Interaction of Sodium Dodecyl Sulfate with Multi-subunit Proteins: A case study with CARMIN

Sudhindra Rao, K. and Prakash, V. (1993) Interaction of Sodium Dodecyl Sulfate with Multi-subunit Proteins: A case study with CARMIN. Journal of Biological Chemistry, 268 (20). pp. 14769-14775.

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Abstract

Sodium dodecyl sulfate (SDS) dissociates the multi- meric protein, carmin, into its monomers (2 S ) at low concentration. Dissociation begins at and above 1.6 mM SDS concentration and reaches 50% at 5 mM SDS concentration. Denaturation occurs above 5 mM SDS concentration. The dissociation step involves binding of 640 f 50 mol of SDS/mol of protein with an associ- ation constant, K, of 6.90 f 0.35 X 10’ M-‘. The inter- action reflects a AG“ = -4.0 f 0.1 kcal mol”. In the denaturation step, the K, has the same value, and the y value is nearly 2-fold higher. Dissociation of carmin thus begins only above a binding of 0.60 g of SDS/g of protein. Analysis of the binding data at 37 “C indicates a maximum of 1030 f 90 mol of SDS bound/mol of protein, which is equivalent to 1.14 f 0.10 g of SDS/g of protein. Upon denaturation, the a-helix content of the protein increases from 4 to 15%. Kinetically, the denaturation process consists of a two-step process (a fast and a slow step). The first order rate constants for these steps are 89.6 2 8.1 and 16.8 f 1.5 min-’, re- spectively, at 6.3 mM SDS concentration. The proc- esses of dissociation and denaturation occur sequen- tially. Dissociation of the protein is reversible, whereas the process of denaturation is only partially reversible as reflected by sedimentation velocity and conforma- tional analysis. These data are taken as a model for general understanding of the dissociation and/or de- naturation processes, which could be either sequential or simultaneous in multimeric proteins.

Item Type:	Article
Uncontrolled Keywords:	Sodium dodecyl sulfate carmin multimeric protein anionic detergent
Subjects:	600 Technology > 08 Food technology > 16 Nutritive value > 03 Proteins
Divisions:	Protein Chemistry and Technology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	09 Jan 2008 05:53
Last Modified:	28 Dec 2011 09:32
URI:	http://ir.cftri.res.in/id/eprint/1618

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