al.  Thermal decomposition and cobalt-carbon bond dissociation energies of organocobalamins: neopentyl-, (cyclopentylmethyl)-, (cyclohexylmethyl)-, (tetrahydrofurfuryl)- and ((tetrahydro-2H-pyryl)methyl)cobalamin , 1988 .

[30]  J. Westrick,et al.  A time-resolved photoacoustic calorimetry study of the dynamics of enthalpy and volume changes produced in the photodissociation of carbon monoxide from sperm whale carboxymyoglobin. , 1987, Biochemistry.

[31]  B. Hay,et al.  Thermolysis of the cobalt-carbon bond in adenosylcorrins. 3. Quantification of the axial base effect in adenosylcobalamin by the synthesis and thermolysis of axial base-free adenosylcobinamide. Insights into the energetics of enzyme-assisted cobalt-carbon bond homolysis , 1987 .

[32]  Peter Murray-Rust,et al.  Conformational variability of corrins: some methods of analysis , 1987 .

[33]  J. Halpern,et al.  Why does nature not use the porphyrin ligand in vitamin B12 , 1987 .

[34]  A. Bax,et al.  New insights into the solution behavior of cobalamins. Studies of the base-off form of coenzyme B12 using modern two-dimensional NMR methods , 1987 .

[35]  B. Hay,et al.  Thermolysis of the cobalt-carbon bond of adenosylcobalamin. 2. Products, kinetics, and cobalt-carbon bond dissociation energy in aqueous solution , 1986 .

[36]  A. Bax,et al.  Complete proton and carbon-13 assignments of coenzyme B12 through the use of new two-dimensional NMR experiments , 1986 .

[37]  J. Espenson,et al.  Homolysis and electron-transfer reactions of benzylcobalamin , 1985 .

[38]  W. Lipscomb,et al.  A molecular orbital evaluation of possible factors affecting the homolytic activation of coenzyme B12 , 1985 .

[39]  M. Summers,et al.  The structure of a B12 coenzyme: methylcobalamin studies by x-ray and NMR methods , 1985 .

[40]  J. Halpern.  Mechanisms of coenzyme B12-dependent rearrangements. , 1985, Science.

[41]  J. Halpern,et al.  Cobalt-carbon bond dissociation energy of coenzyme B12 , 1984 .

[42]  B. Hay,et al.  Thermolysis of adenosylcobalamin: a product, kinetic, and Co-C5' bond dissociation energy study , 1984 .

[43]  J. Halpern.  Mechanistic aspects of coenzyme B12-dependent rearrangements. Organometallics as free radical precursors , 1983 .

[44]  J. Halpern,et al.  Kinetic determination of transition metal-alkyl bond dissociation energies: application to organocobalt compounds related to B12 coenzymes , 1982 .

[45]  T. Netzel,et al.  Early events and transient chemistry in the photohomolysis of alkylcobalamins , 1979 .

[46]  R. Taylor,et al.  Aerobic photolysis of alkylcobalamins: quantum yields and light-action spectra. , 1973, Archives of biochemistry and biophysics.

[47]  D. Hodgkin,et al.  Structure of the 5,6-Dimethylbenzimidazolylcobamide Coenzyme , 1961, Nature.