Chemical approaches to penicillin allergy - IV. Binding of carrier receptor protein with penicillin and its analogues

Mandal, Chitra ; Mandal, Chabbinath ; Bhattacharyya, P. K. (1978) Chemical approaches to penicillin allergy - IV. Binding of carrier receptor protein with penicillin and its analogues Proceedings of the Indian Academy of Sciences - Chemical Sciences, 87 (6). pp. 145-163. ISSN 0253-4134

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The availability of electrophoretically homogeneous rabbit penicillin carrier receptor protein (CRP) by affinity chromatography afforded an idealin vitro system to calculate the thermodynamic parameters of binding of penicillin and analogues with CRP as well as competitive binding of such analogues with CRP in presence of14C-penicillin G. The kinetics of association of CRP with 7-deoxy penicillin which does not bind covalently with CRP have been studied through equilibrium dialysis with14C-7-deoxybenzyl penicillin and found to be K=2.79x106M-1.-ΔG=8.106 k cal/mole as well as fluorescence quenching studies with exciter λ280 K=3.573x106M-1,-ΔG=8.239 k cal/mole. The fluorescence quenching studies have been extended to CRP-benzyl penicillin and CRP-6-aminopenicillanic acid (6APA) systems also. The fluorescence data with benzyl penicillin indicate two conformational changes in CRP-a fast change corresponding to the non-covalent binding to CRP with 7-deoxy penicillin and a slower change due to covalent bond formation. With 6-APA the first change is not observed but the conformational change corresponding to covalent binding is only seen. Competitive binding studies indicate that the order of binding of CRP with the analogues of penicillin is as follows: methicillin > 6APA > carbenicillin >o-nitrobenzyl penicillin > cloxacillin ≈ benzyl penicillin ≈ 6-phenyl acetamido penicillanyl alcohol ≈ 7 phenyl acetamido desacetoxy cephalosporanic acid ≈ p-amino benzyl penicillin ≈ p-nitro benzyl penicillin > ticarcillin >o-amino benzyl penicillin > amoxycillin > 7-deoxy benzyl penicillin > ampicillin. From these data it has been possible to delineate partially the topology of the penicillin binding cleft of the CRP as well as some of the functional groups in the cleft responsible for the binding process.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Penicillin Allergy; Hapten Binding Sites; Antigen-antibody Reaction; Conformation; Affinity Chromatography; Kinetic Study and Fluorescence Quenching
ID Code:87035
Deposited On:14 Mar 2012 13:56
Last Modified:19 May 2016 02:26

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