Enthalpies of hydrolysis of glutamine and asparagine and of ionization of glutamic and aspartic acids

Abstract

BIVALENT METAL COMPLEXES OF ATP AND ADP 395 4. The results also indicate the formation of a ternary complex between magnesium, adenosine triphosphate and 8-hydroxyquinoline.

A thermodynamic study of the hydrolysis of L-glutamine to (L-glutamate + ammonia) and of L-asparagine to (L -aspartate + ammonia)

“…Examination of the calorimetric results shows that the value of r H o m for reaction (5) obtained from the study of Kitzinger and Hems (21) differs from the result of the present study by 4.2 kJ · mol −1 . Also, the value of r H o m for reaction (6) obtained by them (21) is in dis-agreement by 5.6 kJ · mol −1 .…”

“…Also, the value of r H o m for reaction (6) obtained by them (21) is in dis-agreement by 5.6 kJ · mol −1 . In both cases, the results of the earlier studies are less exothermic than the results of the present study.…”

Thermodynamics of the first and second proton dissociations from aqueous l-aspartic acid and l-glutamic acid at temperatures from (278.15 to 393.15)K and at the pressure 0.35MPa: Apparent molar heat capacities and apparent molar volumes of zwitterionic, protonated cationic, and deprotonated anionic forms at molalities from (0.002 to 1.0)mol·kg−1

“…We found no results in the literature for D r C p,m for reaction (5) or (6) for either amino acid. Figure 8 shows D r H m (T, m) for reactions (5) and (6) together with values from the literature [19,[31][32][33][34][35][36][40][41][42][43][52][53][54]. The differences between our values of D r H m (T, m) for reaction (5) and those from the literature The ± values are from propagation of uncertainties as described in reference [60].…”

“…Reference values used for integration constants in this report for L-aspartic acid at T * = 298.15 are pK a = (1.95 3 ± 0.09 1 ) [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and [31][32][33][34][35][36] for reaction (5), and pK a = (3.7 6 ± 0.1 0 ) [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][37][38][39][40] and D r H m ¼ ð4:8 5 AE 0:9 0 Þ kJ Á mol À1 [32][33][34][35]41] for reaction (6). Reference values used for L-glutamic acid at T * = 298.15 are pK a = (2.19 5 ± 0.08 9 ) [25][26]…”

Thermodynamics of Enzymatic Reactions

“…Consider in greater detail the two reactions in which the amide bonds of asparagine and glutamine are hydrolyzed [65][66][67][68]71]: "0 NHj I = -02C-CH-CH2-CHz-COz +NHt (9) (L-glutamate) LlH r = -21.8 kJ mol-i ; LlG r = -11.7 kJ mol-i. Glycine-lysine -8.8±O.3 [67] As expected, the structurally similar compounds aspargine and glutamine have similar thermodynamic parameters for the hydrolysis reactions.…”