青霉素G和氨苄青霉素水解的热力学

Thermodynamics of the hydrolysis of penicillin G and ampicillin.

作者信息

Kishore N, Tewari Y B, Yap W T, Goldberg R N

机构信息

Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899.

出版信息

Biophys Chem. 1994 Mar;49(2):163-74. doi: 10.1016/0301-4622(93)e0067-f.

DOI:10.1016/0301-4622(93)e0067-f

PMID:8155816

Abstract

Apparent equilibrium constants and calorimetric enthalpies of reaction have been measured for the beta-lactamase catalyzed hydrolysis of penicillin G(aq) and ampicillin(aq) to penicillinoic acid(aq) and to ampicillinoic acid(aq), respectively. High-pressure liquid-chromatography and microcalorimetry were used to perform these measurements. The results for the reference reactions at T = 298.15 K and Im = 0 are: Ko = (9.4 +/- 3.1) x 10(-7), delta rGo = (34.4 +/- 1.0)kJ mol-1, delta rHo = -(73.7 +/- 0.4)kJ mol-1, and delta rSo = -(363 +/- 4) J K-1 mol-1 for penicillin G-(aq) + H2O(1) = penicillinoic acid2-(aq) + H+(aq); Ko = (6.0 +/- 3.0) x 10(-6), delta rGo = (29.8 +/- 1.7) kJ mol-1, delta rHo = -(70.0 +/- 7.5) kJ mol-1, and delta rSo = -(335 +/- 26) J K-1 mol-1 for ampicillin-(aq)+ H2O(1) = ampicillinoic acid2-(aq)+H+(aq). Calorimetric enthalpies of reaction for the beta-lactamase catalyzed hydrolysis of cephalosporin C have also been measured but the reaction products have not been identified and the measured enthalpies cannot be assigned to a specific reaction. Acidity constants for ampicillin, penicillin G, ampicillinoic acid, and penicillinoic acid are also reported. A strain energy of 116 kJ mol-1 for the beta-lactam ring is obtained from thermochemical data.

摘要

已分别测定了β-内酰胺酶催化青霉素G（水溶液）和氨苄青霉素（水溶液）水解生成青霉噻唑酸（水溶液）和氨苄青霉噻唑酸（水溶液）的表观平衡常数和反应的量热焓。采用高压液相色谱法和微量量热法进行这些测量。在T = 298.15 K和Im = 0时，参考反应的结果如下：对于青霉素G-（水溶液）+ H₂O（l）=青霉噻唑酸²-（水溶液）+ H⁺（水溶液），Ko =（9.4±3.1）×10⁻⁷，ΔrGo =（34.4±1.0）kJ mol⁻¹，ΔrHo = -（73.7±0.4）kJ mol⁻¹，ΔrSo = -（363±4）J K⁻¹ mol⁻¹；对于氨苄青霉素-（水溶液）+ H₂O（l）=氨苄青霉噻唑酸²-（水溶液）+ H⁺（水溶液），Ko =（6.0±3.0）×10⁻⁶，ΔrGo =（29.8±1.7）kJ mol⁻¹，ΔrHo = -（70.0±7.5）kJ mol⁻¹，ΔrSo = -（335±26）J K⁻¹ mol⁻¹。还测定了β-内酰胺酶催化头孢菌素C水解的反应量热焓，但反应产物尚未鉴定，所测焓值无法指定给特定反应。还报道了氨苄青霉素、青霉素G、氨苄青霉噻唑酸和青霉噻唑酸的酸度常数。根据热化学数据得出β-内酰胺环的应变能为116 kJ mol⁻¹。